staticcheck (#313)

* CI: use staticcheck for linting

This commit switches the linter for Go code from golint to staticcheck.
Golint has been deprecated since last year and staticcheck is a
recommended replacement.

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

* revendor

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

* cmd,pkg: fix lint warnings

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

vendor/honnef.co/go/tools/LICENSE

@@ -0,0 +1,20 @@
+Copyright (c) 2016 Dominik Honnef
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

vendor/honnef.co/go/tools/LICENSE-THIRD-PARTY

@@ -0,0 +1,121 @@
+Staticcheck and its related tools make use of third party projects,
+either by reusing their code, or by statically linking them into
+resulting binaries. These projects are:
+
+* The Go Programming Language - https://golang.org/
+  golang.org/x/mod - https://github.com/golang/mod
+  golang.org/x/tools - https://github.com/golang/tools
+  golang.org/x/sys - https://github.com/golang/sys
+  golang.org/x/xerrors - https://github.com/golang/xerrors
+
+    Copyright (c) 2009 The Go Authors. All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are
+    met:
+
+       * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+    copyright notice, this list of conditions and the following disclaimer
+    in the documentation and/or other materials provided with the
+    distribution.
+       * Neither the name of Google Inc. nor the names of its
+    contributors may be used to endorse or promote products derived from
+    this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+* github.com/BurntSushi/toml - https://github.com/BurntSushi/toml
+
+    The MIT License (MIT)
+
+    Copyright (c) 2013 TOML authors
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+* gogrep - https://github.com/mvdan/gogrep
+
+    Copyright (c) 2017, Daniel Martí. All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are
+    met:
+
+       * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+    copyright notice, this list of conditions and the following disclaimer
+    in the documentation and/or other materials provided with the
+    distribution.
+       * Neither the name of the copyright holder nor the names of its
+    contributors may be used to endorse or promote products derived from
+    this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+* gosmith - https://github.com/dvyukov/gosmith
+
+    Copyright (c) 2014 Dmitry Vyukov. All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are
+    met:
+
+       * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+    copyright notice, this list of conditions and the following disclaimer
+    in the documentation and/or other materials provided with the
+    distribution.
+       * The name of Dmitry Vyukov may be used to endorse or promote
+    products derived from this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/honnef.co/go/tools/analysis/code/code.go

@@ -0,0 +1,342 @@
+// Package code answers structural and type questions about Go code.
+package code
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"strings"
+
+	"honnef.co/go/tools/analysis/facts"
+	"honnef.co/go/tools/go/ast/astutil"
+	"honnef.co/go/tools/go/types/typeutil"
+	"honnef.co/go/tools/pattern"
+
+	"golang.org/x/exp/typeparams"
+	"golang.org/x/tools/go/analysis"
+)
+
+type Positioner interface {
+	Pos() token.Pos
+}
+
+func IsOfType(pass *analysis.Pass, expr ast.Expr, name string) bool {
+	return typeutil.IsType(pass.TypesInfo.TypeOf(expr), name)
+}
+
+func IsInTest(pass *analysis.Pass, node Positioner) bool {
+	// FIXME(dh): this doesn't work for global variables with
+	// initializers
+	f := pass.Fset.File(node.Pos())
+	return f != nil && strings.HasSuffix(f.Name(), "_test.go")
+}
+
+// IsMain reports whether the package being processed is a package
+// main.
+func IsMain(pass *analysis.Pass) bool {
+	return pass.Pkg.Name() == "main"
+}
+
+// IsMainLike reports whether the package being processed is a
+// main-like package. A main-like package is a package that is
+// package main, or that is intended to be used by a tool framework
+// such as cobra to implement a command.
+//
+// Note that this function errs on the side of false positives; it may
+// return true for packages that aren't main-like. IsMainLike is
+// intended for analyses that wish to suppress diagnostics for
+// main-like packages to avoid false positives.
+func IsMainLike(pass *analysis.Pass) bool {
+	if pass.Pkg.Name() == "main" {
+		return true
+	}
+	for _, imp := range pass.Pkg.Imports() {
+		if imp.Path() == "github.com/spf13/cobra" {
+			return true
+		}
+	}
+	return false
+}
+
+func SelectorName(pass *analysis.Pass, expr *ast.SelectorExpr) string {
+	info := pass.TypesInfo
+	sel := info.Selections[expr]
+	if sel == nil {
+		if x, ok := expr.X.(*ast.Ident); ok {
+			pkg, ok := info.ObjectOf(x).(*types.PkgName)
+			if !ok {
+				// This shouldn't happen
+				return fmt.Sprintf("%s.%s", x.Name, expr.Sel.Name)
+			}
+			return fmt.Sprintf("%s.%s", pkg.Imported().Path(), expr.Sel.Name)
+		}
+		panic(fmt.Sprintf("unsupported selector: %v", expr))
+	}
+	if v, ok := sel.Obj().(*types.Var); ok && v.IsField() {
+		return fmt.Sprintf("(%s).%s", typeutil.DereferenceR(sel.Recv()), sel.Obj().Name())
+	} else {
+		return fmt.Sprintf("(%s).%s", sel.Recv(), sel.Obj().Name())
+	}
+}
+
+func IsNil(pass *analysis.Pass, expr ast.Expr) bool {
+	return pass.TypesInfo.Types[expr].IsNil()
+}
+
+func BoolConst(pass *analysis.Pass, expr ast.Expr) bool {
+	val := pass.TypesInfo.ObjectOf(expr.(*ast.Ident)).(*types.Const).Val()
+	return constant.BoolVal(val)
+}
+
+func IsBoolConst(pass *analysis.Pass, expr ast.Expr) bool {
+	// We explicitly don't support typed bools because more often than
+	// not, custom bool types are used as binary enums and the
+	// explicit comparison is desired.
+
+	ident, ok := expr.(*ast.Ident)
+	if !ok {
+		return false
+	}
+	obj := pass.TypesInfo.ObjectOf(ident)
+	c, ok := obj.(*types.Const)
+	if !ok {
+		return false
+	}
+	basic, ok := c.Type().(*types.Basic)
+	if !ok {
+		return false
+	}
+	if basic.Kind() != types.UntypedBool && basic.Kind() != types.Bool {
+		return false
+	}
+	return true
+}
+
+func ExprToInt(pass *analysis.Pass, expr ast.Expr) (int64, bool) {
+	tv := pass.TypesInfo.Types[expr]
+	if tv.Value == nil {
+		return 0, false
+	}
+	if tv.Value.Kind() != constant.Int {
+		return 0, false
+	}
+	return constant.Int64Val(tv.Value)
+}
+
+func ExprToString(pass *analysis.Pass, expr ast.Expr) (string, bool) {
+	val := pass.TypesInfo.Types[expr].Value
+	if val == nil {
+		return "", false
+	}
+	if val.Kind() != constant.String {
+		return "", false
+	}
+	return constant.StringVal(val), true
+}
+
+func CallName(pass *analysis.Pass, call *ast.CallExpr) string {
+	fun := astutil.Unparen(call.Fun)
+
+	// Instantiating a function cannot return another generic function, so doing this once is enough
+	switch idx := fun.(type) {
+	case *ast.IndexExpr:
+		fun = idx.X
+	case *typeparams.IndexListExpr:
+		fun = idx.X
+	}
+
+	// (foo)[T] is not a valid instantiationg, so no need to unparen again.
+
+	switch fun := fun.(type) {
+	case *ast.SelectorExpr:
+		fn, ok := pass.TypesInfo.ObjectOf(fun.Sel).(*types.Func)
+		if !ok {
+			return ""
+		}
+		return typeutil.FuncName(fn)
+	case *ast.Ident:
+		obj := pass.TypesInfo.ObjectOf(fun)
+		switch obj := obj.(type) {
+		case *types.Func:
+			return typeutil.FuncName(obj)
+		case *types.Builtin:
+			return obj.Name()
+		default:
+			return ""
+		}
+	default:
+		return ""
+	}
+}
+
+func IsCallTo(pass *analysis.Pass, node ast.Node, name string) bool {
+	call, ok := node.(*ast.CallExpr)
+	if !ok {
+		return false
+	}
+	return CallName(pass, call) == name
+}
+
+func IsCallToAny(pass *analysis.Pass, node ast.Node, names ...string) bool {
+	call, ok := node.(*ast.CallExpr)
+	if !ok {
+		return false
+	}
+	q := CallName(pass, call)
+	for _, name := range names {
+		if q == name {
+			return true
+		}
+	}
+	return false
+}
+
+func File(pass *analysis.Pass, node Positioner) *ast.File {
+	m := pass.ResultOf[facts.TokenFile].(map[*token.File]*ast.File)
+	return m[pass.Fset.File(node.Pos())]
+}
+
+// IsGenerated reports whether pos is in a generated file, It ignores
+// //line directives.
+func IsGenerated(pass *analysis.Pass, pos token.Pos) bool {
+	_, ok := Generator(pass, pos)
+	return ok
+}
+
+// Generator returns the generator that generated the file containing
+// pos. It ignores //line directives.
+func Generator(pass *analysis.Pass, pos token.Pos) (facts.Generator, bool) {
+	file := pass.Fset.PositionFor(pos, false).Filename
+	m := pass.ResultOf[facts.Generated].(map[string]facts.Generator)
+	g, ok := m[file]
+	return g, ok
+}
+
+// MayHaveSideEffects reports whether expr may have side effects. If
+// the purity argument is nil, this function implements a purely
+// syntactic check, meaning that any function call may have side
+// effects, regardless of the called function's body. Otherwise,
+// purity will be consulted to determine the purity of function calls.
+func MayHaveSideEffects(pass *analysis.Pass, expr ast.Expr, purity facts.PurityResult) bool {
+	switch expr := expr.(type) {
+	case *ast.BadExpr:
+		return true
+	case *ast.Ellipsis:
+		return MayHaveSideEffects(pass, expr.Elt, purity)
+	case *ast.FuncLit:
+		// the literal itself cannot have side effects, only calling it
+		// might, which is handled by CallExpr.
+		return false
+	case *ast.ArrayType, *ast.StructType, *ast.FuncType, *ast.InterfaceType, *ast.MapType, *ast.ChanType:
+		// types cannot have side effects
+		return false
+	case *ast.BasicLit:
+		return false
+	case *ast.BinaryExpr:
+		return MayHaveSideEffects(pass, expr.X, purity) || MayHaveSideEffects(pass, expr.Y, purity)
+	case *ast.CallExpr:
+		if purity == nil {
+			return true
+		}
+		switch obj := typeutil.Callee(pass.TypesInfo, expr).(type) {
+		case *types.Func:
+			if _, ok := purity[obj]; !ok {
+				return true
+			}
+		case *types.Builtin:
+			switch obj.Name() {
+			case "len", "cap":
+			default:
+				return true
+			}
+		default:
+			return true
+		}
+		for _, arg := range expr.Args {
+			if MayHaveSideEffects(pass, arg, purity) {
+				return true
+			}
+		}
+		return false
+	case *ast.CompositeLit:
+		if MayHaveSideEffects(pass, expr.Type, purity) {
+			return true
+		}
+		for _, elt := range expr.Elts {
+			if MayHaveSideEffects(pass, elt, purity) {
+				return true
+			}
+		}
+		return false
+	case *ast.Ident:
+		return false
+	case *ast.IndexExpr:
+		return MayHaveSideEffects(pass, expr.X, purity) || MayHaveSideEffects(pass, expr.Index, purity)
+	case *typeparams.IndexListExpr:
+		// In theory, none of the checks are necessary, as IndexListExpr only involves types. But there is no harm in
+		// being safe.
+		if MayHaveSideEffects(pass, expr.X, purity) {
+			return true
+		}
+		for _, idx := range expr.Indices {
+			if MayHaveSideEffects(pass, idx, purity) {
+				return true
+			}
+		}
+		return false
+	case *ast.KeyValueExpr:
+		return MayHaveSideEffects(pass, expr.Key, purity) || MayHaveSideEffects(pass, expr.Value, purity)
+	case *ast.SelectorExpr:
+		return MayHaveSideEffects(pass, expr.X, purity)
+	case *ast.SliceExpr:
+		return MayHaveSideEffects(pass, expr.X, purity) ||
+			MayHaveSideEffects(pass, expr.Low, purity) ||
+			MayHaveSideEffects(pass, expr.High, purity) ||
+			MayHaveSideEffects(pass, expr.Max, purity)
+	case *ast.StarExpr:
+		return MayHaveSideEffects(pass, expr.X, purity)
+	case *ast.TypeAssertExpr:
+		return MayHaveSideEffects(pass, expr.X, purity)
+	case *ast.UnaryExpr:
+		if MayHaveSideEffects(pass, expr.X, purity) {
+			return true
+		}
+		return expr.Op == token.ARROW || expr.Op == token.AND
+	case *ast.ParenExpr:
+		return MayHaveSideEffects(pass, expr.X, purity)
+	case nil:
+		return false
+	default:
+		panic(fmt.Sprintf("internal error: unhandled type %T", expr))
+	}
+}
+
+func IsGoVersion(pass *analysis.Pass, minor int) bool {
+	f, ok := pass.Analyzer.Flags.Lookup("go").Value.(flag.Getter)
+	if !ok {
+		panic("requested Go version, but analyzer has no version flag")
+	}
+	version := f.Get().(int)
+	return version >= minor
+}
+
+var integerLiteralQ = pattern.MustParse(`(IntegerLiteral tv)`)
+
+func IntegerLiteral(pass *analysis.Pass, node ast.Node) (types.TypeAndValue, bool) {
+	m, ok := Match(pass, integerLiteralQ, node)
+	if !ok {
+		return types.TypeAndValue{}, false
+	}
+	return m.State["tv"].(types.TypeAndValue), true
+}
+
+func IsIntegerLiteral(pass *analysis.Pass, node ast.Node, value constant.Value) bool {
+	tv, ok := IntegerLiteral(pass, node)
+	if !ok {
+		return false
+	}
+	return constant.Compare(tv.Value, token.EQL, value)
+}

vendor/honnef.co/go/tools/analysis/code/visit.go

@@ -0,0 +1,51 @@
+package code
+
+import (
+	"bytes"
+	"go/ast"
+	"go/format"
+
+	"honnef.co/go/tools/pattern"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+func Preorder(pass *analysis.Pass, fn func(ast.Node), types ...ast.Node) {
+	pass.ResultOf[inspect.Analyzer].(*inspector.Inspector).Preorder(types, fn)
+}
+
+func PreorderStack(pass *analysis.Pass, fn func(ast.Node, []ast.Node), types ...ast.Node) {
+	pass.ResultOf[inspect.Analyzer].(*inspector.Inspector).WithStack(types, func(n ast.Node, push bool, stack []ast.Node) (proceed bool) {
+		if push {
+			fn(n, stack)
+		}
+		return true
+	})
+}
+
+func Match(pass *analysis.Pass, q pattern.Pattern, node ast.Node) (*pattern.Matcher, bool) {
+	// Note that we ignore q.Relevant – callers of Match usually use
+	// AST inspectors that already filter on nodes we're interested
+	// in.
+	m := &pattern.Matcher{TypesInfo: pass.TypesInfo}
+	ok := m.Match(q.Root, node)
+	return m, ok
+}
+
+func MatchAndEdit(pass *analysis.Pass, before, after pattern.Pattern, node ast.Node) (*pattern.Matcher, []analysis.TextEdit, bool) {
+	m, ok := Match(pass, before, node)
+	if !ok {
+		return m, nil, false
+	}
+	r := pattern.NodeToAST(after.Root, m.State)
+	buf := &bytes.Buffer{}
+	format.Node(buf, pass.Fset, r)
+	edit := []analysis.TextEdit{{
+		Pos:     node.Pos(),
+		End:     node.End(),
+		NewText: buf.Bytes(),
+	}}
+	return m, edit, true
+}

vendor/honnef.co/go/tools/analysis/edit/edit.go

@@ -0,0 +1,83 @@
+// Package edit contains helpers for creating suggested fixes.
+package edit
+
+import (
+	"bytes"
+	"go/ast"
+	"go/format"
+	"go/token"
+
+	"golang.org/x/tools/go/analysis"
+	"honnef.co/go/tools/pattern"
+)
+
+// Ranger describes values that have a start and end position.
+// In most cases these are either ast.Node or manually constructed ranges.
+type Ranger interface {
+	Pos() token.Pos
+	End() token.Pos
+}
+
+// Range implements the Ranger interface.
+type Range [2]token.Pos
+
+func (r Range) Pos() token.Pos { return r[0] }
+func (r Range) End() token.Pos { return r[1] }
+
+// ReplaceWithString replaces a range with a string.
+func ReplaceWithString(old Ranger, new string) analysis.TextEdit {
+	return analysis.TextEdit{
+		Pos:     old.Pos(),
+		End:     old.End(),
+		NewText: []byte(new),
+	}
+}
+
+// ReplaceWithNode replaces a range with an AST node.
+func ReplaceWithNode(fset *token.FileSet, old Ranger, new ast.Node) analysis.TextEdit {
+	buf := &bytes.Buffer{}
+	if err := format.Node(buf, fset, new); err != nil {
+		panic("internal error: " + err.Error())
+	}
+	return analysis.TextEdit{
+		Pos:     old.Pos(),
+		End:     old.End(),
+		NewText: buf.Bytes(),
+	}
+}
+
+// ReplaceWithPattern replaces a range with the result of executing a pattern.
+func ReplaceWithPattern(fset *token.FileSet, old Ranger, new pattern.Pattern, state pattern.State) analysis.TextEdit {
+	r := pattern.NodeToAST(new.Root, state)
+	buf := &bytes.Buffer{}
+	format.Node(buf, fset, r)
+	return analysis.TextEdit{
+		Pos:     old.Pos(),
+		End:     old.End(),
+		NewText: buf.Bytes(),
+	}
+}
+
+// Delete deletes a range of code.
+func Delete(old Ranger) analysis.TextEdit {
+	return analysis.TextEdit{
+		Pos:     old.Pos(),
+		End:     old.End(),
+		NewText: nil,
+	}
+}
+
+func Fix(msg string, edits ...analysis.TextEdit) analysis.SuggestedFix {
+	return analysis.SuggestedFix{
+		Message:   msg,
+		TextEdits: edits,
+	}
+}
+
+// Selector creates a new selector expression.
+func Selector(x, sel string) *ast.SelectorExpr {
+	return &ast.SelectorExpr{
+		X:   &ast.Ident{Name: x},
+		Sel: &ast.Ident{Name: sel},
+	}
+}

vendor/honnef.co/go/tools/analysis/facts/deprecated.go

@@ -0,0 +1,145 @@
+package facts
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+	"reflect"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+type IsDeprecated struct{ Msg string }
+
+func (*IsDeprecated) AFact()           {}
+func (d *IsDeprecated) String() string { return "Deprecated: " + d.Msg }
+
+type DeprecatedResult struct {
+	Objects  map[types.Object]*IsDeprecated
+	Packages map[*types.Package]*IsDeprecated
+}
+
+var Deprecated = &analysis.Analyzer{
+	Name:       "fact_deprecated",
+	Doc:        "Mark deprecated objects",
+	Run:        deprecated,
+	FactTypes:  []analysis.Fact{(*IsDeprecated)(nil)},
+	ResultType: reflect.TypeOf(DeprecatedResult{}),
+}
+
+func deprecated(pass *analysis.Pass) (interface{}, error) {
+	var names []*ast.Ident
+
+	extractDeprecatedMessage := func(docs []*ast.CommentGroup) string {
+		for _, doc := range docs {
+			if doc == nil {
+				continue
+			}
+			parts := strings.Split(doc.Text(), "\n\n")
+			for _, part := range parts {
+				if !strings.HasPrefix(part, "Deprecated: ") {
+					continue
+				}
+				alt := part[len("Deprecated: "):]
+				alt = strings.Replace(alt, "\n", " ", -1)
+				return alt
+			}
+		}
+		return ""
+	}
+	doDocs := func(names []*ast.Ident, docs []*ast.CommentGroup) {
+		alt := extractDeprecatedMessage(docs)
+		if alt == "" {
+			return
+		}
+
+		for _, name := range names {
+			obj := pass.TypesInfo.ObjectOf(name)
+			pass.ExportObjectFact(obj, &IsDeprecated{alt})
+		}
+	}
+
+	var docs []*ast.CommentGroup
+	for _, f := range pass.Files {
+		docs = append(docs, f.Doc)
+	}
+	if alt := extractDeprecatedMessage(docs); alt != "" {
+		// Don't mark package syscall as deprecated, even though
+		// it is. A lot of people still use it for simple
+		// constants like SIGKILL, and I am not comfortable
+		// telling them to use x/sys for that.
+		if pass.Pkg.Path() != "syscall" {
+			pass.ExportPackageFact(&IsDeprecated{alt})
+		}
+	}
+
+	docs = docs[:0]
+	for _, f := range pass.Files {
+		fn := func(node ast.Node) bool {
+			if node == nil {
+				return true
+			}
+			var ret bool
+			switch node := node.(type) {
+			case *ast.GenDecl:
+				switch node.Tok {
+				case token.TYPE, token.CONST, token.VAR:
+					docs = append(docs, node.Doc)
+					return true
+				default:
+					return false
+				}
+			case *ast.FuncDecl:
+				docs = append(docs, node.Doc)
+				names = []*ast.Ident{node.Name}
+				ret = false
+			case *ast.TypeSpec:
+				docs = append(docs, node.Doc)
+				names = []*ast.Ident{node.Name}
+				ret = true
+			case *ast.ValueSpec:
+				docs = append(docs, node.Doc)
+				names = node.Names
+				ret = false
+			case *ast.File:
+				return true
+			case *ast.StructType:
+				for _, field := range node.Fields.List {
+					doDocs(field.Names, []*ast.CommentGroup{field.Doc})
+				}
+				return false
+			case *ast.InterfaceType:
+				for _, field := range node.Methods.List {
+					doDocs(field.Names, []*ast.CommentGroup{field.Doc})
+				}
+				return false
+			default:
+				return false
+			}
+			if len(names) == 0 || len(docs) == 0 {
+				return ret
+			}
+			doDocs(names, docs)
+
+			docs = docs[:0]
+			names = nil
+			return ret
+		}
+		ast.Inspect(f, fn)
+	}
+
+	out := DeprecatedResult{
+		Objects:  map[types.Object]*IsDeprecated{},
+		Packages: map[*types.Package]*IsDeprecated{},
+	}
+
+	for _, fact := range pass.AllObjectFacts() {
+		out.Objects[fact.Object] = fact.Fact.(*IsDeprecated)
+	}
+	for _, fact := range pass.AllPackageFacts() {
+		out.Packages[fact.Package] = fact.Fact.(*IsDeprecated)
+	}
+
+	return out, nil
+}

vendor/honnef.co/go/tools/analysis/facts/directives.go

@@ -0,0 +1,20 @@
+package facts
+
+import (
+	"reflect"
+
+	"golang.org/x/tools/go/analysis"
+	"honnef.co/go/tools/analysis/lint"
+)
+
+func directives(pass *analysis.Pass) (interface{}, error) {
+	return lint.ParseDirectives(pass.Files, pass.Fset), nil
+}
+
+var Directives = &analysis.Analyzer{
+	Name:             "directives",
+	Doc:              "extracts linter directives",
+	Run:              directives,
+	RunDespiteErrors: true,
+	ResultType:       reflect.TypeOf([]lint.Directive{}),
+}

vendor/honnef.co/go/tools/analysis/facts/generated.go

@@ -0,0 +1,97 @@
+package facts
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"os"
+	"reflect"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+type Generator int
+
+// A list of known generators we can detect
+const (
+	Unknown Generator = iota
+	Goyacc
+	Cgo
+	Stringer
+	ProtocGenGo
+)
+
+var (
+	// used by cgo before Go 1.11
+	oldCgo = []byte("// Created by cgo - DO NOT EDIT")
+	prefix = []byte("// Code generated ")
+	suffix = []byte(" DO NOT EDIT.")
+	nl     = []byte("\n")
+	crnl   = []byte("\r\n")
+)
+
+func isGenerated(path string) (Generator, bool) {
+	f, err := os.Open(path)
+	if err != nil {
+		return 0, false
+	}
+	defer f.Close()
+	br := bufio.NewReader(f)
+	for {
+		s, err := br.ReadBytes('\n')
+		if err != nil && err != io.EOF {
+			return 0, false
+		}
+		s = bytes.TrimSuffix(s, crnl)
+		s = bytes.TrimSuffix(s, nl)
+		if bytes.HasPrefix(s, prefix) && bytes.HasSuffix(s, suffix) {
+			if len(s)-len(suffix) < len(prefix) {
+				return Unknown, true
+			}
+
+			text := string(s[len(prefix) : len(s)-len(suffix)])
+			switch text {
+			case "by goyacc.":
+				return Goyacc, true
+			case "by cmd/cgo;":
+				return Cgo, true
+			case "by protoc-gen-go.":
+				return ProtocGenGo, true
+			}
+			if strings.HasPrefix(text, `by "stringer `) {
+				return Stringer, true
+			}
+			if strings.HasPrefix(text, `by goyacc `) {
+				return Goyacc, true
+			}
+
+			return Unknown, true
+		}
+		if bytes.Equal(s, oldCgo) {
+			return Cgo, true
+		}
+		if err == io.EOF {
+			break
+		}
+	}
+	return 0, false
+}
+
+var Generated = &analysis.Analyzer{
+	Name: "isgenerated",
+	Doc:  "annotate file names that have been code generated",
+	Run: func(pass *analysis.Pass) (interface{}, error) {
+		m := map[string]Generator{}
+		for _, f := range pass.Files {
+			path := pass.Fset.PositionFor(f.Pos(), false).Filename
+			g, ok := isGenerated(path)
+			if ok {
+				m[path] = g
+			}
+		}
+		return m, nil
+	},
+	RunDespiteErrors: true,
+	ResultType:       reflect.TypeOf(map[string]Generator{}),
+}

vendor/honnef.co/go/tools/analysis/facts/nilness/nilness.go

@@ -0,0 +1,251 @@
+package nilness
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+	"reflect"
+
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/go/types/typeutil"
+	"honnef.co/go/tools/internal/passes/buildir"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+// neverReturnsNilFact denotes that a function's return value will never
+// be nil (typed or untyped). The analysis errs on the side of false
+// negatives.
+type neverReturnsNilFact struct {
+	Rets []neverNilness
+}
+
+func (*neverReturnsNilFact) AFact() {}
+func (fact *neverReturnsNilFact) String() string {
+	return fmt.Sprintf("never returns nil: %v", fact.Rets)
+}
+
+type Result struct {
+	m map[*types.Func][]neverNilness
+}
+
+var Analysis = &analysis.Analyzer{
+	Name:       "nilness",
+	Doc:        "Annotates return values that will never be nil (typed or untyped)",
+	Run:        run,
+	Requires:   []*analysis.Analyzer{buildir.Analyzer},
+	FactTypes:  []analysis.Fact{(*neverReturnsNilFact)(nil)},
+	ResultType: reflect.TypeOf((*Result)(nil)),
+}
+
+// MayReturnNil reports whether the ret's return value of fn might be
+// a typed or untyped nil value. The value of ret is zero-based. When
+// globalOnly is true, the only possible nil values are global
+// variables.
+//
+// The analysis has false positives: MayReturnNil can incorrectly
+// report true, but never incorrectly reports false.
+func (r *Result) MayReturnNil(fn *types.Func, ret int) (yes bool, globalOnly bool) {
+	if !typeutil.IsPointerLike(fn.Type().(*types.Signature).Results().At(ret).Type()) {
+		return false, false
+	}
+	if len(r.m[fn]) == 0 {
+		return true, false
+	}
+
+	v := r.m[fn][ret]
+	return v != neverNil, v == onlyGlobal
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	seen := map[*ir.Function]struct{}{}
+	out := &Result{
+		m: map[*types.Func][]neverNilness{},
+	}
+	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
+		impl(pass, fn, seen)
+	}
+
+	for _, fact := range pass.AllObjectFacts() {
+		out.m[fact.Object.(*types.Func)] = fact.Fact.(*neverReturnsNilFact).Rets
+	}
+
+	return out, nil
+}
+
+type neverNilness uint8
+
+const (
+	neverNil   neverNilness = 1
+	onlyGlobal neverNilness = 2
+	nilly      neverNilness = 3
+)
+
+func (n neverNilness) String() string {
+	switch n {
+	case neverNil:
+		return "never"
+	case onlyGlobal:
+		return "global"
+	case nilly:
+		return "nil"
+	default:
+		return "BUG"
+	}
+}
+
+func impl(pass *analysis.Pass, fn *ir.Function, seenFns map[*ir.Function]struct{}) []neverNilness {
+	if fn.Object() == nil {
+		// TODO(dh): support closures
+		return nil
+	}
+	if fact := new(neverReturnsNilFact); pass.ImportObjectFact(fn.Object(), fact) {
+		return fact.Rets
+	}
+	if fn.Pkg != pass.ResultOf[buildir.Analyzer].(*buildir.IR).Pkg {
+		return nil
+	}
+	if fn.Blocks == nil {
+		return nil
+	}
+	if _, ok := seenFns[fn]; ok {
+		// break recursion
+		return nil
+	}
+
+	seenFns[fn] = struct{}{}
+
+	seen := map[ir.Value]struct{}{}
+
+	var mightReturnNil func(v ir.Value) neverNilness
+	mightReturnNil = func(v ir.Value) neverNilness {
+		if _, ok := seen[v]; ok {
+			// break cycle
+			return nilly
+		}
+		if !typeutil.IsPointerLike(v.Type()) {
+			return neverNil
+		}
+		seen[v] = struct{}{}
+		switch v := v.(type) {
+		case *ir.MakeInterface:
+			return mightReturnNil(v.X)
+		case *ir.Convert:
+			return mightReturnNil(v.X)
+		case *ir.SliceToArrayPointer:
+			if typeutil.CoreType(v.Type()).(*types.Pointer).Elem().Underlying().(*types.Array).Len() == 0 {
+				return mightReturnNil(v.X)
+			} else {
+				// converting a slice to an array pointer of length > 0 panics if the slice is nil
+				return neverNil
+			}
+		case *ir.Slice:
+			return mightReturnNil(v.X)
+		case *ir.Phi:
+			ret := neverNil
+			for _, e := range v.Edges {
+				if n := mightReturnNil(e); n > ret {
+					ret = n
+				}
+			}
+			return ret
+		case *ir.Extract:
+			switch d := v.Tuple.(type) {
+			case *ir.Call:
+				if callee := d.Call.StaticCallee(); callee != nil {
+					ret := impl(pass, callee, seenFns)
+					if len(ret) == 0 {
+						return nilly
+					}
+					return ret[v.Index]
+				} else {
+					return nilly
+				}
+			case *ir.TypeAssert, *ir.Next, *ir.Select, *ir.MapLookup, *ir.TypeSwitch, *ir.Recv, *ir.Sigma:
+				// we don't need to look at the Extract's index
+				// because we've already checked its type.
+				return nilly
+			default:
+				panic(fmt.Sprintf("internal error: unhandled type %T", d))
+			}
+		case *ir.Call:
+			if callee := v.Call.StaticCallee(); callee != nil {
+				ret := impl(pass, callee, seenFns)
+				if len(ret) == 0 {
+					return nilly
+				}
+				return ret[0]
+			} else {
+				return nilly
+			}
+		case *ir.BinOp, *ir.UnOp, *ir.Alloc, *ir.FieldAddr, *ir.IndexAddr, *ir.Global, *ir.MakeSlice, *ir.MakeClosure, *ir.Function, *ir.MakeMap, *ir.MakeChan:
+			return neverNil
+		case *ir.Sigma:
+			iff, ok := v.From.Control().(*ir.If)
+			if !ok {
+				return nilly
+			}
+			binop, ok := iff.Cond.(*ir.BinOp)
+			if !ok {
+				return nilly
+			}
+			isNil := func(v ir.Value) bool {
+				k, ok := v.(*ir.Const)
+				if !ok {
+					return false
+				}
+				return k.Value == nil
+			}
+			if binop.X == v.X && isNil(binop.Y) || binop.Y == v.X && isNil(binop.X) {
+				op := binop.Op
+				if v.From.Succs[0] != v.Block() {
+					// we're in the false branch, negate op
+					switch op {
+					case token.EQL:
+						op = token.NEQ
+					case token.NEQ:
+						op = token.EQL
+					default:
+						panic(fmt.Sprintf("internal error: unhandled token %v", op))
+					}
+				}
+				switch op {
+				case token.EQL:
+					return nilly
+				case token.NEQ:
+					return neverNil
+				default:
+					panic(fmt.Sprintf("internal error: unhandled token %v", op))
+				}
+			}
+			return nilly
+		case *ir.ChangeType:
+			return mightReturnNil(v.X)
+		case *ir.Load:
+			if _, ok := v.X.(*ir.Global); ok {
+				return onlyGlobal
+			}
+			return nilly
+		case *ir.AggregateConst:
+			return neverNil
+		case *ir.TypeAssert, *ir.ChangeInterface, *ir.Field, *ir.Const, *ir.GenericConst, *ir.Index, *ir.MapLookup, *ir.Parameter, *ir.Recv, *ir.TypeSwitch:
+			return nilly
+		default:
+			panic(fmt.Sprintf("internal error: unhandled type %T", v))
+		}
+	}
+	ret := fn.Exit.Control().(*ir.Return)
+	out := make([]neverNilness, len(ret.Results))
+	export := false
+	for i, v := range ret.Results {
+		v := mightReturnNil(v)
+		out[i] = v
+		if v != nilly && typeutil.IsPointerLike(fn.Signature.Results().At(i).Type()) {
+			export = true
+		}
+	}
+	if export {
+		pass.ExportObjectFact(fn.Object(), &neverReturnsNilFact{out})
+	}
+	return out
+}

vendor/honnef.co/go/tools/analysis/facts/purity.go

@@ -0,0 +1,178 @@
+package facts
+
+import (
+	"go/types"
+	"reflect"
+
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/go/ir/irutil"
+	"honnef.co/go/tools/internal/passes/buildir"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+type IsPure struct{}
+
+func (*IsPure) AFact()           {}
+func (d *IsPure) String() string { return "is pure" }
+
+type PurityResult map[*types.Func]*IsPure
+
+var Purity = &analysis.Analyzer{
+	Name:       "fact_purity",
+	Doc:        "Mark pure functions",
+	Run:        purity,
+	Requires:   []*analysis.Analyzer{buildir.Analyzer},
+	FactTypes:  []analysis.Fact{(*IsPure)(nil)},
+	ResultType: reflect.TypeOf(PurityResult{}),
+}
+
+var pureStdlib = map[string]struct{}{
+	"errors.New":                      {},
+	"fmt.Errorf":                      {},
+	"fmt.Sprintf":                     {},
+	"fmt.Sprint":                      {},
+	"sort.Reverse":                    {},
+	"strings.Map":                     {},
+	"strings.Repeat":                  {},
+	"strings.Replace":                 {},
+	"strings.Title":                   {},
+	"strings.ToLower":                 {},
+	"strings.ToLowerSpecial":          {},
+	"strings.ToTitle":                 {},
+	"strings.ToTitleSpecial":          {},
+	"strings.ToUpper":                 {},
+	"strings.ToUpperSpecial":          {},
+	"strings.Trim":                    {},
+	"strings.TrimFunc":                {},
+	"strings.TrimLeft":                {},
+	"strings.TrimLeftFunc":            {},
+	"strings.TrimPrefix":              {},
+	"strings.TrimRight":               {},
+	"strings.TrimRightFunc":           {},
+	"strings.TrimSpace":               {},
+	"strings.TrimSuffix":              {},
+	"(*net/http.Request).WithContext": {},
+}
+
+func purity(pass *analysis.Pass) (interface{}, error) {
+	seen := map[*ir.Function]struct{}{}
+	irpkg := pass.ResultOf[buildir.Analyzer].(*buildir.IR).Pkg
+	var check func(fn *ir.Function) (ret bool)
+	check = func(fn *ir.Function) (ret bool) {
+		if fn.Object() == nil {
+			// TODO(dh): support closures
+			return false
+		}
+		if pass.ImportObjectFact(fn.Object(), new(IsPure)) {
+			return true
+		}
+		if fn.Pkg != irpkg {
+			// Function is in another package but wasn't marked as
+			// pure, ergo it isn't pure
+			return false
+		}
+		// Break recursion
+		if _, ok := seen[fn]; ok {
+			return false
+		}
+
+		seen[fn] = struct{}{}
+		defer func() {
+			if ret {
+				pass.ExportObjectFact(fn.Object(), &IsPure{})
+			}
+		}()
+
+		if irutil.IsStub(fn) {
+			return false
+		}
+
+		if _, ok := pureStdlib[fn.Object().(*types.Func).FullName()]; ok {
+			return true
+		}
+
+		if fn.Signature.Results().Len() == 0 {
+			// A function with no return values is empty or is doing some
+			// work we cannot see (for example because of build tags);
+			// don't consider it pure.
+			return false
+		}
+
+		for _, param := range fn.Params {
+			// TODO(dh): this may not be strictly correct. pure code
+			// can, to an extent, operate on non-basic types.
+			if _, ok := param.Type().Underlying().(*types.Basic); !ok {
+				return false
+			}
+		}
+
+		// Don't consider external functions pure.
+		if fn.Blocks == nil {
+			return false
+		}
+		checkCall := func(common *ir.CallCommon) bool {
+			if common.IsInvoke() {
+				return false
+			}
+			builtin, ok := common.Value.(*ir.Builtin)
+			if !ok {
+				if common.StaticCallee() != fn {
+					if common.StaticCallee() == nil {
+						return false
+					}
+					if !check(common.StaticCallee()) {
+						return false
+					}
+				}
+			} else {
+				switch builtin.Name() {
+				case "len", "cap":
+				default:
+					return false
+				}
+			}
+			return true
+		}
+		for _, b := range fn.Blocks {
+			for _, ins := range b.Instrs {
+				switch ins := ins.(type) {
+				case *ir.Call:
+					if !checkCall(ins.Common()) {
+						return false
+					}
+				case *ir.Defer:
+					if !checkCall(&ins.Call) {
+						return false
+					}
+				case *ir.Select:
+					return false
+				case *ir.Send:
+					return false
+				case *ir.Go:
+					return false
+				case *ir.Panic:
+					return false
+				case *ir.Store:
+					return false
+				case *ir.FieldAddr:
+					return false
+				case *ir.Alloc:
+					return false
+				case *ir.Load:
+					return false
+				}
+			}
+		}
+		return true
+	}
+	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
+		check(fn)
+	}
+
+	out := PurityResult{}
+	for _, fact := range pass.AllObjectFacts() {
+		out[fact.Object.(*types.Func)] = fact.Fact.(*IsPure)
+	}
+	return out, nil
+}

vendor/honnef.co/go/tools/analysis/facts/token.go

@@ -0,0 +1,24 @@
+package facts
+
+import (
+	"go/ast"
+	"go/token"
+	"reflect"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var TokenFile = &analysis.Analyzer{
+	Name: "tokenfileanalyzer",
+	Doc:  "creates a mapping of *token.File to *ast.File",
+	Run: func(pass *analysis.Pass) (interface{}, error) {
+		m := map[*token.File]*ast.File{}
+		for _, af := range pass.Files {
+			tf := pass.Fset.File(af.Pos())
+			m[tf] = af
+		}
+		return m, nil
+	},
+	RunDespiteErrors: true,
+	ResultType:       reflect.TypeOf(map[*token.File]*ast.File{}),
+}

vendor/honnef.co/go/tools/analysis/facts/typedness/typedness.go

@@ -0,0 +1,253 @@
+package typedness
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+	"reflect"
+
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/go/ir/irutil"
+	"honnef.co/go/tools/internal/passes/buildir"
+
+	"golang.org/x/exp/typeparams"
+	"golang.org/x/tools/go/analysis"
+)
+
+// alwaysTypedFact denotes that a function's return value will never
+// be untyped nil. The analysis errs on the side of false negatives.
+type alwaysTypedFact struct {
+	Rets uint8
+}
+
+func (*alwaysTypedFact) AFact() {}
+func (fact *alwaysTypedFact) String() string {
+	return fmt.Sprintf("always typed: %08b", fact.Rets)
+}
+
+type Result struct {
+	m map[*types.Func]uint8
+}
+
+var Analysis = &analysis.Analyzer{
+	Name:       "typedness",
+	Doc:        "Annotates return values that are always typed values",
+	Run:        run,
+	Requires:   []*analysis.Analyzer{buildir.Analyzer},
+	FactTypes:  []analysis.Fact{(*alwaysTypedFact)(nil)},
+	ResultType: reflect.TypeOf((*Result)(nil)),
+}
+
+// MustReturnTyped reports whether the ret's return value of fn must
+// be a typed value, i.e. an interface value containing a concrete
+// type or trivially a concrete type. The value of ret is zero-based.
+//
+// The analysis has false negatives: MustReturnTyped may incorrectly
+// report false, but never incorrectly reports true.
+func (r *Result) MustReturnTyped(fn *types.Func, ret int) bool {
+	if _, ok := fn.Type().(*types.Signature).Results().At(ret).Type().Underlying().(*types.Interface); !ok {
+		return true
+	}
+	return (r.m[fn] & (1 << ret)) != 0
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	seen := map[*ir.Function]struct{}{}
+	out := &Result{
+		m: map[*types.Func]uint8{},
+	}
+	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
+		impl(pass, fn, seen)
+	}
+
+	for _, fact := range pass.AllObjectFacts() {
+		out.m[fact.Object.(*types.Func)] = fact.Fact.(*alwaysTypedFact).Rets
+	}
+
+	return out, nil
+}
+
+func impl(pass *analysis.Pass, fn *ir.Function, seenFns map[*ir.Function]struct{}) (out uint8) {
+	if fn.Signature.Results().Len() > 8 {
+		return 0
+	}
+	if fn.Object() == nil {
+		// TODO(dh): support closures
+		return 0
+	}
+	if fact := new(alwaysTypedFact); pass.ImportObjectFact(fn.Object(), fact) {
+		return fact.Rets
+	}
+	if fn.Pkg != pass.ResultOf[buildir.Analyzer].(*buildir.IR).Pkg {
+		return 0
+	}
+	if fn.Blocks == nil {
+		return 0
+	}
+	if irutil.IsStub(fn) {
+		return 0
+	}
+	if _, ok := seenFns[fn]; ok {
+		// break recursion
+		return 0
+	}
+
+	seenFns[fn] = struct{}{}
+	defer func() {
+		for i := 0; i < fn.Signature.Results().Len(); i++ {
+			if _, ok := fn.Signature.Results().At(i).Type().Underlying().(*types.Interface); !ok {
+				// we don't need facts to know that non-interface
+				// types can't be untyped nil. zeroing out those bits
+				// may result in all bits being zero, in which case we
+				// don't have to save any fact.
+				out &= ^(1 << i)
+			}
+		}
+		if out > 0 {
+			pass.ExportObjectFact(fn.Object(), &alwaysTypedFact{out})
+		}
+	}()
+
+	isUntypedNil := func(v ir.Value) bool {
+		k, ok := v.(*ir.Const)
+		if !ok {
+			return false
+		}
+		if _, ok := k.Type().Underlying().(*types.Interface); !ok {
+			return false
+		}
+		return k.Value == nil
+	}
+
+	var do func(v ir.Value, seen map[ir.Value]struct{}) bool
+	do = func(v ir.Value, seen map[ir.Value]struct{}) bool {
+		if _, ok := seen[v]; ok {
+			// break cycle
+			return false
+		}
+		seen[v] = struct{}{}
+		switch v := v.(type) {
+		case *ir.Const:
+			// can't be a typed nil, because then we'd be returning the
+			// result of MakeInterface.
+			return false
+		case *ir.ChangeInterface:
+			return do(v.X, seen)
+		case *ir.Extract:
+			call, ok := v.Tuple.(*ir.Call)
+			if !ok {
+				// We only care about extracts of function results. For
+				// everything else (e.g. channel receives and map
+				// lookups), we can either not deduce any information, or
+				// will see a MakeInterface.
+				return false
+			}
+			if callee := call.Call.StaticCallee(); callee != nil {
+				return impl(pass, callee, seenFns)&(1<<v.Index) != 0
+			} else {
+				// we don't know what function we're calling. no need
+				// to look at the signature, though. if it weren't an
+				// interface, we'd be seeing a MakeInterface
+				// instruction.
+				return false
+			}
+		case *ir.Call:
+			if callee := v.Call.StaticCallee(); callee != nil {
+				return impl(pass, callee, seenFns)&1 != 0
+			} else {
+				// we don't know what function we're calling. no need
+				// to look at the signature, though. if it weren't an
+				// interface, we'd be seeing a MakeInterface
+				// instruction.
+				return false
+			}
+		case *ir.Sigma:
+			iff, ok := v.From.Control().(*ir.If)
+			if !ok {
+				// give up
+				return false
+			}
+
+			binop, ok := iff.Cond.(*ir.BinOp)
+			if !ok {
+				// give up
+				return false
+			}
+
+			if (binop.X == v.X && isUntypedNil(binop.Y)) || (isUntypedNil(binop.X) && binop.Y == v.X) {
+				op := binop.Op
+				if v.From.Succs[0] != v.Block() {
+					// we're in the false branch, negate op
+					switch op {
+					case token.EQL:
+						op = token.NEQ
+					case token.NEQ:
+						op = token.EQL
+					default:
+						panic(fmt.Sprintf("internal error: unhandled token %v", op))
+					}
+				}
+
+				switch op {
+				case token.EQL:
+					// returned value equals untyped nil
+					return false
+				case token.NEQ:
+					// returned value does not equal untyped nil
+					return true
+				default:
+					panic(fmt.Sprintf("internal error: unhandled token %v", op))
+				}
+			}
+
+			// TODO(dh): handle comparison with typed nil
+
+			// give up
+			return false
+		case *ir.Phi:
+			for _, pv := range v.Edges {
+				if !do(pv, seen) {
+					return false
+				}
+			}
+			return true
+		case *ir.MakeInterface:
+			terms, err := typeparams.NormalTerms(v.X.Type())
+			if len(terms) == 0 || err != nil {
+				// Type is a type parameter with no type terms (or we couldn't determine the terms). Such a type
+				// _can_ be nil when put in an interface value.
+				//
+				// There is no instruction that can create a guaranteed non-nil instance of a type parameter without
+				// type constraints, so we return false right away, without checking v.X's typedness.
+				return false
+			}
+			return true
+		case *ir.TypeAssert:
+			// type assertions fail for untyped nils. Either we have a
+			// single lhs and the type assertion succeeds or panics,
+			// or we have two lhs and we'll return Extract instead.
+			return true
+		case *ir.ChangeType:
+			// we'll only see interface->interface conversions, which
+			// don't tell us anything about the nilness.
+			return false
+		case *ir.MapLookup, *ir.Index, *ir.Recv, *ir.Parameter, *ir.Load, *ir.Field:
+			// All other instructions that tell us nothing about the
+			// typedness of interface values.
+			return false
+		default:
+			panic(fmt.Sprintf("internal error: unhandled type %T", v))
+		}
+	}
+
+	ret := fn.Exit.Control().(*ir.Return)
+	for i, v := range ret.Results {
+		typ := fn.Signature.Results().At(i).Type()
+		if _, ok := typ.Underlying().(*types.Interface); ok && !typeparams.IsTypeParam(typ) {
+			if do(v, map[ir.Value]struct{}{}) {
+				out |= 1 << i
+			}
+		}
+	}
+	return out
+}

vendor/honnef.co/go/tools/analysis/lint/lint.go

@@ -0,0 +1,283 @@
+// Package lint provides abstractions on top of go/analysis.
+// These abstractions add extra information to analyzes, such as structured documentation and severities.
+package lint
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/token"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+// Analyzer wraps a go/analysis.Analyzer and provides structured documentation.
+type Analyzer struct {
+	// The analyzer's documentation. Unlike go/analysis.Analyzer.Doc,
+	// this field is structured, providing access to severity, options
+	// etc.
+	Doc      *Documentation
+	Analyzer *analysis.Analyzer
+}
+
+func (a *Analyzer) initialize() {
+	a.Analyzer.Doc = a.Doc.String()
+	if a.Analyzer.Flags.Usage == nil {
+		fs := flag.NewFlagSet("", flag.PanicOnError)
+		fs.Var(newVersionFlag(), "go", "Target Go version")
+		a.Analyzer.Flags = *fs
+	}
+}
+
+// InitializeAnalyzers takes a map of documentation and a map of go/analysis.Analyzers and returns a slice of Analyzers.
+// The map keys are the analyzer names.
+func InitializeAnalyzers(docs map[string]*Documentation, analyzers map[string]*analysis.Analyzer) []*Analyzer {
+	out := make([]*Analyzer, 0, len(analyzers))
+	for k, v := range analyzers {
+		v.Name = k
+		a := &Analyzer{
+			Doc:      docs[k],
+			Analyzer: v,
+		}
+		a.initialize()
+		out = append(out, a)
+	}
+	return out
+}
+
+// Severity describes the severity of diagnostics reported by an analyzer.
+type Severity int
+
+const (
+	SeverityNone Severity = iota
+	SeverityError
+	SeverityDeprecated
+	SeverityWarning
+	SeverityInfo
+	SeverityHint
+)
+
+// MergeStrategy sets how merge mode should behave for diagnostics of an analyzer.
+type MergeStrategy int
+
+const (
+	MergeIfAny MergeStrategy = iota
+	MergeIfAll
+)
+
+type RawDocumentation struct {
+	Title      string
+	Text       string
+	Before     string
+	After      string
+	Since      string
+	NonDefault bool
+	Options    []string
+	Severity   Severity
+	MergeIf    MergeStrategy
+}
+
+type Documentation struct {
+	Title string
+	Text  string
+
+	TitleMarkdown string
+	TextMarkdown  string
+
+	Before     string
+	After      string
+	Since      string
+	NonDefault bool
+	Options    []string
+	Severity   Severity
+	MergeIf    MergeStrategy
+}
+
+func Markdownify(m map[string]*RawDocumentation) map[string]*Documentation {
+	out := make(map[string]*Documentation, len(m))
+	for k, v := range m {
+		out[k] = &Documentation{
+			Title: strings.TrimSpace(stripMarkdown(v.Title)),
+			Text:  strings.TrimSpace(stripMarkdown(v.Text)),
+
+			TitleMarkdown: strings.TrimSpace(toMarkdown(v.Title)),
+			TextMarkdown:  strings.TrimSpace(toMarkdown(v.Text)),
+
+			Before:     strings.TrimSpace(v.Before),
+			After:      strings.TrimSpace(v.After),
+			Since:      v.Since,
+			NonDefault: v.NonDefault,
+			Options:    v.Options,
+			Severity:   v.Severity,
+			MergeIf:    v.MergeIf,
+		}
+	}
+	return out
+}
+
+func toMarkdown(s string) string {
+	return strings.NewReplacer(`\'`, "`", `\"`, "`").Replace(s)
+}
+
+func stripMarkdown(s string) string {
+	return strings.NewReplacer(`\'`, "", `\"`, "'").Replace(s)
+}
+
+func (doc *Documentation) Format(metadata bool) string {
+	return doc.format(false, metadata)
+}
+
+func (doc *Documentation) FormatMarkdown(metadata bool) string {
+	return doc.format(true, metadata)
+}
+
+func (doc *Documentation) format(markdown bool, metadata bool) string {
+	b := &strings.Builder{}
+	if markdown {
+		fmt.Fprintf(b, "%s\n\n", doc.TitleMarkdown)
+		if doc.Text != "" {
+			fmt.Fprintf(b, "%s\n\n", doc.TextMarkdown)
+		}
+	} else {
+		fmt.Fprintf(b, "%s\n\n", doc.Title)
+		if doc.Text != "" {
+			fmt.Fprintf(b, "%s\n\n", doc.Text)
+		}
+	}
+
+	if doc.Before != "" {
+		fmt.Fprintln(b, "Before:")
+		fmt.Fprintln(b, "")
+		for _, line := range strings.Split(doc.Before, "\n") {
+			fmt.Fprint(b, "    ", line, "\n")
+		}
+		fmt.Fprintln(b, "")
+		fmt.Fprintln(b, "After:")
+		fmt.Fprintln(b, "")
+		for _, line := range strings.Split(doc.After, "\n") {
+			fmt.Fprint(b, "    ", line, "\n")
+		}
+		fmt.Fprintln(b, "")
+	}
+
+	if metadata {
+		fmt.Fprint(b, "Available since\n    ")
+		if doc.Since == "" {
+			fmt.Fprint(b, "unreleased")
+		} else {
+			fmt.Fprintf(b, "%s", doc.Since)
+		}
+		if doc.NonDefault {
+			fmt.Fprint(b, ", non-default")
+		}
+		fmt.Fprint(b, "\n")
+		if len(doc.Options) > 0 {
+			fmt.Fprintf(b, "\nOptions\n")
+			for _, opt := range doc.Options {
+				fmt.Fprintf(b, "    %s", opt)
+			}
+			fmt.Fprint(b, "\n")
+		}
+	}
+
+	return b.String()
+}
+
+func (doc *Documentation) String() string {
+	return doc.Format(true)
+}
+
+func newVersionFlag() flag.Getter {
+	tags := build.Default.ReleaseTags
+	v := tags[len(tags)-1][2:]
+	version := new(VersionFlag)
+	if err := version.Set(v); err != nil {
+		panic(fmt.Sprintf("internal error: %s", err))
+	}
+	return version
+}
+
+type VersionFlag int
+
+func (v *VersionFlag) String() string {
+	return fmt.Sprintf("1.%d", *v)
+}
+
+func (v *VersionFlag) Set(s string) error {
+	if len(s) < 3 {
+		return fmt.Errorf("invalid Go version: %q", s)
+	}
+	if s[0] != '1' {
+		return fmt.Errorf("invalid Go version: %q", s)
+	}
+	if s[1] != '.' {
+		return fmt.Errorf("invalid Go version: %q", s)
+	}
+	i, err := strconv.Atoi(s[2:])
+	if err != nil {
+		return fmt.Errorf("invalid Go version: %q", s)
+	}
+	*v = VersionFlag(i)
+	return nil
+}
+
+func (v *VersionFlag) Get() interface{} {
+	return int(*v)
+}
+
+// ExhaustiveTypeSwitch panics when called. It can be used to ensure
+// that type switches are exhaustive.
+func ExhaustiveTypeSwitch(v interface{}) {
+	panic(fmt.Sprintf("internal error: unhandled case %T", v))
+}
+
+// A directive is a comment of the form '//lint:<command>
+// [arguments...]'. It represents instructions to the static analysis
+// tool.
+type Directive struct {
+	Command   string
+	Arguments []string
+	Directive *ast.Comment
+	Node      ast.Node
+}
+
+func parseDirective(s string) (cmd string, args []string) {
+	if !strings.HasPrefix(s, "//lint:") {
+		return "", nil
+	}
+	s = strings.TrimPrefix(s, "//lint:")
+	fields := strings.Split(s, " ")
+	return fields[0], fields[1:]
+}
+
+// ParseDirectives extracts all directives from a list of Go files.
+func ParseDirectives(files []*ast.File, fset *token.FileSet) []Directive {
+	var dirs []Directive
+	for _, f := range files {
+		// OPT(dh): in our old code, we skip all the comment map work if we
+		// couldn't find any directives, benchmark if that's actually
+		// worth doing
+		cm := ast.NewCommentMap(fset, f, f.Comments)
+		for node, cgs := range cm {
+			for _, cg := range cgs {
+				for _, c := range cg.List {
+					if !strings.HasPrefix(c.Text, "//lint:") {
+						continue
+					}
+					cmd, args := parseDirective(c.Text)
+					d := Directive{
+						Command:   cmd,
+						Arguments: args,
+						Directive: c,
+						Node:      node,
+					}
+					dirs = append(dirs, d)
+				}
+			}
+		}
+	}
+	return dirs
+}

vendor/honnef.co/go/tools/analysis/report/report.go

@@ -0,0 +1,247 @@
+package report
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/format"
+	"go/token"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"honnef.co/go/tools/analysis/facts"
+	"honnef.co/go/tools/go/ast/astutil"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+type Options struct {
+	ShortRange      bool
+	FilterGenerated bool
+	Fixes           []analysis.SuggestedFix
+	Related         []analysis.RelatedInformation
+}
+
+type Option func(*Options)
+
+func ShortRange() Option {
+	return func(opts *Options) {
+		opts.ShortRange = true
+	}
+}
+
+func FilterGenerated() Option {
+	return func(opts *Options) {
+		opts.FilterGenerated = true
+	}
+}
+
+func Fixes(fixes ...analysis.SuggestedFix) Option {
+	return func(opts *Options) {
+		opts.Fixes = append(opts.Fixes, fixes...)
+	}
+}
+
+func Related(node Positioner, message string) Option {
+	return func(opts *Options) {
+		pos, end, ok := getRange(node, opts.ShortRange)
+		if !ok {
+			return
+		}
+		r := analysis.RelatedInformation{
+			Pos:     pos,
+			End:     end,
+			Message: message,
+		}
+		opts.Related = append(opts.Related, r)
+	}
+}
+
+type Positioner interface {
+	Pos() token.Pos
+}
+
+type fullPositioner interface {
+	Pos() token.Pos
+	End() token.Pos
+}
+
+type sourcer interface {
+	Source() ast.Node
+}
+
+// shortRange returns the position and end of the main component of an
+// AST node. For nodes that have no body, the short range is identical
+// to the node's Pos and End. For nodes that do have a body, the short
+// range excludes the body.
+func shortRange(node ast.Node) (pos, end token.Pos) {
+	switch node := node.(type) {
+	case *ast.File:
+		return node.Pos(), node.Name.End()
+	case *ast.CaseClause:
+		return node.Pos(), node.Colon + 1
+	case *ast.CommClause:
+		return node.Pos(), node.Colon + 1
+	case *ast.DeferStmt:
+		return node.Pos(), node.Defer + token.Pos(len("defer"))
+	case *ast.ExprStmt:
+		return shortRange(node.X)
+	case *ast.ForStmt:
+		if node.Post != nil {
+			return node.For, node.Post.End()
+		} else if node.Cond != nil {
+			return node.For, node.Cond.End()
+		} else if node.Init != nil {
+			// +1 to catch the semicolon, for gofmt'ed code
+			return node.Pos(), node.Init.End() + 1
+		} else {
+			return node.Pos(), node.For + token.Pos(len("for"))
+		}
+	case *ast.FuncDecl:
+		return node.Pos(), node.Type.End()
+	case *ast.FuncLit:
+		return node.Pos(), node.Type.End()
+	case *ast.GoStmt:
+		if _, ok := astutil.Unparen(node.Call.Fun).(*ast.FuncLit); ok {
+			return node.Pos(), node.Go + token.Pos(len("go"))
+		} else {
+			return node.Pos(), node.End()
+		}
+	case *ast.IfStmt:
+		return node.Pos(), node.Cond.End()
+	case *ast.RangeStmt:
+		return node.Pos(), node.X.End()
+	case *ast.SelectStmt:
+		return node.Pos(), node.Pos() + token.Pos(len("select"))
+	case *ast.SwitchStmt:
+		if node.Tag != nil {
+			return node.Pos(), node.Tag.End()
+		} else if node.Init != nil {
+			// +1 to catch the semicolon, for gofmt'ed code
+			return node.Pos(), node.Init.End() + 1
+		} else {
+			return node.Pos(), node.Pos() + token.Pos(len("switch"))
+		}
+	case *ast.TypeSwitchStmt:
+		return node.Pos(), node.Assign.End()
+	default:
+		return node.Pos(), node.End()
+	}
+}
+
+func HasRange(node Positioner) bool {
+	// we don't know if getRange will be called with shortRange set to
+	// true, so make sure that both work.
+	_, _, ok := getRange(node, false)
+	if !ok {
+		return false
+	}
+	_, _, ok = getRange(node, true)
+	return ok
+}
+
+func getRange(node Positioner, short bool) (pos, end token.Pos, ok bool) {
+	switch n := node.(type) {
+	case sourcer:
+		s := n.Source()
+		if s == nil {
+			return 0, 0, false
+		}
+		if short {
+			p, e := shortRange(s)
+			return p, e, true
+		}
+		return s.Pos(), s.End(), true
+	case fullPositioner:
+		if short {
+			p, e := shortRange(n)
+			return p, e, true
+		}
+		return n.Pos(), n.End(), true
+	default:
+		return n.Pos(), token.NoPos, true
+	}
+}
+
+func Report(pass *analysis.Pass, node Positioner, message string, opts ...Option) {
+	cfg := &Options{}
+	for _, opt := range opts {
+		opt(cfg)
+	}
+
+	file := DisplayPosition(pass.Fset, node.Pos()).Filename
+	if cfg.FilterGenerated {
+		m := pass.ResultOf[facts.Generated].(map[string]facts.Generator)
+		if _, ok := m[file]; ok {
+			return
+		}
+	}
+
+	pos, end, ok := getRange(node, cfg.ShortRange)
+	if !ok {
+		panic(fmt.Sprintf("no valid position for reporting node %v", node))
+	}
+	d := analysis.Diagnostic{
+		Pos:            pos,
+		End:            end,
+		Message:        message,
+		SuggestedFixes: cfg.Fixes,
+		Related:        cfg.Related,
+	}
+	pass.Report(d)
+}
+
+func Render(pass *analysis.Pass, x interface{}) string {
+	var buf bytes.Buffer
+	if err := format.Node(&buf, pass.Fset, x); err != nil {
+		panic(err)
+	}
+	return buf.String()
+}
+
+func RenderArgs(pass *analysis.Pass, args []ast.Expr) string {
+	var ss []string
+	for _, arg := range args {
+		ss = append(ss, Render(pass, arg))
+	}
+	return strings.Join(ss, ", ")
+}
+
+func DisplayPosition(fset *token.FileSet, p token.Pos) token.Position {
+	if p == token.NoPos {
+		return token.Position{}
+	}
+
+	// Only use the adjusted position if it points to another Go file.
+	// This means we'll point to the original file for cgo files, but
+	// we won't point to a YACC grammar file.
+	pos := fset.PositionFor(p, false)
+	adjPos := fset.PositionFor(p, true)
+
+	if filepath.Ext(adjPos.Filename) == ".go" {
+		return adjPos
+	}
+
+	return pos
+}
+
+func Ordinal(n int) string {
+	suffix := "th"
+	if n < 10 || n > 20 {
+		switch n % 10 {
+		case 0:
+			suffix = "th"
+		case 1:
+			suffix = "st"
+		case 2:
+			suffix = "nd"
+		case 3:
+			suffix = "rd"
+		default:
+			suffix = "th"
+		}
+	}
+
+	return strconv.Itoa(n) + suffix
+}

vendor/honnef.co/go/tools/cmd/staticcheck/README.md

@@ -0,0 +1,15 @@
+# staticcheck
+
+_staticcheck_ offers extensive analysis of Go code, covering a myriad
+of categories. It will detect bugs, suggest code simplifications,
+point out dead code, and more.
+
+## Installation
+
+See [the main README](https://github.com/dominikh/go-tools#installation) for installation instructions.
+
+## Documentation
+
+Detailed documentation can be found on
+[staticcheck.io](https://staticcheck.io/docs/).
+

vendor/honnef.co/go/tools/cmd/staticcheck/staticcheck.go

@@ -0,0 +1,45 @@
+// staticcheck analyses Go code and makes it better.
+package main
+
+import (
+	"log"
+	"os"
+
+	"honnef.co/go/tools/lintcmd"
+	"honnef.co/go/tools/lintcmd/version"
+	"honnef.co/go/tools/quickfix"
+	"honnef.co/go/tools/simple"
+	"honnef.co/go/tools/staticcheck"
+	"honnef.co/go/tools/stylecheck"
+	"honnef.co/go/tools/unused"
+)
+
+func main() {
+	cmd := lintcmd.NewCommand("staticcheck")
+	cmd.SetVersion(version.Version, version.MachineVersion)
+
+	fs := cmd.FlagSet()
+	debug := fs.String("debug.unused-graph", "", "Write unused's object graph to `file`")
+	qf := fs.Bool("debug.run-quickfix-analyzers", false, "Run quickfix analyzers")
+
+	cmd.ParseFlags(os.Args[1:])
+
+	cmd.AddAnalyzers(simple.Analyzers...)
+	cmd.AddAnalyzers(staticcheck.Analyzers...)
+	cmd.AddAnalyzers(stylecheck.Analyzers...)
+	cmd.AddAnalyzers(unused.Analyzer)
+
+	if *qf {
+		cmd.AddAnalyzers(quickfix.Analyzers...)
+	}
+
+	if *debug != "" {
+		f, err := os.OpenFile(*debug, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0666)
+		if err != nil {
+			log.Fatal(err)
+		}
+		unused.Debug = f
+	}
+
+	cmd.Run()
+}

vendor/honnef.co/go/tools/config/config.go

@@ -0,0 +1,266 @@
+package config
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/token"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+
+	"github.com/BurntSushi/toml"
+	"golang.org/x/tools/go/analysis"
+)
+
+// Dir looks at a list of absolute file names, which should make up a
+// single package, and returns the path of the directory that may
+// contain a staticcheck.conf file. It returns the empty string if no
+// such directory could be determined, for example because all files
+// were located in Go's build cache.
+func Dir(files []string) string {
+	if len(files) == 0 {
+		return ""
+	}
+	cache, err := os.UserCacheDir()
+	if err != nil {
+		cache = ""
+	}
+	var path string
+	for _, p := range files {
+		// FIXME(dh): using strings.HasPrefix isn't technically
+		// correct, but it should be good enough for now.
+		if cache != "" && strings.HasPrefix(p, cache) {
+			// File in the build cache of the standard Go build system
+			continue
+		}
+		path = p
+		break
+	}
+
+	if path == "" {
+		// The package only consists of generated files.
+		return ""
+	}
+
+	dir := filepath.Dir(path)
+	return dir
+}
+
+func dirAST(files []*ast.File, fset *token.FileSet) string {
+	names := make([]string, len(files))
+	for i, f := range files {
+		names[i] = fset.PositionFor(f.Pos(), true).Filename
+	}
+	return Dir(names)
+}
+
+var Analyzer = &analysis.Analyzer{
+	Name: "config",
+	Doc:  "loads configuration for the current package tree",
+	Run: func(pass *analysis.Pass) (interface{}, error) {
+		dir := dirAST(pass.Files, pass.Fset)
+		if dir == "" {
+			cfg := DefaultConfig
+			return &cfg, nil
+		}
+		cfg, err := Load(dir)
+		if err != nil {
+			return nil, fmt.Errorf("error loading staticcheck.conf: %s", err)
+		}
+		return &cfg, nil
+	},
+	RunDespiteErrors: true,
+	ResultType:       reflect.TypeOf((*Config)(nil)),
+}
+
+func For(pass *analysis.Pass) *Config {
+	return pass.ResultOf[Analyzer].(*Config)
+}
+
+func mergeLists(a, b []string) []string {
+	out := make([]string, 0, len(a)+len(b))
+	for _, el := range b {
+		if el == "inherit" {
+			out = append(out, a...)
+		} else {
+			out = append(out, el)
+		}
+	}
+
+	return out
+}
+
+func normalizeList(list []string) []string {
+	if len(list) > 1 {
+		nlist := make([]string, 0, len(list))
+		nlist = append(nlist, list[0])
+		for i, el := range list[1:] {
+			if el != list[i] {
+				nlist = append(nlist, el)
+			}
+		}
+		list = nlist
+	}
+
+	for _, el := range list {
+		if el == "inherit" {
+			// This should never happen, because the default config
+			// should not use "inherit"
+			panic(`unresolved "inherit"`)
+		}
+	}
+
+	return list
+}
+
+func (cfg Config) Merge(ocfg Config) Config {
+	if ocfg.Checks != nil {
+		cfg.Checks = mergeLists(cfg.Checks, ocfg.Checks)
+	}
+	if ocfg.Initialisms != nil {
+		cfg.Initialisms = mergeLists(cfg.Initialisms, ocfg.Initialisms)
+	}
+	if ocfg.DotImportWhitelist != nil {
+		cfg.DotImportWhitelist = mergeLists(cfg.DotImportWhitelist, ocfg.DotImportWhitelist)
+	}
+	if ocfg.HTTPStatusCodeWhitelist != nil {
+		cfg.HTTPStatusCodeWhitelist = mergeLists(cfg.HTTPStatusCodeWhitelist, ocfg.HTTPStatusCodeWhitelist)
+	}
+	return cfg
+}
+
+type Config struct {
+	// TODO(dh): this implementation makes it impossible for external
+	// clients to add their own checkers with configuration. At the
+	// moment, we don't really care about that; we don't encourage
+	// that people use this package. In the future, we may. The
+	// obvious solution would be using map[string]interface{}, but
+	// that's obviously subpar.
+
+	Checks                  []string `toml:"checks"`
+	Initialisms             []string `toml:"initialisms"`
+	DotImportWhitelist      []string `toml:"dot_import_whitelist"`
+	HTTPStatusCodeWhitelist []string `toml:"http_status_code_whitelist"`
+}
+
+func (c Config) String() string {
+	buf := &bytes.Buffer{}
+
+	fmt.Fprintf(buf, "Checks: %#v\n", c.Checks)
+	fmt.Fprintf(buf, "Initialisms: %#v\n", c.Initialisms)
+	fmt.Fprintf(buf, "DotImportWhitelist: %#v\n", c.DotImportWhitelist)
+	fmt.Fprintf(buf, "HTTPStatusCodeWhitelist: %#v", c.HTTPStatusCodeWhitelist)
+
+	return buf.String()
+}
+
+// DefaultConfig is the default configuration.
+// Its initial value describes the majority of the default configuration,
+// but the Checks field can be updated at runtime based on the analyzers being used, to disable non-default checks.
+// For cmd/staticcheck, this is handled by (*lintcmd.Command).Run.
+//
+// Note that DefaultConfig shouldn't be modified while analyzers are executing.
+var DefaultConfig = Config{
+	Checks: []string{"all"},
+	Initialisms: []string{
+		"ACL", "API", "ASCII", "CPU", "CSS", "DNS",
+		"EOF", "GUID", "HTML", "HTTP", "HTTPS", "ID",
+		"IP", "JSON", "QPS", "RAM", "RPC", "SLA",
+		"SMTP", "SQL", "SSH", "TCP", "TLS", "TTL",
+		"UDP", "UI", "GID", "UID", "UUID", "URI",
+		"URL", "UTF8", "VM", "XML", "XMPP", "XSRF",
+		"XSS", "SIP", "RTP", "AMQP", "DB", "TS",
+	},
+	DotImportWhitelist: []string{
+		"github.com/mmcloughlin/avo/build",
+		"github.com/mmcloughlin/avo/operand",
+		"github.com/mmcloughlin/avo/reg",
+	},
+	HTTPStatusCodeWhitelist: []string{"200", "400", "404", "500"},
+}
+
+const ConfigName = "staticcheck.conf"
+
+type ParseError struct {
+	Filename string
+	toml.ParseError
+}
+
+func parseConfigs(dir string) ([]Config, error) {
+	var out []Config
+
+	// TODO(dh): consider stopping at the GOPATH/module boundary
+	for dir != "" {
+		f, err := os.Open(filepath.Join(dir, ConfigName))
+		if os.IsNotExist(err) {
+			ndir := filepath.Dir(dir)
+			if ndir == dir {
+				break
+			}
+			dir = ndir
+			continue
+		}
+		if err != nil {
+			return nil, err
+		}
+		var cfg Config
+		_, err = toml.DecodeReader(f, &cfg)
+		f.Close()
+		if err != nil {
+			if err, ok := err.(toml.ParseError); ok {
+				return nil, ParseError{
+					Filename:   filepath.Join(dir, ConfigName),
+					ParseError: err,
+				}
+			}
+			return nil, err
+		}
+		out = append(out, cfg)
+		ndir := filepath.Dir(dir)
+		if ndir == dir {
+			break
+		}
+		dir = ndir
+	}
+	out = append(out, DefaultConfig)
+	if len(out) < 2 {
+		return out, nil
+	}
+	for i := 0; i < len(out)/2; i++ {
+		out[i], out[len(out)-1-i] = out[len(out)-1-i], out[i]
+	}
+	return out, nil
+}
+
+func mergeConfigs(confs []Config) Config {
+	if len(confs) == 0 {
+		// This shouldn't happen because we always have at least a
+		// default config.
+		panic("trying to merge zero configs")
+	}
+	if len(confs) == 1 {
+		return confs[0]
+	}
+	conf := confs[0]
+	for _, oconf := range confs[1:] {
+		conf = conf.Merge(oconf)
+	}
+	return conf
+}
+
+func Load(dir string) (Config, error) {
+	confs, err := parseConfigs(dir)
+	if err != nil {
+		return Config{}, err
+	}
+	conf := mergeConfigs(confs)
+
+	conf.Checks = normalizeList(conf.Checks)
+	conf.Initialisms = normalizeList(conf.Initialisms)
+	conf.DotImportWhitelist = normalizeList(conf.DotImportWhitelist)
+	conf.HTTPStatusCodeWhitelist = normalizeList(conf.HTTPStatusCodeWhitelist)
+
+	return conf, nil
+}

vendor/honnef.co/go/tools/config/example.conf

@@ -0,0 +1,14 @@
+checks = ["all", "-ST1000", "-ST1003", "-ST1016", "-ST1020", "-ST1021", "-ST1022", "-ST1023"]
+initialisms = ["ACL", "API", "ASCII", "CPU", "CSS", "DNS",
+	"EOF", "GUID", "HTML", "HTTP", "HTTPS", "ID",
+	"IP", "JSON", "QPS", "RAM", "RPC", "SLA",
+	"SMTP", "SQL", "SSH", "TCP", "TLS", "TTL",
+	"UDP", "UI", "GID", "UID", "UUID", "URI",
+	"URL", "UTF8", "VM", "XML", "XMPP", "XSRF",
+	"XSS", "SIP", "RTP", "AMQP", "DB", "TS"]
+dot_import_whitelist = [
+    "github.com/mmcloughlin/avo/build",
+    "github.com/mmcloughlin/avo/operand",
+    "github.com/mmcloughlin/avo/reg",
+]
+http_status_code_whitelist = ["200", "400", "404", "500"]

vendor/honnef.co/go/tools/go/ast/astutil/upstream.go

@@ -0,0 +1,20 @@
+package astutil
+
+import (
+	"go/ast"
+	"go/token"
+	_ "unsafe"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+type Cursor = astutil.Cursor
+type ApplyFunc = astutil.ApplyFunc
+
+func Apply(root ast.Node, pre, post ApplyFunc) (result ast.Node) {
+	return astutil.Apply(root, pre, post)
+}
+
+func PathEnclosingInterval(root *ast.File, start, end token.Pos) (path []ast.Node, exact bool) {
+	return astutil.PathEnclosingInterval(root, start, end)
+}

vendor/honnef.co/go/tools/go/ast/astutil/util.go

@@ -0,0 +1,364 @@
+package astutil
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"reflect"
+	"strings"
+
+	"golang.org/x/exp/typeparams"
+)
+
+func IsIdent(expr ast.Expr, ident string) bool {
+	id, ok := expr.(*ast.Ident)
+	return ok && id.Name == ident
+}
+
+// isBlank returns whether id is the blank identifier "_".
+// If id == nil, the answer is false.
+func IsBlank(id ast.Expr) bool {
+	ident, _ := id.(*ast.Ident)
+	return ident != nil && ident.Name == "_"
+}
+
+// Deprecated: use code.IsIntegerLiteral instead.
+func IsIntLiteral(expr ast.Expr, literal string) bool {
+	lit, ok := expr.(*ast.BasicLit)
+	return ok && lit.Kind == token.INT && lit.Value == literal
+}
+
+// Deprecated: use IsIntLiteral instead
+func IsZero(expr ast.Expr) bool {
+	return IsIntLiteral(expr, "0")
+}
+
+func Preamble(f *ast.File) string {
+	cutoff := f.Package
+	if f.Doc != nil {
+		cutoff = f.Doc.Pos()
+	}
+	var out []string
+	for _, cmt := range f.Comments {
+		if cmt.Pos() >= cutoff {
+			break
+		}
+		out = append(out, cmt.Text())
+	}
+	return strings.Join(out, "\n")
+}
+
+func GroupSpecs(fset *token.FileSet, specs []ast.Spec) [][]ast.Spec {
+	if len(specs) == 0 {
+		return nil
+	}
+	groups := make([][]ast.Spec, 1)
+	groups[0] = append(groups[0], specs[0])
+
+	for _, spec := range specs[1:] {
+		g := groups[len(groups)-1]
+		if fset.PositionFor(spec.Pos(), false).Line-1 !=
+			fset.PositionFor(g[len(g)-1].End(), false).Line {
+
+			groups = append(groups, nil)
+		}
+
+		groups[len(groups)-1] = append(groups[len(groups)-1], spec)
+	}
+
+	return groups
+}
+
+// Unparen returns e with any enclosing parentheses stripped.
+func Unparen(e ast.Expr) ast.Expr {
+	for {
+		p, ok := e.(*ast.ParenExpr)
+		if !ok {
+			return e
+		}
+		e = p.X
+	}
+}
+
+// CopyExpr creates a deep copy of an expression.
+// It doesn't support copying FuncLits and returns ok == false when encountering one.
+func CopyExpr(node ast.Expr) (ast.Expr, bool) {
+	switch node := node.(type) {
+	case *ast.BasicLit:
+		cp := *node
+		return &cp, true
+	case *ast.BinaryExpr:
+		cp := *node
+		var ok1, ok2 bool
+		cp.X, ok1 = CopyExpr(cp.X)
+		cp.Y, ok2 = CopyExpr(cp.Y)
+		return &cp, ok1 && ok2
+	case *ast.CallExpr:
+		var ok bool
+		cp := *node
+		cp.Fun, ok = CopyExpr(cp.Fun)
+		if !ok {
+			return nil, false
+		}
+		cp.Args = make([]ast.Expr, len(node.Args))
+		for i, v := range node.Args {
+			cp.Args[i], ok = CopyExpr(v)
+			if !ok {
+				return nil, false
+			}
+		}
+		return &cp, true
+	case *ast.CompositeLit:
+		var ok bool
+		cp := *node
+		cp.Type, ok = CopyExpr(cp.Type)
+		if !ok {
+			return nil, false
+		}
+		cp.Elts = make([]ast.Expr, len(node.Elts))
+		for i, v := range node.Elts {
+			cp.Elts[i], ok = CopyExpr(v)
+			if !ok {
+				return nil, false
+			}
+		}
+		return &cp, true
+	case *ast.Ident:
+		cp := *node
+		return &cp, true
+	case *ast.IndexExpr:
+		var ok1, ok2 bool
+		cp := *node
+		cp.X, ok1 = CopyExpr(cp.X)
+		cp.Index, ok2 = CopyExpr(cp.Index)
+		return &cp, ok1 && ok2
+	case *typeparams.IndexListExpr:
+		var ok bool
+		cp := *node
+		cp.X, ok = CopyExpr(cp.X)
+		if !ok {
+			return nil, false
+		}
+		for i, v := range node.Indices {
+			cp.Indices[i], ok = CopyExpr(v)
+			if !ok {
+				return nil, false
+			}
+		}
+		return &cp, true
+	case *ast.KeyValueExpr:
+		var ok1, ok2 bool
+		cp := *node
+		cp.Key, ok1 = CopyExpr(cp.Key)
+		cp.Value, ok2 = CopyExpr(cp.Value)
+		return &cp, ok1 && ok2
+	case *ast.ParenExpr:
+		var ok bool
+		cp := *node
+		cp.X, ok = CopyExpr(cp.X)
+		return &cp, ok
+	case *ast.SelectorExpr:
+		var ok bool
+		cp := *node
+		cp.X, ok = CopyExpr(cp.X)
+		if !ok {
+			return nil, false
+		}
+		sel, ok := CopyExpr(cp.Sel)
+		if !ok {
+			// this is impossible
+			return nil, false
+		}
+		cp.Sel = sel.(*ast.Ident)
+		return &cp, true
+	case *ast.SliceExpr:
+		var ok1, ok2, ok3, ok4 bool
+		cp := *node
+		cp.X, ok1 = CopyExpr(cp.X)
+		cp.Low, ok2 = CopyExpr(cp.Low)
+		cp.High, ok3 = CopyExpr(cp.High)
+		cp.Max, ok4 = CopyExpr(cp.Max)
+		return &cp, ok1 && ok2 && ok3 && ok4
+	case *ast.StarExpr:
+		var ok bool
+		cp := *node
+		cp.X, ok = CopyExpr(cp.X)
+		return &cp, ok
+	case *ast.TypeAssertExpr:
+		var ok1, ok2 bool
+		cp := *node
+		cp.X, ok1 = CopyExpr(cp.X)
+		cp.Type, ok2 = CopyExpr(cp.Type)
+		return &cp, ok1 && ok2
+	case *ast.UnaryExpr:
+		var ok bool
+		cp := *node
+		cp.X, ok = CopyExpr(cp.X)
+		return &cp, ok
+	case *ast.MapType:
+		var ok1, ok2 bool
+		cp := *node
+		cp.Key, ok1 = CopyExpr(cp.Key)
+		cp.Value, ok2 = CopyExpr(cp.Value)
+		return &cp, ok1 && ok2
+	case *ast.ArrayType:
+		var ok1, ok2 bool
+		cp := *node
+		cp.Len, ok1 = CopyExpr(cp.Len)
+		cp.Elt, ok2 = CopyExpr(cp.Elt)
+		return &cp, ok1 && ok2
+	case *ast.Ellipsis:
+		var ok bool
+		cp := *node
+		cp.Elt, ok = CopyExpr(cp.Elt)
+		return &cp, ok
+	case *ast.InterfaceType:
+		cp := *node
+		return &cp, true
+	case *ast.StructType:
+		cp := *node
+		return &cp, true
+	case *ast.FuncLit, *ast.FuncType:
+		// TODO(dh): implement copying of function literals and types.
+		return nil, false
+	case *ast.ChanType:
+		var ok bool
+		cp := *node
+		cp.Value, ok = CopyExpr(cp.Value)
+		return &cp, ok
+	case nil:
+		return nil, true
+	default:
+		panic(fmt.Sprintf("unreachable: %T", node))
+	}
+}
+
+func Equal(a, b ast.Node) bool {
+	if a == b {
+		return true
+	}
+	if a == nil || b == nil {
+		return false
+	}
+	if reflect.TypeOf(a) != reflect.TypeOf(b) {
+		return false
+	}
+
+	switch a := a.(type) {
+	case *ast.BasicLit:
+		b := b.(*ast.BasicLit)
+		return a.Kind == b.Kind && a.Value == b.Value
+	case *ast.BinaryExpr:
+		b := b.(*ast.BinaryExpr)
+		return Equal(a.X, b.X) && a.Op == b.Op && Equal(a.Y, b.Y)
+	case *ast.CallExpr:
+		b := b.(*ast.CallExpr)
+		if len(a.Args) != len(b.Args) {
+			return false
+		}
+		for i, arg := range a.Args {
+			if !Equal(arg, b.Args[i]) {
+				return false
+			}
+		}
+		return Equal(a.Fun, b.Fun) &&
+			(a.Ellipsis == token.NoPos && b.Ellipsis == token.NoPos || a.Ellipsis != token.NoPos && b.Ellipsis != token.NoPos)
+	case *ast.CompositeLit:
+		b := b.(*ast.CompositeLit)
+		if len(a.Elts) != len(b.Elts) {
+			return false
+		}
+		for i, elt := range b.Elts {
+			if !Equal(elt, b.Elts[i]) {
+				return false
+			}
+		}
+		return Equal(a.Type, b.Type) && a.Incomplete == b.Incomplete
+	case *ast.Ident:
+		b := b.(*ast.Ident)
+		return a.Name == b.Name
+	case *ast.IndexExpr:
+		b := b.(*ast.IndexExpr)
+		return Equal(a.X, b.X) && Equal(a.Index, b.Index)
+	case *typeparams.IndexListExpr:
+		b := b.(*typeparams.IndexListExpr)
+		if len(a.Indices) != len(b.Indices) {
+			return false
+		}
+		for i, v := range a.Indices {
+			if !Equal(v, b.Indices[i]) {
+				return false
+			}
+		}
+		return Equal(a.X, b.X)
+	case *ast.KeyValueExpr:
+		b := b.(*ast.KeyValueExpr)
+		return Equal(a.Key, b.Key) && Equal(a.Value, b.Value)
+	case *ast.ParenExpr:
+		b := b.(*ast.ParenExpr)
+		return Equal(a.X, b.X)
+	case *ast.SelectorExpr:
+		b := b.(*ast.SelectorExpr)
+		return Equal(a.X, b.X) && Equal(a.Sel, b.Sel)
+	case *ast.SliceExpr:
+		b := b.(*ast.SliceExpr)
+		return Equal(a.X, b.X) && Equal(a.Low, b.Low) && Equal(a.High, b.High) && Equal(a.Max, b.Max) && a.Slice3 == b.Slice3
+	case *ast.StarExpr:
+		b := b.(*ast.StarExpr)
+		return Equal(a.X, b.X)
+	case *ast.TypeAssertExpr:
+		b := b.(*ast.TypeAssertExpr)
+		return Equal(a.X, b.X) && Equal(a.Type, b.Type)
+	case *ast.UnaryExpr:
+		b := b.(*ast.UnaryExpr)
+		return a.Op == b.Op && Equal(a.X, b.X)
+	case *ast.MapType:
+		b := b.(*ast.MapType)
+		return Equal(a.Key, b.Key) && Equal(a.Value, b.Value)
+	case *ast.ArrayType:
+		b := b.(*ast.ArrayType)
+		return Equal(a.Len, b.Len) && Equal(a.Elt, b.Elt)
+	case *ast.Ellipsis:
+		b := b.(*ast.Ellipsis)
+		return Equal(a.Elt, b.Elt)
+	case *ast.InterfaceType:
+		b := b.(*ast.InterfaceType)
+		return a.Incomplete == b.Incomplete && Equal(a.Methods, b.Methods)
+	case *ast.StructType:
+		b := b.(*ast.StructType)
+		return a.Incomplete == b.Incomplete && Equal(a.Fields, b.Fields)
+	case *ast.FuncLit:
+		// TODO(dh): support function literals
+		return false
+	case *ast.ChanType:
+		b := b.(*ast.ChanType)
+		return a.Dir == b.Dir && (a.Arrow == token.NoPos && b.Arrow == token.NoPos || a.Arrow != token.NoPos && b.Arrow != token.NoPos)
+	case *ast.FieldList:
+		b := b.(*ast.FieldList)
+		if len(a.List) != len(b.List) {
+			return false
+		}
+		for i, fieldA := range a.List {
+			if !Equal(fieldA, b.List[i]) {
+				return false
+			}
+		}
+		return true
+	case *ast.Field:
+		b := b.(*ast.Field)
+		if len(a.Names) != len(b.Names) {
+			return false
+		}
+		for j, name := range a.Names {
+			if !Equal(name, b.Names[j]) {
+				return false
+			}
+		}
+		if !Equal(a.Type, b.Type) || !Equal(a.Tag, b.Tag) {
+			return false
+		}
+		return true
+	default:
+		panic(fmt.Sprintf("unreachable: %T", a))
+	}
+}

vendor/honnef.co/go/tools/go/buildid/UPSTREAM

@@ -0,0 +1,5 @@
+This package extracts buildid.go and note.go from cmd/internal/buildid/.
+
+We have modified it to remove support for AIX big archive files, to cut down on our dependencies.
+
+The last upstream commit we've looked at was: 639acdc833bfd12b7edd43092d1b380d70cb2874

vendor/honnef.co/go/tools/go/buildid/buildid.go

@@ -0,0 +1,238 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package buildid
+
+import (
+	"bytes"
+	"debug/elf"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+var errBuildIDMalformed = fmt.Errorf("malformed object file")
+
+var (
+	bangArch = []byte("!<arch>")
+	pkgdef   = []byte("__.PKGDEF")
+	goobject = []byte("go object ")
+	buildid  = []byte("build id ")
+)
+
+// ReadFile reads the build ID from an archive or executable file.
+func ReadFile(name string) (id string, err error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	buf := make([]byte, 8)
+	if _, err := f.ReadAt(buf, 0); err != nil {
+		return "", err
+	}
+	if string(buf) != "!<arch>\n" {
+		if string(buf) == "<bigaf>\n" {
+			return "", errors.New("unsupported")
+		}
+		return readBinary(name, f)
+	}
+
+	// Read just enough of the target to fetch the build ID.
+	// The archive is expected to look like:
+	//
+	//	!<arch>
+	//	__.PKGDEF       0           0     0     644     7955      `
+	//	go object darwin amd64 devel X:none
+	//	build id "b41e5c45250e25c9fd5e9f9a1de7857ea0d41224"
+	//
+	// The variable-sized strings are GOOS, GOARCH, and the experiment list (X:none).
+	// Reading the first 1024 bytes should be plenty.
+	data := make([]byte, 1024)
+	n, err := io.ReadFull(f, data)
+	if err != nil && n == 0 {
+		return "", err
+	}
+
+	tryGccgo := func() (string, error) {
+		return readGccgoArchive(name, f)
+	}
+
+	// Archive header.
+	for i := 0; ; i++ { // returns during i==3
+		j := bytes.IndexByte(data, '\n')
+		if j < 0 {
+			return tryGccgo()
+		}
+		line := data[:j]
+		data = data[j+1:]
+		switch i {
+		case 0:
+			if !bytes.Equal(line, bangArch) {
+				return tryGccgo()
+			}
+		case 1:
+			if !bytes.HasPrefix(line, pkgdef) {
+				return tryGccgo()
+			}
+		case 2:
+			if !bytes.HasPrefix(line, goobject) {
+				return tryGccgo()
+			}
+		case 3:
+			if !bytes.HasPrefix(line, buildid) {
+				// Found the object header, just doesn't have a build id line.
+				// Treat as successful, with empty build id.
+				return "", nil
+			}
+			id, err := strconv.Unquote(string(line[len(buildid):]))
+			if err != nil {
+				return tryGccgo()
+			}
+			return id, nil
+		}
+	}
+}
+
+// readGccgoArchive tries to parse the archive as a standard Unix
+// archive file, and fetch the build ID from the _buildid.o entry.
+// The _buildid.o entry is written by (*Builder).gccgoBuildIDELFFile
+// in cmd/go/internal/work/exec.go.
+func readGccgoArchive(name string, f *os.File) (string, error) {
+	bad := func() (string, error) {
+		return "", &os.PathError{Op: "parse", Path: name, Err: errBuildIDMalformed}
+	}
+
+	off := int64(8)
+	for {
+		if _, err := f.Seek(off, io.SeekStart); err != nil {
+			return "", err
+		}
+
+		// TODO(iant): Make a debug/ar package, and use it
+		// here and in cmd/link.
+		var hdr [60]byte
+		if _, err := io.ReadFull(f, hdr[:]); err != nil {
+			if err == io.EOF {
+				// No more entries, no build ID.
+				return "", nil
+			}
+			return "", err
+		}
+		off += 60
+
+		sizeStr := strings.TrimSpace(string(hdr[48:58]))
+		size, err := strconv.ParseInt(sizeStr, 0, 64)
+		if err != nil {
+			return bad()
+		}
+
+		name := strings.TrimSpace(string(hdr[:16]))
+		if name == "_buildid.o/" {
+			sr := io.NewSectionReader(f, off, size)
+			e, err := elf.NewFile(sr)
+			if err != nil {
+				return bad()
+			}
+			s := e.Section(".go.buildid")
+			if s == nil {
+				return bad()
+			}
+			data, err := s.Data()
+			if err != nil {
+				return bad()
+			}
+			return string(data), nil
+		}
+
+		off += size
+		if off&1 != 0 {
+			off++
+		}
+	}
+}
+
+var (
+	goBuildPrefix = []byte("\xff Go build ID: \"")
+	goBuildEnd    = []byte("\"\n \xff")
+
+	elfPrefix = []byte("\x7fELF")
+
+	machoPrefixes = [][]byte{
+		{0xfe, 0xed, 0xfa, 0xce},
+		{0xfe, 0xed, 0xfa, 0xcf},
+		{0xce, 0xfa, 0xed, 0xfe},
+		{0xcf, 0xfa, 0xed, 0xfe},
+	}
+)
+
+var readSize = 32 * 1024 // changed for testing
+
+// readBinary reads the build ID from a binary.
+//
+// ELF binaries store the build ID in a proper PT_NOTE section.
+//
+// Other binary formats are not so flexible. For those, the linker
+// stores the build ID as non-instruction bytes at the very beginning
+// of the text segment, which should appear near the beginning
+// of the file. This is clumsy but fairly portable. Custom locations
+// can be added for other binary types as needed, like we did for ELF.
+func readBinary(name string, f *os.File) (id string, err error) {
+	// Read the first 32 kB of the binary file.
+	// That should be enough to find the build ID.
+	// In ELF files, the build ID is in the leading headers,
+	// which are typically less than 4 kB, not to mention 32 kB.
+	// In Mach-O files, there's no limit, so we have to parse the file.
+	// On other systems, we're trying to read enough that
+	// we get the beginning of the text segment in the read.
+	// The offset where the text segment begins in a hello
+	// world compiled for each different object format today:
+	//
+	//	Plan 9: 0x20
+	//	Windows: 0x600
+	//
+	data := make([]byte, readSize)
+	_, err = io.ReadFull(f, data)
+	if err == io.ErrUnexpectedEOF {
+		err = nil
+	}
+	if err != nil {
+		return "", err
+	}
+
+	if bytes.HasPrefix(data, elfPrefix) {
+		return readELF(name, f, data)
+	}
+	for _, m := range machoPrefixes {
+		if bytes.HasPrefix(data, m) {
+			return readMacho(name, f, data)
+		}
+	}
+	return readRaw(name, data)
+}
+
+// readRaw finds the raw build ID stored in text segment data.
+func readRaw(name string, data []byte) (id string, err error) {
+	i := bytes.Index(data, goBuildPrefix)
+	if i < 0 {
+		// Missing. Treat as successful but build ID empty.
+		return "", nil
+	}
+
+	j := bytes.Index(data[i+len(goBuildPrefix):], goBuildEnd)
+	if j < 0 {
+		return "", &os.PathError{Op: "parse", Path: name, Err: errBuildIDMalformed}
+	}
+
+	quoted := data[i+len(goBuildPrefix)-1 : i+len(goBuildPrefix)+j+1]
+	id, err = strconv.Unquote(string(quoted))
+	if err != nil {
+		return "", &os.PathError{Op: "parse", Path: name, Err: errBuildIDMalformed}
+	}
+	return id, nil
+}

vendor/honnef.co/go/tools/go/buildid/note.go

@@ -0,0 +1,207 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package buildid
+
+import (
+	"bytes"
+	"debug/elf"
+	"debug/macho"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"os"
+)
+
+func readAligned4(r io.Reader, sz int32) ([]byte, error) {
+	full := (sz + 3) &^ 3
+	data := make([]byte, full)
+	_, err := io.ReadFull(r, data)
+	if err != nil {
+		return nil, err
+	}
+	data = data[:sz]
+	return data, nil
+}
+
+func ReadELFNote(filename, name string, typ int32) ([]byte, error) {
+	f, err := elf.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	for _, sect := range f.Sections {
+		if sect.Type != elf.SHT_NOTE {
+			continue
+		}
+		r := sect.Open()
+		for {
+			var namesize, descsize, noteType int32
+			err = binary.Read(r, f.ByteOrder, &namesize)
+			if err != nil {
+				if err == io.EOF {
+					break
+				}
+				return nil, fmt.Errorf("read namesize failed: %v", err)
+			}
+			err = binary.Read(r, f.ByteOrder, &descsize)
+			if err != nil {
+				return nil, fmt.Errorf("read descsize failed: %v", err)
+			}
+			err = binary.Read(r, f.ByteOrder, &noteType)
+			if err != nil {
+				return nil, fmt.Errorf("read type failed: %v", err)
+			}
+			noteName, err := readAligned4(r, namesize)
+			if err != nil {
+				return nil, fmt.Errorf("read name failed: %v", err)
+			}
+			desc, err := readAligned4(r, descsize)
+			if err != nil {
+				return nil, fmt.Errorf("read desc failed: %v", err)
+			}
+			if name == string(noteName) && typ == noteType {
+				return desc, nil
+			}
+		}
+	}
+	return nil, nil
+}
+
+var elfGoNote = []byte("Go\x00\x00")
+var elfGNUNote = []byte("GNU\x00")
+
+// The Go build ID is stored in a note described by an ELF PT_NOTE prog
+// header. The caller has already opened filename, to get f, and read
+// at least 4 kB out, in data.
+func readELF(name string, f *os.File, data []byte) (buildid string, err error) {
+	// Assume the note content is in the data, already read.
+	// Rewrite the ELF header to set shnum to 0, so that we can pass
+	// the data to elf.NewFile and it will decode the Prog list but not
+	// try to read the section headers and the string table from disk.
+	// That's a waste of I/O when all we care about is the Prog list
+	// and the one ELF note.
+	switch elf.Class(data[elf.EI_CLASS]) {
+	case elf.ELFCLASS32:
+		data[48] = 0
+		data[49] = 0
+	case elf.ELFCLASS64:
+		data[60] = 0
+		data[61] = 0
+	}
+
+	const elfGoBuildIDTag = 4
+	const gnuBuildIDTag = 3
+
+	ef, err := elf.NewFile(bytes.NewReader(data))
+	if err != nil {
+		return "", &os.PathError{Path: name, Op: "parse", Err: err}
+	}
+	var gnu string
+	for _, p := range ef.Progs {
+		if p.Type != elf.PT_NOTE || p.Filesz < 16 {
+			continue
+		}
+
+		var note []byte
+		if p.Off+p.Filesz < uint64(len(data)) {
+			note = data[p.Off : p.Off+p.Filesz]
+		} else {
+			// For some linkers, such as the Solaris linker,
+			// the buildid may not be found in data (which
+			// likely contains the first 16kB of the file)
+			// or even the first few megabytes of the file
+			// due to differences in note segment placement;
+			// in that case, extract the note data manually.
+			_, err = f.Seek(int64(p.Off), io.SeekStart)
+			if err != nil {
+				return "", err
+			}
+
+			note = make([]byte, p.Filesz)
+			_, err = io.ReadFull(f, note)
+			if err != nil {
+				return "", err
+			}
+		}
+
+		filesz := p.Filesz
+		off := p.Off
+		for filesz >= 16 {
+			nameSize := ef.ByteOrder.Uint32(note)
+			valSize := ef.ByteOrder.Uint32(note[4:])
+			tag := ef.ByteOrder.Uint32(note[8:])
+			nname := note[12:16]
+			if nameSize == 4 && 16+valSize <= uint32(len(note)) && tag == elfGoBuildIDTag && bytes.Equal(nname, elfGoNote) {
+				return string(note[16 : 16+valSize]), nil
+			}
+
+			if nameSize == 4 && 16+valSize <= uint32(len(note)) && tag == gnuBuildIDTag && bytes.Equal(nname, elfGNUNote) {
+				gnu = string(note[16 : 16+valSize])
+			}
+
+			nameSize = (nameSize + 3) &^ 3
+			valSize = (valSize + 3) &^ 3
+			notesz := uint64(12 + nameSize + valSize)
+			if filesz <= notesz {
+				break
+			}
+			off += notesz
+			align := p.Align
+			alignedOff := (off + align - 1) &^ (align - 1)
+			notesz += alignedOff - off
+			off = alignedOff
+			filesz -= notesz
+			note = note[notesz:]
+		}
+	}
+
+	// If we didn't find a Go note, use a GNU note if available.
+	// This is what gccgo uses.
+	if gnu != "" {
+		return gnu, nil
+	}
+
+	// No note. Treat as successful but build ID empty.
+	return "", nil
+}
+
+// The Go build ID is stored at the beginning of the Mach-O __text segment.
+// The caller has already opened filename, to get f, and read a few kB out, in data.
+// Sadly, that's not guaranteed to hold the note, because there is an arbitrary amount
+// of other junk placed in the file ahead of the main text.
+func readMacho(name string, f *os.File, data []byte) (buildid string, err error) {
+	// If the data we want has already been read, don't worry about Mach-O parsing.
+	// This is both an optimization and a hedge against the Mach-O parsing failing
+	// in the future due to, for example, the name of the __text section changing.
+	if b, err := readRaw(name, data); b != "" && err == nil {
+		return b, err
+	}
+
+	mf, err := macho.NewFile(f)
+	if err != nil {
+		return "", &os.PathError{Path: name, Op: "parse", Err: err}
+	}
+
+	sect := mf.Section("__text")
+	if sect == nil {
+		// Every binary has a __text section. Something is wrong.
+		return "", &os.PathError{Path: name, Op: "parse", Err: fmt.Errorf("cannot find __text section")}
+	}
+
+	// It should be in the first few bytes, but read a lot just in case,
+	// especially given our past problems on OS X with the build ID moving.
+	// There shouldn't be much difference between reading 4kB and 32kB:
+	// the hard part is getting to the data, not transferring it.
+	n := sect.Size
+	if n > uint64(readSize) {
+		n = uint64(readSize)
+	}
+	buf := make([]byte, n)
+	if _, err := f.ReadAt(buf, int64(sect.Offset)); err != nil {
+		return "", err
+	}
+
+	return readRaw(name, buf)
+}

vendor/honnef.co/go/tools/go/ir/LICENSE

@@ -0,0 +1,28 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+Copyright (c) 2016 Dominik Honnef. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/honnef.co/go/tools/go/ir/UPSTREAM

@@ -0,0 +1,9 @@
+This package started as a copy of golang.org/x/tools/go/ssa, imported from an unknown commit in 2016.
+It has since been heavily modified to match our own needs in an IR.
+The changes are too many to list here, and it is best to consider this package independent of go/ssa.
+
+Upstream changes still get applied when they address bugs in portions of code we have inherited.
+
+The last upstream commit we've looked at was:
+915f6209478fe61eb90dbe155a8a1c58655b931f
+

vendor/honnef.co/go/tools/go/ir/blockopt.go

@@ -0,0 +1,209 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// Simple block optimizations to simplify the control flow graph.
+
+// TODO(adonovan): opt: instead of creating several "unreachable" blocks
+// per function in the Builder, reuse a single one (e.g. at Blocks[1])
+// to reduce garbage.
+
+import (
+	"fmt"
+	"os"
+)
+
+// If true, perform sanity checking and show progress at each
+// successive iteration of optimizeBlocks.  Very verbose.
+const debugBlockOpt = false
+
+// markReachable sets Index=-1 for all blocks reachable from b.
+func markReachable(b *BasicBlock) {
+	b.gaps = -1
+	for _, succ := range b.Succs {
+		if succ.gaps == 0 {
+			markReachable(succ)
+		}
+	}
+}
+
+// deleteUnreachableBlocks marks all reachable blocks of f and
+// eliminates (nils) all others, including possibly cyclic subgraphs.
+//
+func deleteUnreachableBlocks(f *Function) {
+	const white, black = 0, -1
+	// We borrow b.gaps temporarily as the mark bit.
+	for _, b := range f.Blocks {
+		b.gaps = white
+	}
+	markReachable(f.Blocks[0])
+	// In SSI form, we need the exit to be reachable for correct
+	// post-dominance information. In original form, however, we
+	// cannot unconditionally mark it reachable because we won't
+	// be adding fake edges, and this breaks the calculation of
+	// dominance information.
+	markReachable(f.Exit)
+	for i, b := range f.Blocks {
+		if b.gaps == white {
+			for _, c := range b.Succs {
+				if c.gaps == black {
+					c.removePred(b) // delete white->black edge
+				}
+			}
+			if debugBlockOpt {
+				fmt.Fprintln(os.Stderr, "unreachable", b)
+			}
+			f.Blocks[i] = nil // delete b
+		}
+	}
+	f.removeNilBlocks()
+}
+
+// jumpThreading attempts to apply simple jump-threading to block b,
+// in which a->b->c become a->c if b is just a Jump.
+// The result is true if the optimization was applied.
+//
+func jumpThreading(f *Function, b *BasicBlock) bool {
+	if b.Index == 0 {
+		return false // don't apply to entry block
+	}
+	if b.Instrs == nil {
+		return false
+	}
+	for _, pred := range b.Preds {
+		switch pred.Control().(type) {
+		case *ConstantSwitch:
+			// don't optimize away the head blocks of switch statements
+			return false
+		}
+	}
+	if _, ok := b.Instrs[0].(*Jump); !ok {
+		return false // not just a jump
+	}
+	c := b.Succs[0]
+	if c == b {
+		return false // don't apply to degenerate jump-to-self.
+	}
+	if c.hasPhi() {
+		return false // not sound without more effort
+	}
+	for j, a := range b.Preds {
+		a.replaceSucc(b, c)
+
+		// If a now has two edges to c, replace its degenerate If by Jump.
+		if len(a.Succs) == 2 && a.Succs[0] == c && a.Succs[1] == c {
+			jump := new(Jump)
+			jump.setBlock(a)
+			a.Instrs[len(a.Instrs)-1] = jump
+			a.Succs = a.Succs[:1]
+			c.removePred(b)
+		} else {
+			if j == 0 {
+				c.replacePred(b, a)
+			} else {
+				c.Preds = append(c.Preds, a)
+			}
+		}
+
+		if debugBlockOpt {
+			fmt.Fprintln(os.Stderr, "jumpThreading", a, b, c)
+		}
+	}
+	f.Blocks[b.Index] = nil // delete b
+	return true
+}
+
+// fuseBlocks attempts to apply the block fusion optimization to block
+// a, in which a->b becomes ab if len(a.Succs)==len(b.Preds)==1.
+// The result is true if the optimization was applied.
+//
+func fuseBlocks(f *Function, a *BasicBlock) bool {
+	if len(a.Succs) != 1 {
+		return false
+	}
+	if a.Succs[0] == f.Exit {
+		return false
+	}
+	b := a.Succs[0]
+	if len(b.Preds) != 1 {
+		return false
+	}
+	if _, ok := a.Instrs[len(a.Instrs)-1].(*Panic); ok {
+		// panics aren't simple jumps, they have side effects.
+		return false
+	}
+
+	// Degenerate &&/|| ops may result in a straight-line CFG
+	// containing φ-nodes. (Ideally we'd replace such them with
+	// their sole operand but that requires Referrers, built later.)
+	if b.hasPhi() {
+		return false // not sound without further effort
+	}
+
+	// Eliminate jump at end of A, then copy all of B across.
+	a.Instrs = append(a.Instrs[:len(a.Instrs)-1], b.Instrs...)
+	for _, instr := range b.Instrs {
+		instr.setBlock(a)
+	}
+
+	// A inherits B's successors
+	a.Succs = append(a.succs2[:0], b.Succs...)
+
+	// Fix up Preds links of all successors of B.
+	for _, c := range b.Succs {
+		c.replacePred(b, a)
+	}
+
+	if debugBlockOpt {
+		fmt.Fprintln(os.Stderr, "fuseBlocks", a, b)
+	}
+
+	f.Blocks[b.Index] = nil // delete b
+	return true
+}
+
+// optimizeBlocks() performs some simple block optimizations on a
+// completed function: dead block elimination, block fusion, jump
+// threading.
+//
+func optimizeBlocks(f *Function) {
+	if debugBlockOpt {
+		f.WriteTo(os.Stderr)
+		mustSanityCheck(f, nil)
+	}
+
+	deleteUnreachableBlocks(f)
+
+	// Loop until no further progress.
+	changed := true
+	for changed {
+		changed = false
+
+		if debugBlockOpt {
+			f.WriteTo(os.Stderr)
+			mustSanityCheck(f, nil)
+		}
+
+		for _, b := range f.Blocks {
+			// f.Blocks will temporarily contain nils to indicate
+			// deleted blocks; we remove them at the end.
+			if b == nil {
+				continue
+			}
+
+			// Fuse blocks.  b->c becomes bc.
+			if fuseBlocks(f, b) {
+				changed = true
+			}
+
+			// a->b->c becomes a->c if b contains only a Jump.
+			if jumpThreading(f, b) {
+				changed = true
+				continue // (b was disconnected)
+			}
+		}
+	}
+	f.removeNilBlocks()
+}

vendor/honnef.co/go/tools/go/ir/const.go

@@ -0,0 +1,275 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines the Const SSA value type.
+
+import (
+	"fmt"
+	"go/constant"
+	"go/types"
+	"strconv"
+	"strings"
+
+	"golang.org/x/exp/typeparams"
+	"honnef.co/go/tools/go/types/typeutil"
+)
+
+// NewConst returns a new constant of the specified value and type.
+// val must be valid according to the specification of Const.Value.
+//
+func NewConst(val constant.Value, typ types.Type) *Const {
+	return &Const{
+		register: register{
+			typ: typ,
+		},
+		Value: val,
+	}
+}
+
+// intConst returns an 'int' constant that evaluates to i.
+// (i is an int64 in case the host is narrower than the target.)
+func intConst(i int64) *Const {
+	return NewConst(constant.MakeInt64(i), tInt)
+}
+
+// nilConst returns a nil constant of the specified type, which may
+// be any reference type, including interfaces.
+//
+func nilConst(typ types.Type) *Const {
+	return NewConst(nil, typ)
+}
+
+// stringConst returns a 'string' constant that evaluates to s.
+func stringConst(s string) *Const {
+	return NewConst(constant.MakeString(s), tString)
+}
+
+// zeroConst returns a new "zero" constant of the specified type.
+func zeroConst(t types.Type) Constant {
+	if _, ok := t.Underlying().(*types.Interface); ok && !typeparams.IsTypeParam(t) {
+		// Handle non-generic interface early to simplify following code.
+		return nilConst(t)
+	}
+
+	tset := typeutil.NewTypeSet(t)
+
+	switch typ := tset.CoreType().(type) {
+	case *types.Struct:
+		values := make([]Constant, typ.NumFields())
+		for i := 0; i < typ.NumFields(); i++ {
+			values[i] = zeroConst(typ.Field(i).Type())
+		}
+		return &AggregateConst{
+			register: register{typ: t},
+			Values:   values,
+		}
+	case *types.Tuple:
+		values := make([]Constant, typ.Len())
+		for i := 0; i < typ.Len(); i++ {
+			values[i] = zeroConst(typ.At(i).Type())
+		}
+		return &AggregateConst{
+			register: register{typ: t},
+			Values:   values,
+		}
+	}
+
+	isNillable := func(term *typeparams.Term) bool {
+		switch typ := term.Type().Underlying().(type) {
+		case *types.Pointer, *types.Slice, *types.Interface, *types.Chan, *types.Map, *types.Signature, *typeutil.Iterator:
+			return true
+		case *types.Basic:
+			switch typ.Kind() {
+			case types.UnsafePointer, types.UntypedNil:
+				return true
+			default:
+				return false
+			}
+		default:
+			return false
+		}
+	}
+
+	isInfo := func(info types.BasicInfo) func(*typeparams.Term) bool {
+		return func(term *typeparams.Term) bool {
+			basic, ok := term.Type().Underlying().(*types.Basic)
+			if !ok {
+				return false
+			}
+			return (basic.Info() & info) != 0
+		}
+	}
+
+	isArray := func(term *typeparams.Term) bool {
+		_, ok := term.Type().Underlying().(*types.Array)
+		return ok
+	}
+
+	switch {
+	case tset.All(isInfo(types.IsNumeric)):
+		return NewConst(constant.MakeInt64(0), t)
+	case tset.All(isInfo(types.IsString)):
+		return NewConst(constant.MakeString(""), t)
+	case tset.All(isInfo(types.IsBoolean)):
+		return NewConst(constant.MakeBool(false), t)
+	case tset.All(isNillable):
+		return nilConst(t)
+	case tset.All(isArray):
+		var k ArrayConst
+		k.setType(t)
+		return &k
+	default:
+		var k GenericConst
+		k.setType(t)
+		return &k
+	}
+}
+
+func (c *Const) RelString(from *types.Package) string {
+	var p string
+	if c.Value == nil {
+		p = "nil"
+	} else if c.Value.Kind() == constant.String {
+		v := constant.StringVal(c.Value)
+		const max = 20
+		// TODO(adonovan): don't cut a rune in half.
+		if len(v) > max {
+			v = v[:max-3] + "..." // abbreviate
+		}
+		p = strconv.Quote(v)
+	} else {
+		p = c.Value.String()
+	}
+	return fmt.Sprintf("Const <%s> {%s}", relType(c.Type(), from), p)
+}
+
+func (c *Const) String() string {
+	return c.RelString(c.Parent().pkg())
+}
+
+func (v *ArrayConst) RelString(pkg *types.Package) string {
+	return fmt.Sprintf("ArrayConst <%s>", relType(v.Type(), pkg))
+}
+
+func (v *ArrayConst) String() string {
+	return v.RelString(v.Parent().pkg())
+}
+
+func (v *AggregateConst) RelString(pkg *types.Package) string {
+	values := make([]string, len(v.Values))
+	for i, v := range v.Values {
+		if v != nil {
+			values[i] = v.RelString(pkg)
+		} else {
+			values[i] = "nil"
+		}
+	}
+	return fmt.Sprintf("AggregateConst <%s> (%s)", relType(v.Type(), pkg), strings.Join(values, ", "))
+}
+
+func (v *GenericConst) RelString(pkg *types.Package) string {
+	return fmt.Sprintf("GenericConst <%s>", relType(v.Type(), pkg))
+}
+
+func (v *GenericConst) String() string {
+	return v.RelString(v.Parent().pkg())
+}
+
+func (v *AggregateConst) String() string {
+	return v.RelString(v.Parent().pkg())
+}
+
+// IsNil returns true if this constant represents a typed or untyped nil value.
+func (c *Const) IsNil() bool {
+	return c.Value == nil
+}
+
+// Int64 returns the numeric value of this constant truncated to fit
+// a signed 64-bit integer.
+//
+func (c *Const) Int64() int64 {
+	switch x := constant.ToInt(c.Value); x.Kind() {
+	case constant.Int:
+		if i, ok := constant.Int64Val(x); ok {
+			return i
+		}
+		return 0
+	case constant.Float:
+		f, _ := constant.Float64Val(x)
+		return int64(f)
+	}
+	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
+}
+
+// Uint64 returns the numeric value of this constant truncated to fit
+// an unsigned 64-bit integer.
+//
+func (c *Const) Uint64() uint64 {
+	switch x := constant.ToInt(c.Value); x.Kind() {
+	case constant.Int:
+		if u, ok := constant.Uint64Val(x); ok {
+			return u
+		}
+		return 0
+	case constant.Float:
+		f, _ := constant.Float64Val(x)
+		return uint64(f)
+	}
+	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
+}
+
+// Float64 returns the numeric value of this constant truncated to fit
+// a float64.
+//
+func (c *Const) Float64() float64 {
+	f, _ := constant.Float64Val(c.Value)
+	return f
+}
+
+// Complex128 returns the complex value of this constant truncated to
+// fit a complex128.
+//
+func (c *Const) Complex128() complex128 {
+	re, _ := constant.Float64Val(constant.Real(c.Value))
+	im, _ := constant.Float64Val(constant.Imag(c.Value))
+	return complex(re, im)
+}
+
+func (c *Const) equal(o Constant) bool {
+	// TODO(dh): don't use == for types, this will miss identical pointer types, among others
+	oc, ok := o.(*Const)
+	if !ok {
+		return false
+	}
+	return c.typ == oc.typ && c.Value == oc.Value
+}
+
+func (c *AggregateConst) equal(o Constant) bool {
+	oc, ok := o.(*AggregateConst)
+	if !ok {
+		return false
+	}
+	// TODO(dh): don't use == for types, this will miss identical pointer types, among others
+	return c.typ == oc.typ
+}
+
+func (c *ArrayConst) equal(o Constant) bool {
+	oc, ok := o.(*ArrayConst)
+	if !ok {
+		return false
+	}
+	// TODO(dh): don't use == for types, this will miss identical pointer types, among others
+	return c.typ == oc.typ
+}
+
+func (c *GenericConst) equal(o Constant) bool {
+	oc, ok := o.(*GenericConst)
+	if !ok {
+		return false
+	}
+	// TODO(dh): don't use == for types, this will miss identical pointer types, among others
+	return c.typ == oc.typ
+}

vendor/honnef.co/go/tools/go/ir/create.go

@@ -0,0 +1,288 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file implements the CREATE phase of IR construction.
+// See builder.go for explanation.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"os"
+	"sync"
+
+	"honnef.co/go/tools/go/types/typeutil"
+)
+
+// measured on the standard library and rounded up to powers of two,
+// on average there are 8 blocks and 16 instructions per block in a
+// function.
+const avgBlocks = 8
+const avgInstructionsPerBlock = 16
+
+// NewProgram returns a new IR Program.
+//
+// mode controls diagnostics and checking during IR construction.
+//
+func NewProgram(fset *token.FileSet, mode BuilderMode) *Program {
+	prog := &Program{
+		Fset:     fset,
+		imported: make(map[string]*Package),
+		packages: make(map[*types.Package]*Package),
+		thunks:   make(map[selectionKey]*Function),
+		bounds:   make(map[*types.Func]*Function),
+		mode:     mode,
+	}
+
+	h := typeutil.MakeHasher() // protected by methodsMu, in effect
+	prog.methodSets.SetHasher(h)
+	prog.canon.SetHasher(h)
+
+	return prog
+}
+
+// memberFromObject populates package pkg with a member for the
+// typechecker object obj.
+//
+// For objects from Go source code, syntax is the associated syntax
+// tree (for funcs and vars only); it will be used during the build
+// phase.
+//
+func memberFromObject(pkg *Package, obj types.Object, syntax ast.Node) {
+	name := obj.Name()
+	switch obj := obj.(type) {
+	case *types.Builtin:
+		if pkg.Pkg != types.Unsafe {
+			panic("unexpected builtin object: " + obj.String())
+		}
+
+	case *types.TypeName:
+		pkg.Members[name] = &Type{
+			object: obj,
+			pkg:    pkg,
+		}
+
+	case *types.Const:
+		c := &NamedConst{
+			object: obj,
+			Value:  NewConst(obj.Val(), obj.Type()),
+			pkg:    pkg,
+		}
+		pkg.values[obj] = c.Value
+		pkg.Members[name] = c
+
+	case *types.Var:
+		g := &Global{
+			Pkg:    pkg,
+			name:   name,
+			object: obj,
+			typ:    types.NewPointer(obj.Type()), // address
+		}
+		pkg.values[obj] = g
+		pkg.Members[name] = g
+
+	case *types.Func:
+		sig := obj.Type().(*types.Signature)
+		if sig.Recv() == nil && name == "init" {
+			pkg.ninit++
+			name = fmt.Sprintf("init#%d", pkg.ninit)
+		}
+		fn := &Function{
+			name:      name,
+			object:    obj,
+			Signature: sig,
+			Pkg:       pkg,
+			Prog:      pkg.Prog,
+		}
+
+		fn.source = syntax
+		fn.initHTML(pkg.printFunc)
+		if syntax == nil {
+			fn.Synthetic = SyntheticLoadedFromExportData
+		} else {
+			// Note: we initialize fn.Blocks in
+			// (*builder).buildFunction and not here because Blocks
+			// being nil is used to indicate that building of the
+			// function hasn't started yet.
+
+			fn.functionBody = &functionBody{
+				scratchInstructions: make([]Instruction, avgBlocks*avgInstructionsPerBlock),
+			}
+		}
+
+		pkg.values[obj] = fn
+		pkg.Functions = append(pkg.Functions, fn)
+		if sig.Recv() == nil {
+			pkg.Members[name] = fn // package-level function
+		}
+
+	default: // (incl. *types.Package)
+		panic("unexpected Object type: " + obj.String())
+	}
+}
+
+// membersFromDecl populates package pkg with members for each
+// typechecker object (var, func, const or type) associated with the
+// specified decl.
+//
+func membersFromDecl(pkg *Package, decl ast.Decl) {
+	switch decl := decl.(type) {
+	case *ast.GenDecl: // import, const, type or var
+		switch decl.Tok {
+		case token.CONST:
+			for _, spec := range decl.Specs {
+				for _, id := range spec.(*ast.ValueSpec).Names {
+					if !isBlankIdent(id) {
+						memberFromObject(pkg, pkg.info.Defs[id], nil)
+					}
+				}
+			}
+
+		case token.VAR:
+			for _, spec := range decl.Specs {
+				for _, id := range spec.(*ast.ValueSpec).Names {
+					if !isBlankIdent(id) {
+						memberFromObject(pkg, pkg.info.Defs[id], spec)
+					}
+				}
+			}
+
+		case token.TYPE:
+			for _, spec := range decl.Specs {
+				id := spec.(*ast.TypeSpec).Name
+				if !isBlankIdent(id) {
+					memberFromObject(pkg, pkg.info.Defs[id], nil)
+				}
+			}
+		}
+
+	case *ast.FuncDecl:
+		id := decl.Name
+		if !isBlankIdent(id) {
+			memberFromObject(pkg, pkg.info.Defs[id], decl)
+		}
+	}
+}
+
+// CreatePackage constructs and returns an IR Package from the
+// specified type-checked, error-free file ASTs, and populates its
+// Members mapping.
+//
+// importable determines whether this package should be returned by a
+// subsequent call to ImportedPackage(pkg.Path()).
+//
+// The real work of building IR form for each function is not done
+// until a subsequent call to Package.Build().
+//
+func (prog *Program) CreatePackage(pkg *types.Package, files []*ast.File, info *types.Info, importable bool) *Package {
+	p := &Package{
+		Prog:      prog,
+		Members:   make(map[string]Member),
+		values:    make(map[types.Object]Value),
+		Pkg:       pkg,
+		info:      info,  // transient (CREATE and BUILD phases)
+		files:     files, // transient (CREATE and BUILD phases)
+		printFunc: prog.PrintFunc,
+	}
+
+	// Add init() function.
+	p.init = &Function{
+		name:         "init",
+		Signature:    new(types.Signature),
+		Synthetic:    SyntheticPackageInitializer,
+		Pkg:          p,
+		Prog:         prog,
+		functionBody: new(functionBody),
+	}
+	p.init.initHTML(prog.PrintFunc)
+	p.Members[p.init.name] = p.init
+	p.Functions = append(p.Functions, p.init)
+
+	// CREATE phase.
+	// Allocate all package members: vars, funcs, consts and types.
+	if len(files) > 0 {
+		// Go source package.
+		for _, file := range files {
+			for _, decl := range file.Decls {
+				membersFromDecl(p, decl)
+			}
+		}
+	} else {
+		// GC-compiled binary package (or "unsafe")
+		// No code.
+		// No position information.
+		scope := p.Pkg.Scope()
+		for _, name := range scope.Names() {
+			obj := scope.Lookup(name)
+			memberFromObject(p, obj, nil)
+			if obj, ok := obj.(*types.TypeName); ok {
+				if named, ok := obj.Type().(*types.Named); ok {
+					for i, n := 0, named.NumMethods(); i < n; i++ {
+						memberFromObject(p, named.Method(i), nil)
+					}
+				}
+			}
+		}
+	}
+
+	// Add initializer guard variable.
+	initguard := &Global{
+		Pkg:  p,
+		name: "init$guard",
+		typ:  types.NewPointer(tBool),
+	}
+	p.Members[initguard.Name()] = initguard
+
+	if prog.mode&GlobalDebug != 0 {
+		p.SetDebugMode(true)
+	}
+
+	if prog.mode&PrintPackages != 0 {
+		printMu.Lock()
+		p.WriteTo(os.Stdout)
+		printMu.Unlock()
+	}
+
+	if importable {
+		prog.imported[p.Pkg.Path()] = p
+	}
+	prog.packages[p.Pkg] = p
+
+	return p
+}
+
+// printMu serializes printing of Packages/Functions to stdout.
+var printMu sync.Mutex
+
+// AllPackages returns a new slice containing all packages in the
+// program prog in unspecified order.
+//
+func (prog *Program) AllPackages() []*Package {
+	pkgs := make([]*Package, 0, len(prog.packages))
+	for _, pkg := range prog.packages {
+		pkgs = append(pkgs, pkg)
+	}
+	return pkgs
+}
+
+// ImportedPackage returns the importable Package whose PkgPath
+// is path, or nil if no such Package has been created.
+//
+// A parameter to CreatePackage determines whether a package should be
+// considered importable. For example, no import declaration can resolve
+// to the ad-hoc main package created by 'go build foo.go'.
+//
+// TODO(adonovan): rethink this function and the "importable" concept;
+// most packages are importable. This function assumes that all
+// types.Package.Path values are unique within the ir.Program, which is
+// false---yet this function remains very convenient.
+// Clients should use (*Program).Package instead where possible.
+// IR doesn't really need a string-keyed map of packages.
+//
+func (prog *Program) ImportedPackage(path string) *Package {
+	return prog.imported[path]
+}

vendor/honnef.co/go/tools/go/ir/doc.go

@@ -0,0 +1,130 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ir defines a representation of the elements of Go programs
+// (packages, types, functions, variables and constants) using a
+// static single-information (SSI) form intermediate representation
+// (IR) for the bodies of functions.
+//
+// THIS INTERFACE IS EXPERIMENTAL AND IS LIKELY TO CHANGE.
+//
+// For an introduction to SSA form, upon which SSI builds, see
+// http://en.wikipedia.org/wiki/Static_single_assignment_form.
+// This page provides a broader reading list:
+// http://www.dcs.gla.ac.uk/~jsinger/ssa.html.
+//
+// For an introduction to SSI form, see The static single information
+// form by C. Scott Ananian.
+//
+// The level of abstraction of the IR form is intentionally close to
+// the source language to facilitate construction of source analysis
+// tools.  It is not intended for machine code generation.
+//
+// The simplest way to create the IR of a package is
+// to load typed syntax trees using golang.org/x/tools/go/packages, then
+// invoke the irutil.Packages helper function. See ExampleLoadPackages
+// and ExampleWholeProgram for examples.
+// The resulting ir.Program contains all the packages and their
+// members, but IR code is not created for function bodies until a
+// subsequent call to (*Package).Build or (*Program).Build.
+//
+// The builder initially builds a naive IR form in which all local
+// variables are addresses of stack locations with explicit loads and
+// stores.  Registerization of eligible locals and φ-node insertion
+// using dominance and dataflow are then performed as a second pass
+// called "lifting" to improve the accuracy and performance of
+// subsequent analyses; this pass can be skipped by setting the
+// NaiveForm builder flag.
+//
+// The primary interfaces of this package are:
+//
+//    - Member: a named member of a Go package.
+//    - Value: an expression that yields a value.
+//    - Instruction: a statement that consumes values and performs computation.
+//    - Node: a Value or Instruction (emphasizing its membership in the IR value graph)
+//
+// A computation that yields a result implements both the Value and
+// Instruction interfaces.  The following table shows for each
+// concrete type which of these interfaces it implements.
+//
+//                      Value?          Instruction?    Member?
+//   *Alloc                ✔               ✔
+//   *BinOp                ✔               ✔
+//   *BlankStore                           ✔
+//   *Builtin              ✔
+//   *Call                 ✔               ✔
+//   *ChangeInterface      ✔               ✔
+//   *ChangeType           ✔               ✔
+//   *Const                ✔               ✔
+//   *Convert              ✔               ✔
+//   *DebugRef                             ✔
+//   *Defer                ✔               ✔
+//   *Extract              ✔               ✔
+//   *Field                ✔               ✔
+//   *FieldAddr            ✔               ✔
+//   *FreeVar              ✔
+//   *Function             ✔                               ✔ (func)
+//   *Global               ✔                               ✔ (var)
+//   *Go                   ✔               ✔
+//   *If                                   ✔
+//   *Index                ✔               ✔
+//   *IndexAddr            ✔               ✔
+//   *Jump                                 ✔
+//   *Load                 ✔               ✔
+//   *MakeChan             ✔               ✔
+//   *MakeClosure          ✔               ✔
+//   *MakeInterface        ✔               ✔
+//   *MakeMap              ✔               ✔
+//   *MakeSlice            ✔               ✔
+//   *MapLookup            ✔               ✔
+//   *MapUpdate            ✔               ✔
+//   *NamedConst                                           ✔ (const)
+//   *Next                 ✔               ✔
+//   *Panic                                ✔
+//   *Parameter            ✔               ✔
+//   *Phi                  ✔               ✔
+//   *Range                ✔               ✔
+//   *Recv                 ✔               ✔
+//   *Return                               ✔
+//   *RunDefers                            ✔
+//   *Select               ✔               ✔
+//   *Send                 ✔               ✔
+//   *Sigma                ✔               ✔
+//   *Slice                ✔               ✔
+//   *SliceToArrayPointer  ✔               ✔
+//   *Store                ✔               ✔
+//   *StringLookup         ✔               ✔
+//   *Type                                                 ✔ (type)
+//   *TypeAssert           ✔               ✔
+//   *UnOp                 ✔               ✔
+//   *Unreachable                          ✔
+//
+// Other key types in this package include: Program, Package, Function
+// and BasicBlock.
+//
+// The program representation constructed by this package is fully
+// resolved internally, i.e. it does not rely on the names of Values,
+// Packages, Functions, Types or BasicBlocks for the correct
+// interpretation of the program.  Only the identities of objects and
+// the topology of the IR and type graphs are semantically
+// significant.  (There is one exception: Ids, used to identify field
+// and method names, contain strings.)  Avoidance of name-based
+// operations simplifies the implementation of subsequent passes and
+// can make them very efficient.  Many objects are nonetheless named
+// to aid in debugging, but it is not essential that the names be
+// either accurate or unambiguous.  The public API exposes a number of
+// name-based maps for client convenience.
+//
+// The ir/irutil package provides various utilities that depend only
+// on the public API of this package.
+//
+// TODO(adonovan): Consider the exceptional control-flow implications
+// of defer and recover().
+//
+// TODO(adonovan): write a how-to document for all the various cases
+// of trying to determine corresponding elements across the four
+// domains of source locations, ast.Nodes, types.Objects,
+// ir.Values/Instructions.
+//
+package ir

vendor/honnef.co/go/tools/go/ir/dom.go

@@ -0,0 +1,469 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines algorithms related to dominance.
+
+// Dominator tree construction ----------------------------------------
+//
+// We use the algorithm described in Lengauer & Tarjan. 1979.  A fast
+// algorithm for finding dominators in a flowgraph.
+// http://doi.acm.org/10.1145/357062.357071
+//
+// We also apply the optimizations to SLT described in Georgiadis et
+// al, Finding Dominators in Practice, JGAA 2006,
+// http://jgaa.info/accepted/2006/GeorgiadisTarjanWerneck2006.10.1.pdf
+// to avoid the need for buckets of size > 1.
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"math/big"
+	"os"
+	"sort"
+)
+
+// Idom returns the block that immediately dominates b:
+// its parent in the dominator tree, if any.
+// The entry node (b.Index==0) does not have a parent.
+//
+func (b *BasicBlock) Idom() *BasicBlock { return b.dom.idom }
+
+// Dominees returns the list of blocks that b immediately dominates:
+// its children in the dominator tree.
+//
+func (b *BasicBlock) Dominees() []*BasicBlock { return b.dom.children }
+
+// Dominates reports whether b dominates c.
+func (b *BasicBlock) Dominates(c *BasicBlock) bool {
+	return b.dom.pre <= c.dom.pre && c.dom.post <= b.dom.post
+}
+
+type byDomPreorder []*BasicBlock
+
+func (a byDomPreorder) Len() int           { return len(a) }
+func (a byDomPreorder) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a byDomPreorder) Less(i, j int) bool { return a[i].dom.pre < a[j].dom.pre }
+
+// DomPreorder returns a new slice containing the blocks of f in
+// dominator tree preorder.
+//
+func (f *Function) DomPreorder() []*BasicBlock {
+	n := len(f.Blocks)
+	order := make(byDomPreorder, n)
+	copy(order, f.Blocks)
+	sort.Sort(order)
+	return order
+}
+
+// domInfo contains a BasicBlock's dominance information.
+type domInfo struct {
+	idom      *BasicBlock   // immediate dominator (parent in domtree)
+	children  []*BasicBlock // nodes immediately dominated by this one
+	pre, post int32         // pre- and post-order numbering within domtree
+}
+
+// buildDomTree computes the dominator tree of f using the LT algorithm.
+// Precondition: all blocks are reachable (e.g. optimizeBlocks has been run).
+//
+func buildDomTree(fn *Function) {
+	// The step numbers refer to the original LT paper; the
+	// reordering is due to Georgiadis.
+
+	// Clear any previous domInfo.
+	for _, b := range fn.Blocks {
+		b.dom = domInfo{}
+	}
+
+	idoms := make([]*BasicBlock, len(fn.Blocks))
+
+	order := make([]*BasicBlock, 0, len(fn.Blocks))
+	seen := fn.blockset(0)
+	var dfs func(b *BasicBlock)
+	dfs = func(b *BasicBlock) {
+		if !seen.Add(b) {
+			return
+		}
+		for _, succ := range b.Succs {
+			dfs(succ)
+		}
+		if fn.fakeExits.Has(b) {
+			dfs(fn.Exit)
+		}
+		order = append(order, b)
+		b.post = len(order) - 1
+	}
+	dfs(fn.Blocks[0])
+
+	for i := 0; i < len(order)/2; i++ {
+		o := len(order) - i - 1
+		order[i], order[o] = order[o], order[i]
+	}
+
+	idoms[fn.Blocks[0].Index] = fn.Blocks[0]
+	changed := true
+	for changed {
+		changed = false
+		// iterate over all nodes in reverse postorder, except for the
+		// entry node
+		for _, b := range order[1:] {
+			var newIdom *BasicBlock
+			do := func(p *BasicBlock) {
+				if idoms[p.Index] == nil {
+					return
+				}
+				if newIdom == nil {
+					newIdom = p
+				} else {
+					finger1 := p
+					finger2 := newIdom
+					for finger1 != finger2 {
+						for finger1.post < finger2.post {
+							finger1 = idoms[finger1.Index]
+						}
+						for finger2.post < finger1.post {
+							finger2 = idoms[finger2.Index]
+						}
+					}
+					newIdom = finger1
+				}
+			}
+			for _, p := range b.Preds {
+				do(p)
+			}
+			if b == fn.Exit {
+				for _, p := range fn.Blocks {
+					if fn.fakeExits.Has(p) {
+						do(p)
+					}
+				}
+			}
+
+			if idoms[b.Index] != newIdom {
+				idoms[b.Index] = newIdom
+				changed = true
+			}
+		}
+	}
+
+	for i, b := range idoms {
+		fn.Blocks[i].dom.idom = b
+		if b == nil {
+			// malformed CFG
+			continue
+		}
+		if i == b.Index {
+			continue
+		}
+		b.dom.children = append(b.dom.children, fn.Blocks[i])
+	}
+
+	numberDomTree(fn.Blocks[0], 0, 0)
+
+	// printDomTreeDot(os.Stderr, fn) // debugging
+	// printDomTreeText(os.Stderr, root, 0) // debugging
+
+	if fn.Prog.mode&SanityCheckFunctions != 0 {
+		sanityCheckDomTree(fn)
+	}
+}
+
+// buildPostDomTree is like buildDomTree, but builds the post-dominator tree instead.
+func buildPostDomTree(fn *Function) {
+	// The step numbers refer to the original LT paper; the
+	// reordering is due to Georgiadis.
+
+	// Clear any previous domInfo.
+	for _, b := range fn.Blocks {
+		b.pdom = domInfo{}
+	}
+
+	idoms := make([]*BasicBlock, len(fn.Blocks))
+
+	order := make([]*BasicBlock, 0, len(fn.Blocks))
+	seen := fn.blockset(0)
+	var dfs func(b *BasicBlock)
+	dfs = func(b *BasicBlock) {
+		if !seen.Add(b) {
+			return
+		}
+		for _, pred := range b.Preds {
+			dfs(pred)
+		}
+		if b == fn.Exit {
+			for _, p := range fn.Blocks {
+				if fn.fakeExits.Has(p) {
+					dfs(p)
+				}
+			}
+		}
+		order = append(order, b)
+		b.post = len(order) - 1
+	}
+	dfs(fn.Exit)
+
+	for i := 0; i < len(order)/2; i++ {
+		o := len(order) - i - 1
+		order[i], order[o] = order[o], order[i]
+	}
+
+	idoms[fn.Exit.Index] = fn.Exit
+	changed := true
+	for changed {
+		changed = false
+		// iterate over all nodes in reverse postorder, except for the
+		// exit node
+		for _, b := range order[1:] {
+			var newIdom *BasicBlock
+			do := func(p *BasicBlock) {
+				if idoms[p.Index] == nil {
+					return
+				}
+				if newIdom == nil {
+					newIdom = p
+				} else {
+					finger1 := p
+					finger2 := newIdom
+					for finger1 != finger2 {
+						for finger1.post < finger2.post {
+							finger1 = idoms[finger1.Index]
+						}
+						for finger2.post < finger1.post {
+							finger2 = idoms[finger2.Index]
+						}
+					}
+					newIdom = finger1
+				}
+			}
+			for _, p := range b.Succs {
+				do(p)
+			}
+			if fn.fakeExits.Has(b) {
+				do(fn.Exit)
+			}
+
+			if idoms[b.Index] != newIdom {
+				idoms[b.Index] = newIdom
+				changed = true
+			}
+		}
+	}
+
+	for i, b := range idoms {
+		fn.Blocks[i].pdom.idom = b
+		if b == nil {
+			// malformed CFG
+			continue
+		}
+		if i == b.Index {
+			continue
+		}
+		b.pdom.children = append(b.pdom.children, fn.Blocks[i])
+	}
+
+	numberPostDomTree(fn.Exit, 0, 0)
+
+	// printPostDomTreeDot(os.Stderr, fn) // debugging
+	// printPostDomTreeText(os.Stderr, fn.Exit, 0) // debugging
+
+	if fn.Prog.mode&SanityCheckFunctions != 0 { // XXX
+		sanityCheckDomTree(fn) // XXX
+	}
+}
+
+// numberDomTree sets the pre- and post-order numbers of a depth-first
+// traversal of the dominator tree rooted at v.  These are used to
+// answer dominance queries in constant time.
+//
+func numberDomTree(v *BasicBlock, pre, post int32) (int32, int32) {
+	v.dom.pre = pre
+	pre++
+	for _, child := range v.dom.children {
+		pre, post = numberDomTree(child, pre, post)
+	}
+	v.dom.post = post
+	post++
+	return pre, post
+}
+
+// numberPostDomTree sets the pre- and post-order numbers of a depth-first
+// traversal of the post-dominator tree rooted at v.  These are used to
+// answer post-dominance queries in constant time.
+//
+func numberPostDomTree(v *BasicBlock, pre, post int32) (int32, int32) {
+	v.pdom.pre = pre
+	pre++
+	for _, child := range v.pdom.children {
+		pre, post = numberPostDomTree(child, pre, post)
+	}
+	v.pdom.post = post
+	post++
+	return pre, post
+}
+
+// Testing utilities ----------------------------------------
+
+// sanityCheckDomTree checks the correctness of the dominator tree
+// computed by the LT algorithm by comparing against the dominance
+// relation computed by a naive Kildall-style forward dataflow
+// analysis (Algorithm 10.16 from the "Dragon" book).
+//
+func sanityCheckDomTree(f *Function) {
+	n := len(f.Blocks)
+
+	// D[i] is the set of blocks that dominate f.Blocks[i],
+	// represented as a bit-set of block indices.
+	D := make([]big.Int, n)
+
+	one := big.NewInt(1)
+
+	// all is the set of all blocks; constant.
+	var all big.Int
+	all.Set(one).Lsh(&all, uint(n)).Sub(&all, one)
+
+	// Initialization.
+	for i := range f.Blocks {
+		if i == 0 {
+			// A root is dominated only by itself.
+			D[i].SetBit(&D[0], 0, 1)
+		} else {
+			// All other blocks are (initially) dominated
+			// by every block.
+			D[i].Set(&all)
+		}
+	}
+
+	// Iteration until fixed point.
+	for changed := true; changed; {
+		changed = false
+		for i, b := range f.Blocks {
+			if i == 0 {
+				continue
+			}
+			// Compute intersection across predecessors.
+			var x big.Int
+			x.Set(&all)
+			for _, pred := range b.Preds {
+				x.And(&x, &D[pred.Index])
+			}
+			if b == f.Exit {
+				for _, p := range f.Blocks {
+					if f.fakeExits.Has(p) {
+						x.And(&x, &D[p.Index])
+					}
+				}
+			}
+			x.SetBit(&x, i, 1) // a block always dominates itself.
+			if D[i].Cmp(&x) != 0 {
+				D[i].Set(&x)
+				changed = true
+			}
+		}
+	}
+
+	// Check the entire relation.  O(n^2).
+	ok := true
+	for i := 0; i < n; i++ {
+		for j := 0; j < n; j++ {
+			b, c := f.Blocks[i], f.Blocks[j]
+			actual := b.Dominates(c)
+			expected := D[j].Bit(i) == 1
+			if actual != expected {
+				fmt.Fprintf(os.Stderr, "dominates(%s, %s)==%t, want %t\n", b, c, actual, expected)
+				ok = false
+			}
+		}
+	}
+
+	preorder := f.DomPreorder()
+	for _, b := range f.Blocks {
+		if got := preorder[b.dom.pre]; got != b {
+			fmt.Fprintf(os.Stderr, "preorder[%d]==%s, want %s\n", b.dom.pre, got, b)
+			ok = false
+		}
+	}
+
+	if !ok {
+		panic("sanityCheckDomTree failed for " + f.String())
+	}
+
+}
+
+// Printing functions ----------------------------------------
+
+// printDomTree prints the dominator tree as text, using indentation.
+//lint:ignore U1000 used during debugging
+func printDomTreeText(buf *bytes.Buffer, v *BasicBlock, indent int) {
+	fmt.Fprintf(buf, "%*s%s\n", 4*indent, "", v)
+	for _, child := range v.dom.children {
+		printDomTreeText(buf, child, indent+1)
+	}
+}
+
+// printDomTreeDot prints the dominator tree of f in AT&T GraphViz
+// (.dot) format.
+//lint:ignore U1000 used during debugging
+func printDomTreeDot(buf io.Writer, f *Function) {
+	fmt.Fprintln(buf, "//", f)
+	fmt.Fprintln(buf, "digraph domtree {")
+	for i, b := range f.Blocks {
+		v := b.dom
+		fmt.Fprintf(buf, "\tn%d [label=\"%s (%d, %d)\",shape=\"rectangle\"];\n", v.pre, b, v.pre, v.post)
+		// TODO(adonovan): improve appearance of edges
+		// belonging to both dominator tree and CFG.
+
+		// Dominator tree edge.
+		if i != 0 {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"solid\",weight=100];\n", v.idom.dom.pre, v.pre)
+		}
+		// CFG edges.
+		for _, pred := range b.Preds {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"dotted\",weight=0];\n", pred.dom.pre, v.pre)
+		}
+
+		if f.fakeExits.Has(b) {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"dotted\",weight=0,color=red];\n", b.dom.pre, f.Exit.dom.pre)
+		}
+	}
+	fmt.Fprintln(buf, "}")
+}
+
+// printDomTree prints the dominator tree as text, using indentation.
+//lint:ignore U1000 used during debugging
+func printPostDomTreeText(buf io.Writer, v *BasicBlock, indent int) {
+	fmt.Fprintf(buf, "%*s%s\n", 4*indent, "", v)
+	for _, child := range v.pdom.children {
+		printPostDomTreeText(buf, child, indent+1)
+	}
+}
+
+// printDomTreeDot prints the dominator tree of f in AT&T GraphViz
+// (.dot) format.
+//lint:ignore U1000 used during debugging
+func printPostDomTreeDot(buf io.Writer, f *Function) {
+	fmt.Fprintln(buf, "//", f)
+	fmt.Fprintln(buf, "digraph pdomtree {")
+	for _, b := range f.Blocks {
+		v := b.pdom
+		fmt.Fprintf(buf, "\tn%d [label=\"%s (%d, %d)\",shape=\"rectangle\"];\n", v.pre, b, v.pre, v.post)
+		// TODO(adonovan): improve appearance of edges
+		// belonging to both dominator tree and CFG.
+
+		// Dominator tree edge.
+		if b != f.Exit {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"solid\",weight=100];\n", v.idom.pdom.pre, v.pre)
+		}
+		// CFG edges.
+		for _, pred := range b.Preds {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"dotted\",weight=0];\n", pred.pdom.pre, v.pre)
+		}
+
+		if f.fakeExits.Has(b) {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"dotted\",weight=0,color=red];\n", b.dom.pre, f.Exit.dom.pre)
+		}
+	}
+	fmt.Fprintln(buf, "}")
+}

vendor/honnef.co/go/tools/go/ir/emit.go

@@ -0,0 +1,495 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// Helpers for emitting IR instructions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"go/types"
+
+	"honnef.co/go/tools/go/types/typeutil"
+
+	"golang.org/x/exp/typeparams"
+)
+
+// emitNew emits to f a new (heap Alloc) instruction allocating an
+// object of type typ.  pos is the optional source location.
+//
+func emitNew(f *Function, typ types.Type, source ast.Node) *Alloc {
+	v := &Alloc{Heap: true}
+	v.setType(types.NewPointer(typ))
+	f.emit(v, source)
+	return v
+}
+
+// emitLoad emits to f an instruction to load the address addr into a
+// new temporary, and returns the value so defined.
+//
+func emitLoad(f *Function, addr Value, source ast.Node) *Load {
+	v := &Load{X: addr}
+	v.setType(deref(addr.Type()))
+	f.emit(v, source)
+	return v
+}
+
+func emitRecv(f *Function, ch Value, commaOk bool, typ types.Type, source ast.Node) Value {
+	recv := &Recv{
+		Chan:    ch,
+		CommaOk: commaOk,
+	}
+	recv.setType(typ)
+	return f.emit(recv, source)
+}
+
+// emitDebugRef emits to f a DebugRef pseudo-instruction associating
+// expression e with value v.
+//
+func emitDebugRef(f *Function, e ast.Expr, v Value, isAddr bool) {
+	ref := makeDebugRef(f, e, v, isAddr)
+	if ref == nil {
+		return
+	}
+	f.emit(ref, nil)
+}
+
+func makeDebugRef(f *Function, e ast.Expr, v Value, isAddr bool) *DebugRef {
+	if !f.debugInfo() {
+		return nil // debugging not enabled
+	}
+	if v == nil || e == nil {
+		panic("nil")
+	}
+	var obj types.Object
+	e = unparen(e)
+	if id, ok := e.(*ast.Ident); ok {
+		if isBlankIdent(id) {
+			return nil
+		}
+		obj = f.Pkg.objectOf(id)
+		switch obj.(type) {
+		case *types.Nil, *types.Const, *types.Builtin:
+			return nil
+		}
+	}
+	return &DebugRef{
+		X:      v,
+		Expr:   e,
+		IsAddr: isAddr,
+		object: obj,
+	}
+}
+
+// emitArith emits to f code to compute the binary operation op(x, y)
+// where op is an eager shift, logical or arithmetic operation.
+// (Use emitCompare() for comparisons and Builder.logicalBinop() for
+// non-eager operations.)
+//
+func emitArith(f *Function, op token.Token, x, y Value, t types.Type, source ast.Node) Value {
+	switch op {
+	case token.SHL, token.SHR:
+		x = emitConv(f, x, t, source)
+		// y may be signed or an 'untyped' constant.
+		// There is a runtime panic if y is signed and <0. Instead of inserting a check for y<0
+		// and converting to an unsigned value (like the compiler) leave y as is.
+		if b, ok := y.Type().Underlying().(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
+			// Untyped conversion:
+			// Spec https://go.dev/ref/spec#Operators:
+			// The right operand in a shift expression must have integer type or be an untyped constant
+			// representable by a value of type uint.
+			y = emitConv(f, y, types.Typ[types.Uint], source)
+		}
+
+	case token.ADD, token.SUB, token.MUL, token.QUO, token.REM, token.AND, token.OR, token.XOR, token.AND_NOT:
+		x = emitConv(f, x, t, source)
+		y = emitConv(f, y, t, source)
+
+	default:
+		panic("illegal op in emitArith: " + op.String())
+
+	}
+	v := &BinOp{
+		Op: op,
+		X:  x,
+		Y:  y,
+	}
+	v.setType(t)
+	return f.emit(v, source)
+}
+
+// emitCompare emits to f code compute the boolean result of
+// comparison comparison 'x op y'.
+//
+func emitCompare(f *Function, op token.Token, x, y Value, source ast.Node) Value {
+	xt := x.Type().Underlying()
+	yt := y.Type().Underlying()
+
+	// Special case to optimise a tagless SwitchStmt so that
+	// these are equivalent
+	//   switch { case e: ...}
+	//   switch true { case e: ... }
+	//   if e==true { ... }
+	// even in the case when e's type is an interface.
+	// TODO(adonovan): opt: generalise to x==true, false!=y, etc.
+	if x, ok := x.(*Const); ok && op == token.EQL && x.Value != nil && x.Value.Kind() == constant.Bool && constant.BoolVal(x.Value) {
+		if yt, ok := yt.(*types.Basic); ok && yt.Info()&types.IsBoolean != 0 {
+			return y
+		}
+	}
+
+	if types.Identical(xt, yt) {
+		// no conversion necessary
+	} else if _, ok := xt.(*types.Interface); ok && !typeparams.IsTypeParam(x.Type()) {
+		y = emitConv(f, y, x.Type(), source)
+	} else if _, ok := yt.(*types.Interface); ok && !typeparams.IsTypeParam(y.Type()) {
+		x = emitConv(f, x, y.Type(), source)
+	} else if _, ok := x.(*Const); ok {
+		x = emitConv(f, x, y.Type(), source)
+	} else if _, ok := y.(*Const); ok {
+		y = emitConv(f, y, x.Type(), source)
+		//lint:ignore SA9003 no-op
+	} else {
+		// other cases, e.g. channels.  No-op.
+	}
+
+	v := &BinOp{
+		Op: op,
+		X:  x,
+		Y:  y,
+	}
+	v.setType(tBool)
+	return f.emit(v, source)
+}
+
+// isValuePreserving returns true if a conversion from ut_src to
+// ut_dst is value-preserving, i.e. just a change of type.
+// Precondition: neither argument is a named type.
+//
+func isValuePreserving(ut_src, ut_dst types.Type) bool {
+	// Identical underlying types?
+	if types.IdenticalIgnoreTags(ut_dst, ut_src) {
+		return true
+	}
+
+	switch ut_dst.(type) {
+	case *types.Chan:
+		// Conversion between channel types?
+		_, ok := ut_src.(*types.Chan)
+		return ok
+
+	case *types.Pointer:
+		// Conversion between pointers with identical base types?
+		_, ok := ut_src.(*types.Pointer)
+		return ok
+	}
+	return false
+}
+
+// emitConv emits to f code to convert Value val to exactly type typ,
+// and returns the converted value.  Implicit conversions are required
+// by language assignability rules in assignments, parameter passing,
+// etc.
+//
+func emitConv(f *Function, val Value, t_dst types.Type, source ast.Node) Value {
+	t_src := val.Type()
+
+	// Identical types?  Conversion is a no-op.
+	if types.Identical(t_src, t_dst) {
+		return val
+	}
+
+	ut_dst := t_dst.Underlying()
+	ut_src := t_src.Underlying()
+
+	tset_dst := typeutil.NewTypeSet(ut_dst)
+	tset_src := typeutil.NewTypeSet(ut_src)
+
+	// Just a change of type, but not value or representation?
+	if tset_src.All(func(termSrc *typeparams.Term) bool {
+		return tset_dst.All(func(termDst *typeparams.Term) bool {
+			return isValuePreserving(termSrc.Type().Underlying(), termDst.Type().Underlying())
+		})
+	}) {
+		c := &ChangeType{X: val}
+		c.setType(t_dst)
+		return f.emit(c, source)
+	}
+
+	// Conversion to, or construction of a value of, an interface type?
+	if _, ok := ut_dst.(*types.Interface); ok && !typeparams.IsTypeParam(t_dst) {
+		// Assignment from one interface type to another?
+		if _, ok := ut_src.(*types.Interface); ok && !typeparams.IsTypeParam(t_src) {
+			c := &ChangeInterface{X: val}
+			c.setType(t_dst)
+			return f.emit(c, source)
+		}
+
+		// Untyped nil constant?  Return interface-typed nil constant.
+		if ut_src == tUntypedNil {
+			return emitConst(f, nilConst(t_dst))
+		}
+
+		// Convert (non-nil) "untyped" literals to their default type.
+		if t, ok := ut_src.(*types.Basic); ok && t.Info()&types.IsUntyped != 0 {
+			val = emitConv(f, val, types.Default(ut_src), source)
+		}
+
+		f.Pkg.Prog.needMethodsOf(val.Type())
+		mi := &MakeInterface{X: val}
+		mi.setType(t_dst)
+		return f.emit(mi, source)
+	}
+
+	// Conversion of a compile-time constant value? Note that converting a constant to a type parameter never results in
+	// a constant value.
+	if c, ok := val.(*Const); ok {
+		if _, ok := ut_dst.(*types.Basic); ok || c.IsNil() {
+			// Conversion of a compile-time constant to
+			// another constant type results in a new
+			// constant of the destination type and
+			// (initially) the same abstract value.
+			// We don't truncate the value yet.
+			return emitConst(f, NewConst(c.Value, t_dst))
+		}
+
+		// We're converting from constant to non-constant type,
+		// e.g. string -> []byte/[]rune.
+	}
+
+	// Conversion from slice to array pointer?
+	if tset_src.All(func(termSrc *typeparams.Term) bool {
+		return tset_dst.All(func(termDst *typeparams.Term) bool {
+			if slice, ok := termSrc.Type().Underlying().(*types.Slice); ok {
+				if ptr, ok := termDst.Type().Underlying().(*types.Pointer); ok {
+					if arr, ok := ptr.Elem().Underlying().(*types.Array); ok && types.Identical(slice.Elem(), arr.Elem()) {
+						return true
+					}
+				}
+			}
+			return false
+		})
+	}) {
+		c := &SliceToArrayPointer{X: val}
+		c.setType(t_dst)
+		return f.emit(c, source)
+	}
+
+	// A representation-changing conversion?
+	// At least one of {ut_src,ut_dst} must be *Basic.
+	// (The other may be []byte or []rune.)
+	ok1 := tset_src.Any(func(term *typeparams.Term) bool { _, ok := term.Type().Underlying().(*types.Basic); return ok })
+	ok2 := tset_dst.Any(func(term *typeparams.Term) bool { _, ok := term.Type().Underlying().(*types.Basic); return ok })
+	if ok1 || ok2 {
+		c := &Convert{X: val}
+		c.setType(t_dst)
+		return f.emit(c, source)
+	}
+
+	panic(fmt.Sprintf("in %s: cannot convert %s (%s) to %s", f, val, val.Type(), t_dst))
+}
+
+// emitStore emits to f an instruction to store value val at location
+// addr, applying implicit conversions as required by assignability rules.
+//
+func emitStore(f *Function, addr, val Value, source ast.Node) *Store {
+	s := &Store{
+		Addr: addr,
+		Val:  emitConv(f, val, deref(addr.Type()), source),
+	}
+	// make sure we call getMem after the call to emitConv, which may
+	// itself update the memory state
+	f.emit(s, source)
+	return s
+}
+
+// emitJump emits to f a jump to target, and updates the control-flow graph.
+// Postcondition: f.currentBlock is nil.
+//
+func emitJump(f *Function, target *BasicBlock, source ast.Node) *Jump {
+	b := f.currentBlock
+	j := new(Jump)
+	b.emit(j, source)
+	addEdge(b, target)
+	f.currentBlock = nil
+	return j
+}
+
+// emitIf emits to f a conditional jump to tblock or fblock based on
+// cond, and updates the control-flow graph.
+// Postcondition: f.currentBlock is nil.
+//
+func emitIf(f *Function, cond Value, tblock, fblock *BasicBlock, source ast.Node) *If {
+	b := f.currentBlock
+	stmt := &If{Cond: cond}
+	b.emit(stmt, source)
+	addEdge(b, tblock)
+	addEdge(b, fblock)
+	f.currentBlock = nil
+	return stmt
+}
+
+// emitExtract emits to f an instruction to extract the index'th
+// component of tuple.  It returns the extracted value.
+//
+func emitExtract(f *Function, tuple Value, index int, source ast.Node) Value {
+	e := &Extract{Tuple: tuple, Index: index}
+	e.setType(tuple.Type().(*types.Tuple).At(index).Type())
+	return f.emit(e, source)
+}
+
+// emitTypeAssert emits to f a type assertion value := x.(t) and
+// returns the value.  x.Type() must be an interface.
+//
+func emitTypeAssert(f *Function, x Value, t types.Type, source ast.Node) Value {
+	a := &TypeAssert{X: x, AssertedType: t}
+	a.setType(t)
+	return f.emit(a, source)
+}
+
+// emitTypeTest emits to f a type test value,ok := x.(t) and returns
+// a (value, ok) tuple.  x.Type() must be an interface.
+//
+func emitTypeTest(f *Function, x Value, t types.Type, source ast.Node) Value {
+	a := &TypeAssert{
+		X:            x,
+		AssertedType: t,
+		CommaOk:      true,
+	}
+	a.setType(types.NewTuple(
+		newVar("value", t),
+		varOk,
+	))
+	return f.emit(a, source)
+}
+
+// emitTailCall emits to f a function call in tail position.  The
+// caller is responsible for all fields of 'call' except its type.
+// Intended for wrapper methods.
+// Precondition: f does/will not use deferred procedure calls.
+// Postcondition: f.currentBlock is nil.
+//
+func emitTailCall(f *Function, call *Call, source ast.Node) {
+	tresults := f.Signature.Results()
+	nr := tresults.Len()
+	if nr == 1 {
+		call.typ = tresults.At(0).Type()
+	} else {
+		call.typ = tresults
+	}
+	tuple := f.emit(call, source)
+	var ret Return
+	switch nr {
+	case 0:
+		// no-op
+	case 1:
+		ret.Results = []Value{tuple}
+	default:
+		for i := 0; i < nr; i++ {
+			v := emitExtract(f, tuple, i, source)
+			// TODO(adonovan): in principle, this is required:
+			//   v = emitConv(f, o.Type, f.Signature.Results[i].Type)
+			// but in practice emitTailCall is only used when
+			// the types exactly match.
+			ret.Results = append(ret.Results, v)
+		}
+	}
+
+	f.Exit = f.newBasicBlock("exit")
+	emitJump(f, f.Exit, source)
+	f.currentBlock = f.Exit
+	f.emit(&ret, source)
+	f.currentBlock = nil
+}
+
+// emitImplicitSelections emits to f code to apply the sequence of
+// implicit field selections specified by indices to base value v, and
+// returns the selected value.
+//
+// If v is the address of a struct, the result will be the address of
+// a field; if it is the value of a struct, the result will be the
+// value of a field.
+//
+func emitImplicitSelections(f *Function, v Value, indices []int, source ast.Node) Value {
+	for _, index := range indices {
+		// We may have a generic type containing a pointer, or a pointer to a generic type containing a struct. A
+		// pointer to a generic containing a pointer to a struct shouldn't be possible because the outer pointer gets
+		// dereferenced implicitly before we get here.
+		fld := typeutil.CoreType(deref(v.Type())).Underlying().(*types.Struct).Field(index)
+
+		if isPointer(v.Type()) {
+			instr := &FieldAddr{
+				X:     v,
+				Field: index,
+			}
+			instr.setType(types.NewPointer(fld.Type()))
+			v = f.emit(instr, source)
+			// Load the field's value iff indirectly embedded.
+			if isPointer(fld.Type()) {
+				v = emitLoad(f, v, source)
+			}
+		} else {
+			instr := &Field{
+				X:     v,
+				Field: index,
+			}
+			instr.setType(fld.Type())
+			v = f.emit(instr, source)
+		}
+	}
+	return v
+}
+
+// emitFieldSelection emits to f code to select the index'th field of v.
+//
+// If wantAddr, the input must be a pointer-to-struct and the result
+// will be the field's address; otherwise the result will be the
+// field's value.
+// Ident id is used for position and debug info.
+//
+func emitFieldSelection(f *Function, v Value, index int, wantAddr bool, id *ast.Ident) Value {
+	// We may have a generic type containing a pointer, or a pointer to a generic type containing a struct. A
+	// pointer to a generic containing a pointer to a struct shouldn't be possible because the outer pointer gets
+	// dereferenced implicitly before we get here.
+	vut := typeutil.CoreType(deref(v.Type())).Underlying().(*types.Struct)
+	fld := vut.Field(index)
+	if isPointer(v.Type()) {
+		instr := &FieldAddr{
+			X:     v,
+			Field: index,
+		}
+		instr.setSource(id)
+		instr.setType(types.NewPointer(fld.Type()))
+		v = f.emit(instr, id)
+		// Load the field's value iff we don't want its address.
+		if !wantAddr {
+			v = emitLoad(f, v, id)
+		}
+	} else {
+		instr := &Field{
+			X:     v,
+			Field: index,
+		}
+		instr.setSource(id)
+		instr.setType(fld.Type())
+		v = f.emit(instr, id)
+	}
+	emitDebugRef(f, id, v, wantAddr)
+	return v
+}
+
+// zeroValue emits to f code to produce a zero value of type t,
+// and returns it.
+//
+func zeroValue(f *Function, t types.Type, source ast.Node) Value {
+	return emitConst(f, zeroConst(t))
+}
+
+func emitConst(f *Function, c Constant) Constant {
+	f.consts = append(f.consts, c)
+	return c
+}

vendor/honnef.co/go/tools/go/ir/exits.go

@@ -0,0 +1,356 @@
+package ir
+
+import (
+	"go/types"
+)
+
+func (b *builder) buildExits(fn *Function) {
+	if obj := fn.Object(); obj != nil {
+		switch obj.Pkg().Path() {
+		case "runtime":
+			switch obj.Name() {
+			case "exit":
+				fn.NoReturn = AlwaysExits
+				return
+			case "throw":
+				fn.NoReturn = AlwaysExits
+				return
+			case "Goexit":
+				fn.NoReturn = AlwaysUnwinds
+				return
+			}
+		case "go.uber.org/zap":
+			switch obj.(*types.Func).FullName() {
+			case "(*go.uber.org/zap.Logger).Fatal",
+				"(*go.uber.org/zap.SugaredLogger).Fatal",
+				"(*go.uber.org/zap.SugaredLogger).Fatalw",
+				"(*go.uber.org/zap.SugaredLogger).Fatalf":
+				// Technically, this method does not unconditionally exit
+				// the process. It dynamically calls a function stored in
+				// the logger. If the function is nil, it defaults to
+				// os.Exit.
+				//
+				// The main intent of this method is to terminate the
+				// process, and that's what the vast majority of people
+				// will use it for. We'll happily accept some false
+				// negatives to avoid a lot of false positives.
+				fn.NoReturn = AlwaysExits
+			case "(*go.uber.org/zap.Logger).Panic",
+				"(*go.uber.org/zap.SugaredLogger).Panicw",
+				"(*go.uber.org/zap.SugaredLogger).Panicf":
+				fn.NoReturn = AlwaysUnwinds
+				return
+			case "(*go.uber.org/zap.Logger).DPanic",
+				"(*go.uber.org/zap.SugaredLogger).DPanicf",
+				"(*go.uber.org/zap.SugaredLogger).DPanicw":
+				// These methods will only panic in development.
+			}
+		case "github.com/sirupsen/logrus":
+			switch obj.(*types.Func).FullName() {
+			case "(*github.com/sirupsen/logrus.Logger).Exit":
+				// Technically, this method does not unconditionally exit
+				// the process. It dynamically calls a function stored in
+				// the logger. If the function is nil, it defaults to
+				// os.Exit.
+				//
+				// The main intent of this method is to terminate the
+				// process, and that's what the vast majority of people
+				// will use it for. We'll happily accept some false
+				// negatives to avoid a lot of false positives.
+				fn.NoReturn = AlwaysExits
+				return
+			case "(*github.com/sirupsen/logrus.Logger).Panic",
+				"(*github.com/sirupsen/logrus.Logger).Panicf",
+				"(*github.com/sirupsen/logrus.Logger).Panicln":
+
+				// These methods will always panic, but that's not
+				// statically known from the code alone, because they
+				// take a detour through the generic Log methods.
+				fn.NoReturn = AlwaysUnwinds
+				return
+			case "(*github.com/sirupsen/logrus.Entry).Panicf",
+				"(*github.com/sirupsen/logrus.Entry).Panicln":
+
+				// Entry.Panic has an explicit panic, but Panicf and
+				// Panicln do not, relying fully on the generic Log
+				// method.
+				fn.NoReturn = AlwaysUnwinds
+				return
+			case "(*github.com/sirupsen/logrus.Logger).Log",
+				"(*github.com/sirupsen/logrus.Logger).Logf",
+				"(*github.com/sirupsen/logrus.Logger).Logln":
+				// TODO(dh): we cannot handle these cases. Whether they
+				// exit or unwind depends on the level, which is set
+				// via the first argument. We don't currently support
+				// call-site-specific exit information.
+			}
+		case "github.com/golang/glog":
+			switch obj.(*types.Func).FullName() {
+			case "github.com/golang/glog.Exit",
+				"github.com/golang/glog.ExitDepth",
+				"github.com/golang/glog.Exitf",
+				"github.com/golang/glog.Exitln",
+				"github.com/golang/glog.Fatal",
+				"github.com/golang/glog.FatalDepth",
+				"github.com/golang/glog.Fatalf",
+				"github.com/golang/glog.Fatalln":
+				// all of these call os.Exit after logging
+				fn.NoReturn = AlwaysExits
+			}
+		case "k8s.io/klog":
+			switch obj.(*types.Func).FullName() {
+			case "k8s.io/klog.Exit",
+				"k8s.io/klog.ExitDepth",
+				"k8s.io/klog.Exitf",
+				"k8s.io/klog.Exitln",
+				"k8s.io/klog.Fatal",
+				"k8s.io/klog.FatalDepth",
+				"k8s.io/klog.Fatalf",
+				"k8s.io/klog.Fatalln":
+				// all of these call os.Exit after logging
+				fn.NoReturn = AlwaysExits
+			}
+		}
+	}
+
+	isRecoverCall := func(instr Instruction) bool {
+		if instr, ok := instr.(*Call); ok {
+			if builtin, ok := instr.Call.Value.(*Builtin); ok {
+				if builtin.Name() == "recover" {
+					return true
+				}
+			}
+		}
+		return false
+	}
+
+	both := NewBlockSet(len(fn.Blocks))
+	exits := NewBlockSet(len(fn.Blocks))
+	unwinds := NewBlockSet(len(fn.Blocks))
+	recovers := false
+	for _, u := range fn.Blocks {
+		for _, instr := range u.Instrs {
+		instrSwitch:
+			switch instr := instr.(type) {
+			case *Defer:
+				if recovers {
+					// avoid doing extra work, we already know that this function calls recover
+					continue
+				}
+				call := instr.Call.StaticCallee()
+				if call == nil {
+					// not a static call, so we can't be sure the
+					// deferred call isn't calling recover
+					recovers = true
+					break
+				}
+				if call.Package() == fn.Package() {
+					b.buildFunction(call)
+				}
+				if len(call.Blocks) == 0 {
+					// external function, we don't know what's
+					// happening inside it
+					//
+					// TODO(dh): this includes functions from
+					// imported packages, due to how go/analysis
+					// works. We could introduce another fact,
+					// like we've done for exiting and unwinding.
+					recovers = true
+					break
+				}
+				for _, y := range call.Blocks {
+					for _, instr2 := range y.Instrs {
+						if isRecoverCall(instr2) {
+							recovers = true
+							break instrSwitch
+						}
+					}
+				}
+
+			case *Panic:
+				both.Add(u)
+				unwinds.Add(u)
+
+			case CallInstruction:
+				switch instr.(type) {
+				case *Defer, *Call:
+				default:
+					continue
+				}
+				if instr.Common().IsInvoke() {
+					// give up
+					return
+				}
+				var call *Function
+				switch instr.Common().Value.(type) {
+				case *Function, *MakeClosure:
+					call = instr.Common().StaticCallee()
+				case *Builtin:
+					// the only builtins that affect control flow are
+					// panic and recover, and we've already handled
+					// those
+					continue
+				default:
+					// dynamic dispatch
+					return
+				}
+				// buildFunction is idempotent. if we're part of a
+				// (mutually) recursive call chain, then buildFunction
+				// will immediately return, and fn.WillExit will be false.
+				if call.Package() == fn.Package() {
+					b.buildFunction(call)
+				}
+				switch call.NoReturn {
+				case AlwaysExits:
+					both.Add(u)
+					exits.Add(u)
+				case AlwaysUnwinds:
+					both.Add(u)
+					unwinds.Add(u)
+				case NeverReturns:
+					both.Add(u)
+				}
+			}
+		}
+	}
+
+	// depth-first search trying to find a path to the exit block that
+	// doesn't cross any of the blacklisted blocks
+	seen := NewBlockSet(len(fn.Blocks))
+	var findPath func(root *BasicBlock, bl *BlockSet) bool
+	findPath = func(root *BasicBlock, bl *BlockSet) bool {
+		if root == fn.Exit {
+			return true
+		}
+		if seen.Has(root) {
+			return false
+		}
+		if bl.Has(root) {
+			return false
+		}
+		seen.Add(root)
+		for _, succ := range root.Succs {
+			if findPath(succ, bl) {
+				return true
+			}
+		}
+		return false
+	}
+	findPathEntry := func(root *BasicBlock, bl *BlockSet) bool {
+		if bl.Num() == 0 {
+			return true
+		}
+		seen.Clear()
+		return findPath(root, bl)
+	}
+
+	if !findPathEntry(fn.Blocks[0], exits) {
+		fn.NoReturn = AlwaysExits
+	} else if !recovers {
+		// Only consider unwinding and "never returns" if we don't
+		// call recover. If we do call recover, then panics don't
+		// bubble up the stack.
+
+		// TODO(dh): the position of the defer matters. If we
+		// unconditionally terminate before we defer a recover, then
+		// the recover is ineffective.
+
+		if !findPathEntry(fn.Blocks[0], unwinds) {
+			fn.NoReturn = AlwaysUnwinds
+		} else if !findPathEntry(fn.Blocks[0], both) {
+			fn.NoReturn = NeverReturns
+		}
+	}
+}
+
+func (b *builder) addUnreachables(fn *Function) {
+	var unreachable *BasicBlock
+
+	for _, bb := range fn.Blocks {
+	instrLoop:
+		for i, instr := range bb.Instrs {
+			if instr, ok := instr.(*Call); ok {
+				var call *Function
+				switch v := instr.Common().Value.(type) {
+				case *Function:
+					call = v
+				case *MakeClosure:
+					call = v.Fn.(*Function)
+				}
+				if call == nil {
+					continue
+				}
+				if call.Package() == fn.Package() {
+					// make sure we have information on all functions in this package
+					b.buildFunction(call)
+				}
+				switch call.NoReturn {
+				case AlwaysExits:
+					// This call will cause the process to terminate.
+					// Remove remaining instructions in the block and
+					// replace any control flow with Unreachable.
+					for _, succ := range bb.Succs {
+						succ.removePred(bb)
+					}
+					bb.Succs = bb.Succs[:0]
+
+					bb.Instrs = bb.Instrs[:i+1]
+					bb.emit(new(Unreachable), instr.Source())
+					addEdge(bb, fn.Exit)
+					break instrLoop
+
+				case AlwaysUnwinds:
+					// This call will cause the goroutine to terminate
+					// and defers to run (i.e. a panic or
+					// runtime.Goexit). Remove remaining instructions
+					// in the block and replace any control flow with
+					// an unconditional jump to the exit block.
+					for _, succ := range bb.Succs {
+						succ.removePred(bb)
+					}
+					bb.Succs = bb.Succs[:0]
+
+					bb.Instrs = bb.Instrs[:i+1]
+					bb.emit(new(Jump), instr.Source())
+					addEdge(bb, fn.Exit)
+					break instrLoop
+
+				case NeverReturns:
+					// This call will either cause the goroutine to
+					// terminate, or the process to terminate. Remove
+					// remaining instructions in the block and replace
+					// any control flow with a conditional jump to
+					// either the exit block, or Unreachable.
+					for _, succ := range bb.Succs {
+						succ.removePred(bb)
+					}
+					bb.Succs = bb.Succs[:0]
+
+					bb.Instrs = bb.Instrs[:i+1]
+					var c Call
+					c.Call.Value = &Builtin{
+						name: "ir:noreturnWasPanic",
+						sig: types.NewSignature(nil,
+							types.NewTuple(),
+							types.NewTuple(anonVar(types.Typ[types.Bool])),
+							false,
+						),
+					}
+					c.setType(types.Typ[types.Bool])
+
+					if unreachable == nil {
+						unreachable = fn.newBasicBlock("unreachable")
+						unreachable.emit(&Unreachable{}, nil)
+						addEdge(unreachable, fn.Exit)
+					}
+
+					bb.emit(&c, instr.Source())
+					bb.emit(&If{Cond: &c}, instr.Source())
+					addEdge(bb, fn.Exit)
+					addEdge(bb, unreachable)
+					break instrLoop
+				}
+			}
+		}
+	}
+}

vendor/honnef.co/go/tools/go/ir/irutil/load.go

@@ -0,0 +1,184 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package irutil
+
+// This file defines utility functions for constructing programs in IR form.
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"honnef.co/go/tools/go/ir"
+
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/packages"
+)
+
+type Options struct {
+	// Which function, if any, to print in HTML form
+	PrintFunc string
+}
+
+// Packages creates an IR program for a set of packages.
+//
+// The packages must have been loaded from source syntax using the
+// golang.org/x/tools/go/packages.Load function in LoadSyntax or
+// LoadAllSyntax mode.
+//
+// Packages creates an IR package for each well-typed package in the
+// initial list, plus all their dependencies. The resulting list of
+// packages corresponds to the list of initial packages, and may contain
+// a nil if IR code could not be constructed for the corresponding initial
+// package due to type errors.
+//
+// Code for bodies of functions is not built until Build is called on
+// the resulting Program. IR code is constructed only for the initial
+// packages with well-typed syntax trees.
+//
+// The mode parameter controls diagnostics and checking during IR construction.
+//
+func Packages(initial []*packages.Package, mode ir.BuilderMode, opts *Options) (*ir.Program, []*ir.Package) {
+	return doPackages(initial, mode, false, opts)
+}
+
+// AllPackages creates an IR program for a set of packages plus all
+// their dependencies.
+//
+// The packages must have been loaded from source syntax using the
+// golang.org/x/tools/go/packages.Load function in LoadAllSyntax mode.
+//
+// AllPackages creates an IR package for each well-typed package in the
+// initial list, plus all their dependencies. The resulting list of
+// packages corresponds to the list of initial packages, and may contain
+// a nil if IR code could not be constructed for the corresponding
+// initial package due to type errors.
+//
+// Code for bodies of functions is not built until Build is called on
+// the resulting Program. IR code is constructed for all packages with
+// well-typed syntax trees.
+//
+// The mode parameter controls diagnostics and checking during IR construction.
+//
+func AllPackages(initial []*packages.Package, mode ir.BuilderMode, opts *Options) (*ir.Program, []*ir.Package) {
+	return doPackages(initial, mode, true, opts)
+}
+
+func doPackages(initial []*packages.Package, mode ir.BuilderMode, deps bool, opts *Options) (*ir.Program, []*ir.Package) {
+
+	var fset *token.FileSet
+	if len(initial) > 0 {
+		fset = initial[0].Fset
+	}
+
+	prog := ir.NewProgram(fset, mode)
+	if opts != nil {
+		prog.PrintFunc = opts.PrintFunc
+	}
+
+	isInitial := make(map[*packages.Package]bool, len(initial))
+	for _, p := range initial {
+		isInitial[p] = true
+	}
+
+	irmap := make(map[*packages.Package]*ir.Package)
+	packages.Visit(initial, nil, func(p *packages.Package) {
+		if p.Types != nil && !p.IllTyped {
+			var files []*ast.File
+			if deps || isInitial[p] {
+				files = p.Syntax
+			}
+			irmap[p] = prog.CreatePackage(p.Types, files, p.TypesInfo, true)
+		}
+	})
+
+	var irpkgs []*ir.Package
+	for _, p := range initial {
+		irpkgs = append(irpkgs, irmap[p]) // may be nil
+	}
+	return prog, irpkgs
+}
+
+// CreateProgram returns a new program in IR form, given a program
+// loaded from source.  An IR package is created for each transitively
+// error-free package of lprog.
+//
+// Code for bodies of functions is not built until Build is called
+// on the result.
+//
+// The mode parameter controls diagnostics and checking during IR construction.
+//
+// Deprecated: use golang.org/x/tools/go/packages and the Packages
+// function instead; see ir.ExampleLoadPackages.
+//
+func CreateProgram(lprog *loader.Program, mode ir.BuilderMode) *ir.Program {
+	prog := ir.NewProgram(lprog.Fset, mode)
+
+	for _, info := range lprog.AllPackages {
+		if info.TransitivelyErrorFree {
+			prog.CreatePackage(info.Pkg, info.Files, &info.Info, info.Importable)
+		}
+	}
+
+	return prog
+}
+
+// BuildPackage builds an IR program with IR for a single package.
+//
+// It populates pkg by type-checking the specified file ASTs.  All
+// dependencies are loaded using the importer specified by tc, which
+// typically loads compiler export data; IR code cannot be built for
+// those packages.  BuildPackage then constructs an ir.Program with all
+// dependency packages created, and builds and returns the IR package
+// corresponding to pkg.
+//
+// The caller must have set pkg.Path() to the import path.
+//
+// The operation fails if there were any type-checking or import errors.
+//
+// See ../ir/example_test.go for an example.
+//
+func BuildPackage(tc *types.Config, fset *token.FileSet, pkg *types.Package, files []*ast.File, mode ir.BuilderMode) (*ir.Package, *types.Info, error) {
+	if fset == nil {
+		panic("no token.FileSet")
+	}
+	if pkg.Path() == "" {
+		panic("package has no import path")
+	}
+
+	info := &types.Info{
+		Types:      make(map[ast.Expr]types.TypeAndValue),
+		Defs:       make(map[*ast.Ident]types.Object),
+		Uses:       make(map[*ast.Ident]types.Object),
+		Implicits:  make(map[ast.Node]types.Object),
+		Scopes:     make(map[ast.Node]*types.Scope),
+		Selections: make(map[*ast.SelectorExpr]*types.Selection),
+	}
+	if err := types.NewChecker(tc, fset, pkg, info).Files(files); err != nil {
+		return nil, nil, err
+	}
+
+	prog := ir.NewProgram(fset, mode)
+
+	// Create IR packages for all imports.
+	// Order is not significant.
+	created := make(map[*types.Package]bool)
+	var createAll func(pkgs []*types.Package)
+	createAll = func(pkgs []*types.Package) {
+		for _, p := range pkgs {
+			if !created[p] {
+				created[p] = true
+				prog.CreatePackage(p, nil, nil, true)
+				createAll(p.Imports())
+			}
+		}
+	}
+	createAll(pkg.Imports())
+
+	// Create and build the primary package.
+	irpkg := prog.CreatePackage(pkg, files, info, false)
+	irpkg.Build()
+	return irpkg, info, nil
+}

vendor/honnef.co/go/tools/go/ir/irutil/loops.go

@@ -0,0 +1,54 @@
+package irutil
+
+import "honnef.co/go/tools/go/ir"
+
+type Loop struct{ *ir.BlockSet }
+
+func FindLoops(fn *ir.Function) []Loop {
+	if fn.Blocks == nil {
+		return nil
+	}
+	tree := fn.DomPreorder()
+	var sets []Loop
+	for _, h := range tree {
+		for _, n := range h.Preds {
+			if !h.Dominates(n) {
+				continue
+			}
+			// n is a back-edge to h
+			// h is the loop header
+			if n == h {
+				set := Loop{ir.NewBlockSet(len(fn.Blocks))}
+				set.Add(n)
+				sets = append(sets, set)
+				continue
+			}
+			set := Loop{ir.NewBlockSet(len(fn.Blocks))}
+			set.Add(h)
+			set.Add(n)
+			for _, b := range allPredsBut(n, h, nil) {
+				set.Add(b)
+			}
+			sets = append(sets, set)
+		}
+	}
+	return sets
+}
+
+func allPredsBut(b, but *ir.BasicBlock, list []*ir.BasicBlock) []*ir.BasicBlock {
+outer:
+	for _, pred := range b.Preds {
+		if pred == but {
+			continue
+		}
+		for _, p := range list {
+			// TODO improve big-o complexity of this function
+			if pred == p {
+				continue outer
+			}
+		}
+		list = append(list, pred)
+		list = allPredsBut(pred, but, list)
+	}
+	return list
+}

vendor/honnef.co/go/tools/go/ir/irutil/stub.go

@@ -0,0 +1,32 @@
+package irutil
+
+import (
+	"honnef.co/go/tools/go/ir"
+)
+
+// IsStub reports whether a function is a stub. A function is
+// considered a stub if it has no instructions or if all it does is
+// return a constant value.
+func IsStub(fn *ir.Function) bool {
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			switch instr.(type) {
+			case *ir.Const:
+				// const naturally has no side-effects
+			case *ir.Panic:
+				// panic is a stub if it only uses constants
+			case *ir.Return:
+				// return is a stub if it only uses constants
+			case *ir.DebugRef:
+			case *ir.Jump:
+				// if there are no disallowed instructions, then we're
+				// only jumping to the exit block (or possibly
+				// somewhere else that's stubby?)
+			default:
+				// all other instructions are assumed to do actual work
+				return false
+			}
+		}
+	}
+	return true
+}

vendor/honnef.co/go/tools/go/ir/irutil/switch.go

@@ -0,0 +1,264 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package irutil
+
+// This file implements discovery of switch and type-switch constructs
+// from low-level control flow.
+//
+// Many techniques exist for compiling a high-level switch with
+// constant cases to efficient machine code.  The optimal choice will
+// depend on the data type, the specific case values, the code in the
+// body of each case, and the hardware.
+// Some examples:
+// - a lookup table (for a switch that maps constants to constants)
+// - a computed goto
+// - a binary tree
+// - a perfect hash
+// - a two-level switch (to partition constant strings by their first byte).
+
+import (
+	"bytes"
+	"fmt"
+	"go/token"
+	"go/types"
+
+	"honnef.co/go/tools/go/ir"
+)
+
+// A ConstCase represents a single constant comparison.
+// It is part of a Switch.
+type ConstCase struct {
+	Block *ir.BasicBlock // block performing the comparison
+	Body  *ir.BasicBlock // body of the case
+	Value *ir.Const      // case comparand
+}
+
+// A TypeCase represents a single type assertion.
+// It is part of a Switch.
+type TypeCase struct {
+	Block   *ir.BasicBlock // block performing the type assert
+	Body    *ir.BasicBlock // body of the case
+	Type    types.Type     // case type
+	Binding ir.Value       // value bound by this case
+}
+
+// A Switch is a logical high-level control flow operation
+// (a multiway branch) discovered by analysis of a CFG containing
+// only if/else chains.  It is not part of the ir.Instruction set.
+//
+// One of ConstCases and TypeCases has length >= 2;
+// the other is nil.
+//
+// In a value switch, the list of cases may contain duplicate constants.
+// A type switch may contain duplicate types, or types assignable
+// to an interface type also in the list.
+// TODO(adonovan): eliminate such duplicates.
+//
+type Switch struct {
+	Start      *ir.BasicBlock // block containing start of if/else chain
+	X          ir.Value       // the switch operand
+	ConstCases []ConstCase    // ordered list of constant comparisons
+	TypeCases  []TypeCase     // ordered list of type assertions
+	Default    *ir.BasicBlock // successor if all comparisons fail
+}
+
+func (sw *Switch) String() string {
+	// We represent each block by the String() of its
+	// first Instruction, e.g. "print(42:int)".
+	var buf bytes.Buffer
+	if sw.ConstCases != nil {
+		fmt.Fprintf(&buf, "switch %s {\n", sw.X.Name())
+		for _, c := range sw.ConstCases {
+			fmt.Fprintf(&buf, "case %s: %s\n", c.Value.Name(), c.Body.Instrs[0])
+		}
+	} else {
+		fmt.Fprintf(&buf, "switch %s.(type) {\n", sw.X.Name())
+		for _, c := range sw.TypeCases {
+			fmt.Fprintf(&buf, "case %s %s: %s\n",
+				c.Binding.Name(), c.Type, c.Body.Instrs[0])
+		}
+	}
+	if sw.Default != nil {
+		fmt.Fprintf(&buf, "default: %s\n", sw.Default.Instrs[0])
+	}
+	fmt.Fprintf(&buf, "}")
+	return buf.String()
+}
+
+// Switches examines the control-flow graph of fn and returns the
+// set of inferred value and type switches.  A value switch tests an
+// ir.Value for equality against two or more compile-time constant
+// values.  Switches involving link-time constants (addresses) are
+// ignored.  A type switch type-asserts an ir.Value against two or
+// more types.
+//
+// The switches are returned in dominance order.
+//
+// The resulting switches do not necessarily correspond to uses of the
+// 'switch' keyword in the source: for example, a single source-level
+// switch statement with non-constant cases may result in zero, one or
+// many Switches, one per plural sequence of constant cases.
+// Switches may even be inferred from if/else- or goto-based control flow.
+// (In general, the control flow constructs of the source program
+// cannot be faithfully reproduced from the IR.)
+//
+func Switches(fn *ir.Function) []Switch {
+	// Traverse the CFG in dominance order, so we don't
+	// enter an if/else-chain in the middle.
+	var switches []Switch
+	seen := make(map[*ir.BasicBlock]bool) // TODO(adonovan): opt: use ir.blockSet
+	for _, b := range fn.DomPreorder() {
+		if x, k := isComparisonBlock(b); x != nil {
+			// Block b starts a switch.
+			sw := Switch{Start: b, X: x}
+			valueSwitch(&sw, k, seen)
+			if len(sw.ConstCases) > 1 {
+				switches = append(switches, sw)
+			}
+		}
+
+		if y, x, T := isTypeAssertBlock(b); y != nil {
+			// Block b starts a type switch.
+			sw := Switch{Start: b, X: x}
+			typeSwitch(&sw, y, T, seen)
+			if len(sw.TypeCases) > 1 {
+				switches = append(switches, sw)
+			}
+		}
+	}
+	return switches
+}
+
+func isSameX(x1 ir.Value, x2 ir.Value) bool {
+	if x1 == x2 {
+		return true
+	}
+	if x2, ok := x2.(*ir.Sigma); ok {
+		return isSameX(x1, x2.X)
+	}
+	return false
+}
+
+func valueSwitch(sw *Switch, k *ir.Const, seen map[*ir.BasicBlock]bool) {
+	b := sw.Start
+	x := sw.X
+	for isSameX(sw.X, x) {
+		if seen[b] {
+			break
+		}
+		seen[b] = true
+
+		sw.ConstCases = append(sw.ConstCases, ConstCase{
+			Block: b,
+			Body:  b.Succs[0],
+			Value: k,
+		})
+		b = b.Succs[1]
+		n := 0
+		for _, instr := range b.Instrs {
+			switch instr.(type) {
+			case *ir.If, *ir.BinOp:
+				n++
+			case *ir.Sigma, *ir.Phi, *ir.DebugRef:
+			default:
+				n += 1000
+			}
+		}
+		if n != 2 {
+			// Block b contains not just 'if x == k' and σ/ϕ nodes,
+			// so it may have side effects that
+			// make it unsafe to elide.
+			break
+		}
+		if len(b.Preds) != 1 {
+			// Block b has multiple predecessors,
+			// so it cannot be treated as a case.
+			break
+		}
+		x, k = isComparisonBlock(b)
+	}
+	sw.Default = b
+}
+
+func typeSwitch(sw *Switch, y ir.Value, T types.Type, seen map[*ir.BasicBlock]bool) {
+	b := sw.Start
+	x := sw.X
+	for isSameX(sw.X, x) {
+		if seen[b] {
+			break
+		}
+		seen[b] = true
+
+		sw.TypeCases = append(sw.TypeCases, TypeCase{
+			Block:   b,
+			Body:    b.Succs[0],
+			Type:    T,
+			Binding: y,
+		})
+		b = b.Succs[1]
+		n := 0
+		for _, instr := range b.Instrs {
+			switch instr.(type) {
+			case *ir.TypeAssert, *ir.Extract, *ir.If:
+				n++
+			case *ir.Sigma, *ir.Phi:
+			default:
+				n += 1000
+			}
+		}
+		if n != 4 {
+			// Block b contains not just
+			//  {TypeAssert; Extract #0; Extract #1; If}
+			// so it may have side effects that
+			// make it unsafe to elide.
+			break
+		}
+		if len(b.Preds) != 1 {
+			// Block b has multiple predecessors,
+			// so it cannot be treated as a case.
+			break
+		}
+		y, x, T = isTypeAssertBlock(b)
+	}
+	sw.Default = b
+}
+
+// isComparisonBlock returns the operands (v, k) if a block ends with
+// a comparison v==k, where k is a compile-time constant.
+//
+func isComparisonBlock(b *ir.BasicBlock) (v ir.Value, k *ir.Const) {
+	if n := len(b.Instrs); n >= 2 {
+		if i, ok := b.Instrs[n-1].(*ir.If); ok {
+			if binop, ok := i.Cond.(*ir.BinOp); ok && binop.Block() == b && binop.Op == token.EQL {
+				if k, ok := binop.Y.(*ir.Const); ok {
+					return binop.X, k
+				}
+				if k, ok := binop.X.(*ir.Const); ok {
+					return binop.Y, k
+				}
+			}
+		}
+	}
+	return
+}
+
+// isTypeAssertBlock returns the operands (y, x, T) if a block ends with
+// a type assertion "if y, ok := x.(T); ok {".
+//
+func isTypeAssertBlock(b *ir.BasicBlock) (y, x ir.Value, T types.Type) {
+	if n := len(b.Instrs); n >= 4 {
+		if i, ok := b.Instrs[n-1].(*ir.If); ok {
+			if ext1, ok := i.Cond.(*ir.Extract); ok && ext1.Block() == b && ext1.Index == 1 {
+				if ta, ok := ext1.Tuple.(*ir.TypeAssert); ok && ta.Block() == b {
+					// hack: relies upon instruction ordering.
+					if ext0, ok := b.Instrs[n-3].(*ir.Extract); ok {
+						return ext0, ta.X, ta.AssertedType
+					}
+				}
+			}
+		}
+	}
+	return
+}

vendor/honnef.co/go/tools/go/ir/irutil/terminates.go

@@ -0,0 +1,70 @@
+package irutil
+
+import (
+	"go/types"
+
+	"honnef.co/go/tools/go/ir"
+)
+
+// Terminates reports whether fn is supposed to return, that is if it
+// has at least one theoretic path that returns from the function.
+// Explicit panics do not count as terminating.
+func Terminates(fn *ir.Function) bool {
+	if fn.Blocks == nil {
+		// assuming that a function terminates is the conservative
+		// choice
+		return true
+	}
+
+	for _, block := range fn.Blocks {
+		if _, ok := block.Control().(*ir.Return); ok {
+			if len(block.Preds) == 0 {
+				return true
+			}
+			for _, pred := range block.Preds {
+				switch ctrl := pred.Control().(type) {
+				case *ir.Panic:
+					// explicit panics do not count as terminating
+				case *ir.If:
+					// Check if we got here by receiving from a closed
+					// time.Tick channel – this cannot happen at
+					// runtime and thus doesn't constitute termination
+					iff := ctrl
+					if !ok {
+						return true
+					}
+					ex, ok := iff.Cond.(*ir.Extract)
+					if !ok {
+						return true
+					}
+					if ex.Index != 1 {
+						return true
+					}
+					recv, ok := ex.Tuple.(*ir.Recv)
+					if !ok {
+						return true
+					}
+					call, ok := recv.Chan.(*ir.Call)
+					if !ok {
+						return true
+					}
+					fn, ok := call.Common().Value.(*ir.Function)
+					if !ok {
+						return true
+					}
+					fn2, ok := fn.Object().(*types.Func)
+					if !ok {
+						return true
+					}
+					if fn2.FullName() != "time.Tick" {
+						return true
+					}
+				default:
+					// we've reached the exit block
+					return true
+				}
+			}
+		}
+	}
+	return false
+}

vendor/honnef.co/go/tools/go/ir/irutil/util.go

@@ -0,0 +1,178 @@
+package irutil
+
+import (
+	"go/types"
+	"strings"
+
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/go/types/typeutil"
+)
+
+func Reachable(from, to *ir.BasicBlock) bool {
+	if from == to {
+		return true
+	}
+	if from.Dominates(to) {
+		return true
+	}
+
+	found := false
+	Walk(from, func(b *ir.BasicBlock) bool {
+		if b == to {
+			found = true
+			return false
+		}
+		return true
+	})
+	return found
+}
+
+func Walk(b *ir.BasicBlock, fn func(*ir.BasicBlock) bool) {
+	seen := map[*ir.BasicBlock]bool{}
+	wl := []*ir.BasicBlock{b}
+	for len(wl) > 0 {
+		b := wl[len(wl)-1]
+		wl = wl[:len(wl)-1]
+		if seen[b] {
+			continue
+		}
+		seen[b] = true
+		if !fn(b) {
+			continue
+		}
+		wl = append(wl, b.Succs...)
+	}
+}
+
+func Vararg(x *ir.Slice) ([]ir.Value, bool) {
+	var out []ir.Value
+	alloc, ok := ir.Unwrap(x.X).(*ir.Alloc)
+	if !ok {
+		return nil, false
+	}
+	var checkAlloc func(alloc ir.Value) bool
+	checkAlloc = func(alloc ir.Value) bool {
+		for _, ref := range *alloc.Referrers() {
+			if ref == x {
+				continue
+			}
+			if ref.Block() != x.Block() {
+				return false
+			}
+			switch ref := ref.(type) {
+			case *ir.IndexAddr:
+				idx := ref
+				if len(*idx.Referrers()) != 1 {
+					return false
+				}
+				store, ok := (*idx.Referrers())[0].(*ir.Store)
+				if !ok {
+					return false
+				}
+				out = append(out, store.Val)
+			case *ir.Copy:
+				if !checkAlloc(ref) {
+					return false
+				}
+			default:
+				return false
+			}
+		}
+		return true
+	}
+	if !checkAlloc(alloc) {
+		return nil, false
+	}
+	return out, true
+}
+
+func CallName(call *ir.CallCommon) string {
+	if call.IsInvoke() {
+		return ""
+	}
+	switch v := call.Value.(type) {
+	case *ir.Function:
+		fn, ok := v.Object().(*types.Func)
+		if !ok {
+			return ""
+		}
+		return typeutil.FuncName(fn)
+	case *ir.Builtin:
+		return v.Name()
+	}
+	return ""
+}
+
+func IsCallTo(call *ir.CallCommon, name string) bool { return CallName(call) == name }
+
+func IsCallToAny(call *ir.CallCommon, names ...string) bool {
+	q := CallName(call)
+	for _, name := range names {
+		if q == name {
+			return true
+		}
+	}
+	return false
+}
+
+func FilterDebug(instr []ir.Instruction) []ir.Instruction {
+	var out []ir.Instruction
+	for _, ins := range instr {
+		if _, ok := ins.(*ir.DebugRef); !ok {
+			out = append(out, ins)
+		}
+	}
+	return out
+}
+
+func IsExample(fn *ir.Function) bool {
+	if !strings.HasPrefix(fn.Name(), "Example") {
+		return false
+	}
+	f := fn.Prog.Fset.File(fn.Pos())
+	if f == nil {
+		return false
+	}
+	return strings.HasSuffix(f.Name(), "_test.go")
+}
+
+// Flatten recursively returns the underlying value of an ir.Sigma or
+// ir.Phi node. If all edges in an ir.Phi node are the same (after
+// flattening), the flattened edge will get returned. If flattening is
+// not possible, nil is returned.
+func Flatten(v ir.Value) ir.Value {
+	failed := false
+	seen := map[ir.Value]struct{}{}
+	var out ir.Value
+	var dfs func(v ir.Value)
+	dfs = func(v ir.Value) {
+		if failed {
+			return
+		}
+		if _, ok := seen[v]; ok {
+			return
+		}
+		seen[v] = struct{}{}
+
+		switch v := v.(type) {
+		case *ir.Sigma:
+			dfs(v.X)
+		case *ir.Phi:
+			for _, e := range v.Edges {
+				dfs(e)
+			}
+		default:
+			if out == nil {
+				out = v
+			} else if out != v {
+				failed = true
+			}
+		}
+	}
+	dfs(v)
+
+	if failed {
+		return nil
+	}
+	return out
+}

vendor/honnef.co/go/tools/go/ir/irutil/visit.go

@@ -0,0 +1,79 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package irutil
+
+import "honnef.co/go/tools/go/ir"
+
+// This file defines utilities for visiting the IR of
+// a Program.
+//
+// TODO(adonovan): test coverage.
+
+// AllFunctions finds and returns the set of functions potentially
+// needed by program prog, as determined by a simple linker-style
+// reachability algorithm starting from the members and method-sets of
+// each package.  The result may include anonymous functions and
+// synthetic wrappers.
+//
+// Precondition: all packages are built.
+//
+func AllFunctions(prog *ir.Program) map[*ir.Function]bool {
+	visit := visitor{
+		prog: prog,
+		seen: make(map[*ir.Function]bool),
+	}
+	visit.program()
+	return visit.seen
+}
+
+type visitor struct {
+	prog *ir.Program
+	seen map[*ir.Function]bool
+}
+
+func (visit *visitor) program() {
+	for _, pkg := range visit.prog.AllPackages() {
+		for _, mem := range pkg.Members {
+			if fn, ok := mem.(*ir.Function); ok {
+				visit.function(fn)
+			}
+		}
+	}
+	for _, T := range visit.prog.RuntimeTypes() {
+		mset := visit.prog.MethodSets.MethodSet(T)
+		for i, n := 0, mset.Len(); i < n; i++ {
+			visit.function(visit.prog.MethodValue(mset.At(i)))
+		}
+	}
+}
+
+func (visit *visitor) function(fn *ir.Function) {
+	if !visit.seen[fn] {
+		visit.seen[fn] = true
+		var buf [10]*ir.Value // avoid alloc in common case
+		for _, b := range fn.Blocks {
+			for _, instr := range b.Instrs {
+				for _, op := range instr.Operands(buf[:0]) {
+					if fn, ok := (*op).(*ir.Function); ok {
+						visit.function(fn)
+					}
+				}
+			}
+		}
+	}
+}
+
+// MainPackages returns the subset of the specified packages
+// named "main" that define a main function.
+// The result may include synthetic "testmain" packages.
+func MainPackages(pkgs []*ir.Package) []*ir.Package {
+	var mains []*ir.Package
+	for _, pkg := range pkgs {
+		if pkg.Pkg.Name() == "main" && pkg.Func("main") != nil {
+			mains = append(mains, pkg)
+		}
+	}
+	return mains
+}

vendor/honnef.co/go/tools/go/ir/lvalue.go

@@ -0,0 +1,116 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// lvalues are the union of addressable expressions and map-index
+// expressions.
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+// An lvalue represents an assignable location that may appear on the
+// left-hand side of an assignment.  This is a generalization of a
+// pointer to permit updates to elements of maps.
+//
+type lvalue interface {
+	store(fn *Function, v Value, source ast.Node) // stores v into the location
+	load(fn *Function, source ast.Node) Value     // loads the contents of the location
+	address(fn *Function) Value                   // address of the location
+	typ() types.Type                              // returns the type of the location
+}
+
+// An address is an lvalue represented by a true pointer.
+type address struct {
+	addr Value
+	expr ast.Expr // source syntax of the value (not address) [debug mode]
+}
+
+func (a *address) load(fn *Function, source ast.Node) Value {
+	return emitLoad(fn, a.addr, source)
+}
+
+func (a *address) store(fn *Function, v Value, source ast.Node) {
+	store := emitStore(fn, a.addr, v, source)
+	if a.expr != nil {
+		// store.Val is v, converted for assignability.
+		emitDebugRef(fn, a.expr, store.Val, false)
+	}
+}
+
+func (a *address) address(fn *Function) Value {
+	if a.expr != nil {
+		emitDebugRef(fn, a.expr, a.addr, true)
+	}
+	return a.addr
+}
+
+func (a *address) typ() types.Type {
+	return deref(a.addr.Type())
+}
+
+// An element is an lvalue represented by m[k], the location of an
+// element of a map.  These locations are not addressable
+// since pointers cannot be formed from them, but they do support
+// load() and store().
+//
+type element struct {
+	m, k Value      // map
+	t    types.Type // map element type
+}
+
+func (e *element) load(fn *Function, source ast.Node) Value {
+	l := &MapLookup{
+		X:     e.m,
+		Index: e.k,
+	}
+	l.setType(e.t)
+	return fn.emit(l, source)
+}
+
+func (e *element) store(fn *Function, v Value, source ast.Node) {
+	up := &MapUpdate{
+		Map:   e.m,
+		Key:   e.k,
+		Value: emitConv(fn, v, e.t, source),
+	}
+	fn.emit(up, source)
+}
+
+func (e *element) address(fn *Function) Value {
+	panic("map elements are not addressable")
+}
+
+func (e *element) typ() types.Type {
+	return e.t
+}
+
+// A blank is a dummy variable whose name is "_".
+// It is not reified: loads are illegal and stores are ignored.
+//
+type blank struct{}
+
+func (bl blank) load(fn *Function, source ast.Node) Value {
+	panic("blank.load is illegal")
+}
+
+func (bl blank) store(fn *Function, v Value, source ast.Node) {
+	s := &BlankStore{
+		Val: v,
+	}
+	fn.emit(s, source)
+}
+
+func (bl blank) address(fn *Function) Value {
+	panic("blank var is not addressable")
+}
+
+func (bl blank) typ() types.Type {
+	// This should be the type of the blank Ident; the typechecker
+	// doesn't provide this yet, but fortunately, we don't need it
+	// yet either.
+	panic("blank.typ is unimplemented")
+}

vendor/honnef.co/go/tools/go/ir/methods.go

@@ -0,0 +1,248 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines utilities for population of method sets.
+
+import (
+	"fmt"
+	"go/types"
+
+	"honnef.co/go/tools/analysis/lint"
+
+	"golang.org/x/exp/typeparams"
+)
+
+// MethodValue returns the Function implementing method sel, building
+// wrapper methods on demand.  It returns nil if sel denotes an
+// abstract (interface) method.
+//
+// Precondition: sel.Kind() == MethodVal.
+//
+// Thread-safe.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) MethodValue(sel *types.Selection) *Function {
+	if sel.Kind() != types.MethodVal {
+		panic(fmt.Sprintf("MethodValue(%s) kind != MethodVal", sel))
+	}
+	T := sel.Recv()
+	if isInterface(T) {
+		return nil // abstract method
+	}
+	if prog.mode&LogSource != 0 {
+		defer logStack("MethodValue %s %v", T, sel)()
+	}
+
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	return prog.addMethod(prog.createMethodSet(T), sel)
+}
+
+// LookupMethod returns the implementation of the method of type T
+// identified by (pkg, name).  It returns nil if the method exists but
+// is abstract, and panics if T has no such method.
+//
+func (prog *Program) LookupMethod(T types.Type, pkg *types.Package, name string) *Function {
+	sel := prog.MethodSets.MethodSet(T).Lookup(pkg, name)
+	if sel == nil {
+		panic(fmt.Sprintf("%s has no method %s", T, types.Id(pkg, name)))
+	}
+	return prog.MethodValue(sel)
+}
+
+// methodSet contains the (concrete) methods of a non-interface type.
+type methodSet struct {
+	mapping  map[string]*Function // populated lazily
+	complete bool                 // mapping contains all methods
+}
+
+// Precondition: !isInterface(T).
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+func (prog *Program) createMethodSet(T types.Type) *methodSet {
+	mset, ok := prog.methodSets.At(T).(*methodSet)
+	if !ok {
+		mset = &methodSet{mapping: make(map[string]*Function)}
+		prog.methodSets.Set(T, mset)
+	}
+	return mset
+}
+
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+func (prog *Program) addMethod(mset *methodSet, sel *types.Selection) *Function {
+	if sel.Kind() == types.MethodExpr {
+		panic(sel)
+	}
+	id := sel.Obj().Id()
+	fn := mset.mapping[id]
+	if fn == nil {
+		obj := sel.Obj().(*types.Func)
+
+		needsPromotion := len(sel.Index()) > 1
+		needsIndirection := !isPointer(recvType(obj)) && isPointer(sel.Recv())
+		if needsPromotion || needsIndirection {
+			fn = makeWrapper(prog, sel)
+		} else {
+			fn = prog.declaredFunc(obj)
+		}
+		if fn.Signature.Recv() == nil {
+			panic(fn) // missing receiver
+		}
+		mset.mapping[id] = fn
+	}
+	return fn
+}
+
+// RuntimeTypes returns a new unordered slice containing all
+// concrete types in the program for which a complete (non-empty)
+// method set is required at run-time.
+//
+// Thread-safe.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) RuntimeTypes() []types.Type {
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	var res []types.Type
+	prog.methodSets.Iterate(func(T types.Type, v interface{}) {
+		if v.(*methodSet).complete {
+			res = append(res, T)
+		}
+	})
+	return res
+}
+
+// declaredFunc returns the concrete function/method denoted by obj.
+// Panic ensues if there is none.
+func (prog *Program) declaredFunc(obj *types.Func) *Function {
+	if origin := typeparams.OriginMethod(obj); origin != obj {
+		// Calling method on instantiated type, create a wrapper that calls the generic type's method
+		base := prog.packageLevelValue(origin)
+		return makeInstance(prog, base.(*Function), obj.Type().(*types.Signature), nil)
+	} else {
+		if v := prog.packageLevelValue(obj); v != nil {
+			return v.(*Function)
+		}
+	}
+	panic("no concrete method: " + obj.String())
+}
+
+// needMethodsOf ensures that runtime type information (including the
+// complete method set) is available for the specified type T and all
+// its subcomponents.
+//
+// needMethodsOf must be called for at least every type that is an
+// operand of some MakeInterface instruction, and for the type of
+// every exported package member.
+//
+// Precondition: T is not a method signature (*Signature with Recv()!=nil).
+//
+// Thread-safe.  (Called via emitConv from multiple builder goroutines.)
+//
+// TODO(adonovan): make this faster.  It accounts for 20% of SSA build time.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) needMethodsOf(T types.Type) {
+	prog.methodsMu.Lock()
+	prog.needMethods(T, false)
+	prog.methodsMu.Unlock()
+}
+
+// Precondition: T is not a method signature (*Signature with Recv()!=nil).
+// Recursive case: skip => don't create methods for T.
+//
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+//
+func (prog *Program) needMethods(T types.Type, skip bool) {
+	// Each package maintains its own set of types it has visited.
+	if prevSkip, ok := prog.runtimeTypes.At(T).(bool); ok {
+		// needMethods(T) was previously called
+		if !prevSkip || skip {
+			return // already seen, with same or false 'skip' value
+		}
+	}
+	prog.runtimeTypes.Set(T, skip)
+
+	tmset := prog.MethodSets.MethodSet(T)
+
+	if !skip && !isInterface(T) && tmset.Len() > 0 {
+		// Create methods of T.
+		mset := prog.createMethodSet(T)
+		if !mset.complete {
+			mset.complete = true
+			n := tmset.Len()
+			for i := 0; i < n; i++ {
+				prog.addMethod(mset, tmset.At(i))
+			}
+		}
+	}
+
+	// Recursion over signatures of each method.
+	for i := 0; i < tmset.Len(); i++ {
+		sig := tmset.At(i).Type().(*types.Signature)
+		prog.needMethods(sig.Params(), false)
+		prog.needMethods(sig.Results(), false)
+	}
+
+	switch t := T.(type) {
+	case *types.Basic:
+		// nop
+
+	case *types.Interface, *typeparams.TypeParam:
+		// nop---handled by recursion over method set.
+
+	case *types.Pointer:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Slice:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Chan:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Map:
+		prog.needMethods(t.Key(), false)
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Signature:
+		if t.Recv() != nil {
+			panic(fmt.Sprintf("Signature %s has Recv %s", t, t.Recv()))
+		}
+		prog.needMethods(t.Params(), false)
+		prog.needMethods(t.Results(), false)
+
+	case *types.Named:
+		// A pointer-to-named type can be derived from a named
+		// type via reflection.  It may have methods too.
+		prog.needMethods(types.NewPointer(t), false)
+
+		// Consider 'type T struct{S}' where S has methods.
+		// Reflection provides no way to get from T to struct{S},
+		// only to S, so the method set of struct{S} is unwanted,
+		// so set 'skip' flag during recursion.
+		prog.needMethods(t.Underlying(), true)
+
+	case *types.Array:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Struct:
+		for i, n := 0, t.NumFields(); i < n; i++ {
+			prog.needMethods(t.Field(i).Type(), false)
+		}
+
+	case *types.Tuple:
+		for i, n := 0, t.Len(); i < n; i++ {
+			prog.needMethods(t.At(i).Type(), false)
+		}
+
+	default:
+		lint.ExhaustiveTypeSwitch(T)
+	}
+}

vendor/honnef.co/go/tools/go/ir/mode.go

@@ -0,0 +1,105 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines the BuilderMode type and its command-line flag.
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// BuilderMode is a bitmask of options for diagnostics and checking.
+//
+// *BuilderMode satisfies the flag.Value interface.  Example:
+//
+// 	var mode = ir.BuilderMode(0)
+// 	func init() { flag.Var(&mode, "build", ir.BuilderModeDoc) }
+//
+type BuilderMode uint
+
+const (
+	PrintPackages            BuilderMode = 1 << iota // Print package inventory to stdout
+	PrintFunctions                                   // Print function IR code to stdout
+	PrintSource                                      // Print source code when printing function IR
+	LogSource                                        // Log source locations as IR builder progresses
+	SanityCheckFunctions                             // Perform sanity checking of function bodies
+	NaiveForm                                        // Build naïve IR form: don't replace local loads/stores with registers
+	GlobalDebug                                      // Enable debug info for all packages
+	SplitAfterNewInformation                         // Split live range after we learn something new about a value
+)
+
+const BuilderModeDoc = `Options controlling the IR builder.
+The value is a sequence of zero or more of these symbols:
+C	perform sanity [C]hecking of the IR form.
+D	include [D]ebug info for every function.
+P	print [P]ackage inventory.
+F	print [F]unction IR code.
+A	print [A]ST nodes responsible for IR instructions
+S	log [S]ource locations as IR builder progresses.
+N	build [N]aive IR form: don't replace local loads/stores with registers.
+I	Split live range after a value is used as slice or array index
+`
+
+func (m BuilderMode) String() string {
+	var buf bytes.Buffer
+	if m&GlobalDebug != 0 {
+		buf.WriteByte('D')
+	}
+	if m&PrintPackages != 0 {
+		buf.WriteByte('P')
+	}
+	if m&PrintFunctions != 0 {
+		buf.WriteByte('F')
+	}
+	if m&PrintSource != 0 {
+		buf.WriteByte('A')
+	}
+	if m&LogSource != 0 {
+		buf.WriteByte('S')
+	}
+	if m&SanityCheckFunctions != 0 {
+		buf.WriteByte('C')
+	}
+	if m&NaiveForm != 0 {
+		buf.WriteByte('N')
+	}
+	if m&SplitAfterNewInformation != 0 {
+		buf.WriteByte('I')
+	}
+	return buf.String()
+}
+
+// Set parses the flag characters in s and updates *m.
+func (m *BuilderMode) Set(s string) error {
+	var mode BuilderMode
+	for _, c := range s {
+		switch c {
+		case 'D':
+			mode |= GlobalDebug
+		case 'P':
+			mode |= PrintPackages
+		case 'F':
+			mode |= PrintFunctions
+		case 'A':
+			mode |= PrintSource
+		case 'S':
+			mode |= LogSource
+		case 'C':
+			mode |= SanityCheckFunctions
+		case 'N':
+			mode |= NaiveForm
+		case 'I':
+			mode |= SplitAfterNewInformation
+		default:
+			return fmt.Errorf("unknown BuilderMode option: %q", c)
+		}
+	}
+	*m = mode
+	return nil
+}
+
+// Get returns m.
+func (m BuilderMode) Get() interface{} { return m }

vendor/honnef.co/go/tools/go/ir/print.go

@@ -0,0 +1,482 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file implements the String() methods for all Value and
+// Instruction types.
+
+import (
+	"bytes"
+	"fmt"
+	"go/types"
+	"io"
+	"reflect"
+	"sort"
+
+	"honnef.co/go/tools/go/types/typeutil"
+)
+
+// relName returns the name of v relative to i.
+// In most cases, this is identical to v.Name(), but references to
+// Functions (including methods) and Globals use RelString and
+// all types are displayed with relType, so that only cross-package
+// references are package-qualified.
+//
+func relName(v Value, i Instruction) string {
+	if v == nil {
+		return "<nil>"
+	}
+	var from *types.Package
+	if i != nil {
+		from = i.Parent().pkg()
+	}
+	switch v := v.(type) {
+	case Member: // *Function or *Global
+		return v.RelString(from)
+	}
+	return v.Name()
+}
+
+func relType(t types.Type, from *types.Package) string {
+	return types.TypeString(t, types.RelativeTo(from))
+}
+
+func relString(m Member, from *types.Package) string {
+	// NB: not all globals have an Object (e.g. init$guard),
+	// so use Package().Object not Object.Package().
+	if pkg := m.Package().Pkg; pkg != nil && pkg != from {
+		return fmt.Sprintf("%s.%s", pkg.Path(), m.Name())
+	}
+	return m.Name()
+}
+
+// Value.String()
+//
+// This method is provided only for debugging.
+// It never appears in disassembly, which uses Value.Name().
+
+func (v *Parameter) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Parameter <%s> {%s}", relType(v.Type(), from), v.name)
+}
+
+func (v *FreeVar) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("FreeVar <%s> %s", relType(v.Type(), from), v.Name())
+}
+
+func (v *Builtin) String() string {
+	return fmt.Sprintf("Builtin %s", v.Name())
+}
+
+// Instruction.String()
+
+func (v *Alloc) String() string {
+	from := v.Parent().pkg()
+	storage := "Stack"
+	if v.Heap {
+		storage = "Heap"
+	}
+	return fmt.Sprintf("%sAlloc <%s>", storage, relType(v.Type(), from))
+}
+
+func (v *Sigma) String() string {
+	from := v.Parent().pkg()
+	s := fmt.Sprintf("Sigma <%s> [b%d] %s", relType(v.Type(), from), v.From.Index, v.X.Name())
+	return s
+}
+
+func (v *Phi) String() string {
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "Phi <%s>", v.Type())
+	for i, edge := range v.Edges {
+		b.WriteString(" ")
+		// Be robust against malformed CFG.
+		if v.block == nil {
+			b.WriteString("??")
+			continue
+		}
+		block := -1
+		if i < len(v.block.Preds) {
+			block = v.block.Preds[i].Index
+		}
+		fmt.Fprintf(&b, "%d:", block)
+		edgeVal := "<nil>" // be robust
+		if edge != nil {
+			edgeVal = relName(edge, v)
+		}
+		b.WriteString(edgeVal)
+	}
+	return b.String()
+}
+
+func printCall(v *CallCommon, prefix string, instr Instruction) string {
+	var b bytes.Buffer
+	if !v.IsInvoke() {
+		if value, ok := instr.(Value); ok {
+			fmt.Fprintf(&b, "%s <%s> %s", prefix, relType(value.Type(), instr.Parent().pkg()), relName(v.Value, instr))
+		} else {
+			fmt.Fprintf(&b, "%s %s", prefix, relName(v.Value, instr))
+		}
+	} else {
+		if value, ok := instr.(Value); ok {
+			fmt.Fprintf(&b, "%sInvoke <%s> %s.%s", prefix, relType(value.Type(), instr.Parent().pkg()), relName(v.Value, instr), v.Method.Name())
+		} else {
+			fmt.Fprintf(&b, "%sInvoke %s.%s", prefix, relName(v.Value, instr), v.Method.Name())
+		}
+	}
+	for _, arg := range v.TypeArgs {
+		b.WriteString(" ")
+		b.WriteString(relType(arg, instr.Parent().pkg()))
+	}
+	for _, arg := range v.Args {
+		b.WriteString(" ")
+		b.WriteString(relName(arg, instr))
+	}
+	return b.String()
+}
+
+func (c *CallCommon) String() string {
+	return printCall(c, "", nil)
+}
+
+func (v *Call) String() string {
+	return printCall(&v.Call, "Call", v)
+}
+
+func (v *BinOp) String() string {
+	return fmt.Sprintf("BinOp <%s> {%s} %s %s", relType(v.Type(), v.Parent().pkg()), v.Op.String(), relName(v.X, v), relName(v.Y, v))
+}
+
+func (v *UnOp) String() string {
+	return fmt.Sprintf("UnOp <%s> {%s} %s", relType(v.Type(), v.Parent().pkg()), v.Op.String(), relName(v.X, v))
+}
+
+func (v *Load) String() string {
+	return fmt.Sprintf("Load <%s> %s", relType(v.Type(), v.Parent().pkg()), relName(v.X, v))
+}
+
+func (v *Copy) String() string {
+	return fmt.Sprintf("Copy <%s> %s", relType(v.Type(), v.Parent().pkg()), relName(v.X, v))
+}
+
+func printConv(prefix string, v, x Value) string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("%s <%s> %s",
+		prefix,
+		relType(v.Type(), from),
+		relName(x, v.(Instruction)))
+}
+
+func (v *ChangeType) String() string          { return printConv("ChangeType", v, v.X) }
+func (v *Convert) String() string             { return printConv("Convert", v, v.X) }
+func (v *ChangeInterface) String() string     { return printConv("ChangeInterface", v, v.X) }
+func (v *SliceToArrayPointer) String() string { return printConv("SliceToArrayPointer", v, v.X) }
+func (v *MakeInterface) String() string       { return printConv("MakeInterface", v, v.X) }
+
+func (v *MakeClosure) String() string {
+	from := v.Parent().pkg()
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "MakeClosure <%s> %s", relType(v.Type(), from), relName(v.Fn, v))
+	if v.Bindings != nil {
+		for _, c := range v.Bindings {
+			b.WriteString(" ")
+			b.WriteString(relName(c, v))
+		}
+	}
+	return b.String()
+}
+
+func (v *MakeSlice) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("MakeSlice <%s> %s %s",
+		relType(v.Type(), from),
+		relName(v.Len, v),
+		relName(v.Cap, v))
+}
+
+func (v *Slice) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Slice <%s> %s %s %s %s",
+		relType(v.Type(), from), relName(v.X, v), relName(v.Low, v), relName(v.High, v), relName(v.Max, v))
+}
+
+func (v *MakeMap) String() string {
+	res := ""
+	if v.Reserve != nil {
+		res = relName(v.Reserve, v)
+	}
+	from := v.Parent().pkg()
+	return fmt.Sprintf("MakeMap <%s> %s", relType(v.Type(), from), res)
+}
+
+func (v *MakeChan) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("MakeChan <%s> %s", relType(v.Type(), from), relName(v.Size, v))
+}
+
+func (v *FieldAddr) String() string {
+	from := v.Parent().pkg()
+	// v.X.Type() might be a pointer to a type parameter whose core type is a pointer to a struct
+	st := deref(typeutil.CoreType(deref(v.X.Type()))).Underlying().(*types.Struct)
+	// Be robust against a bad index.
+	name := "?"
+	if 0 <= v.Field && v.Field < st.NumFields() {
+		name = st.Field(v.Field).Name()
+	}
+	return fmt.Sprintf("FieldAddr <%s> [%d] (%s) %s", relType(v.Type(), from), v.Field, name, relName(v.X, v))
+}
+
+func (v *Field) String() string {
+	st := typeutil.CoreType(v.X.Type()).Underlying().(*types.Struct)
+	// Be robust against a bad index.
+	name := "?"
+	if 0 <= v.Field && v.Field < st.NumFields() {
+		name = st.Field(v.Field).Name()
+	}
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Field <%s> [%d] (%s) %s", relType(v.Type(), from), v.Field, name, relName(v.X, v))
+}
+
+func (v *IndexAddr) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("IndexAddr <%s> %s %s", relType(v.Type(), from), relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *Index) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Index <%s> %s %s", relType(v.Type(), from), relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *MapLookup) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("MapLookup <%s> %s %s", relType(v.Type(), from), relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *StringLookup) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("StringLookup <%s> %s %s", relType(v.Type(), from), relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *Range) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Range <%s> %s", relType(v.Type(), from), relName(v.X, v))
+}
+
+func (v *Next) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("Next <%s> %s", relType(v.Type(), from), relName(v.Iter, v))
+}
+
+func (v *TypeAssert) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("TypeAssert <%s> %s", relType(v.Type(), from), relName(v.X, v))
+}
+
+func (v *Extract) String() string {
+	from := v.Parent().pkg()
+	name := v.Tuple.Type().(*types.Tuple).At(v.Index).Name()
+	return fmt.Sprintf("Extract <%s> [%d] (%s) %s", relType(v.Type(), from), v.Index, name, relName(v.Tuple, v))
+}
+
+func (s *Jump) String() string {
+	// Be robust against malformed CFG.
+	block := -1
+	if s.block != nil && len(s.block.Succs) == 1 {
+		block = s.block.Succs[0].Index
+	}
+	str := fmt.Sprintf("Jump → b%d", block)
+	if s.Comment != "" {
+		str = fmt.Sprintf("%s # %s", str, s.Comment)
+	}
+	return str
+}
+
+func (s *Unreachable) String() string {
+	// Be robust against malformed CFG.
+	block := -1
+	if s.block != nil && len(s.block.Succs) == 1 {
+		block = s.block.Succs[0].Index
+	}
+	return fmt.Sprintf("Unreachable → b%d", block)
+}
+
+func (s *If) String() string {
+	// Be robust against malformed CFG.
+	tblock, fblock := -1, -1
+	if s.block != nil && len(s.block.Succs) == 2 {
+		tblock = s.block.Succs[0].Index
+		fblock = s.block.Succs[1].Index
+	}
+	return fmt.Sprintf("If %s → b%d b%d", relName(s.Cond, s), tblock, fblock)
+}
+
+func (s *ConstantSwitch) String() string {
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "ConstantSwitch %s", relName(s.Tag, s))
+	for _, cond := range s.Conds {
+		fmt.Fprintf(&b, " %s", relName(cond, s))
+	}
+	fmt.Fprint(&b, " →")
+	for _, succ := range s.block.Succs {
+		fmt.Fprintf(&b, " b%d", succ.Index)
+	}
+	return b.String()
+}
+
+func (s *TypeSwitch) String() string {
+	from := s.Parent().pkg()
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "TypeSwitch <%s> %s", relType(s.typ, from), relName(s.Tag, s))
+	for _, cond := range s.Conds {
+		fmt.Fprintf(&b, " %q", relType(cond, s.block.parent.pkg()))
+	}
+	return b.String()
+}
+
+func (s *Go) String() string {
+	return printCall(&s.Call, "Go", s)
+}
+
+func (s *Panic) String() string {
+	// Be robust against malformed CFG.
+	block := -1
+	if s.block != nil && len(s.block.Succs) == 1 {
+		block = s.block.Succs[0].Index
+	}
+	return fmt.Sprintf("Panic %s → b%d", relName(s.X, s), block)
+}
+
+func (s *Return) String() string {
+	var b bytes.Buffer
+	b.WriteString("Return")
+	for _, r := range s.Results {
+		b.WriteString(" ")
+		b.WriteString(relName(r, s))
+	}
+	return b.String()
+}
+
+func (*RunDefers) String() string {
+	return "RunDefers"
+}
+
+func (s *Send) String() string {
+	return fmt.Sprintf("Send %s %s", relName(s.Chan, s), relName(s.X, s))
+}
+
+func (recv *Recv) String() string {
+	from := recv.Parent().pkg()
+	return fmt.Sprintf("Recv <%s> %s", relType(recv.Type(), from), relName(recv.Chan, recv))
+}
+
+func (s *Defer) String() string {
+	return printCall(&s.Call, "Defer", s)
+}
+
+func (s *Select) String() string {
+	var b bytes.Buffer
+	for i, st := range s.States {
+		if i > 0 {
+			b.WriteString(", ")
+		}
+		if st.Dir == types.RecvOnly {
+			b.WriteString("<-")
+			b.WriteString(relName(st.Chan, s))
+		} else {
+			b.WriteString(relName(st.Chan, s))
+			b.WriteString("<-")
+			b.WriteString(relName(st.Send, s))
+		}
+	}
+	non := ""
+	if !s.Blocking {
+		non = "Non"
+	}
+	from := s.Parent().pkg()
+	return fmt.Sprintf("Select%sBlocking <%s> [%s]", non, relType(s.Type(), from), b.String())
+}
+
+func (s *Store) String() string {
+	return fmt.Sprintf("Store {%s} %s %s",
+		s.Val.Type(), relName(s.Addr, s), relName(s.Val, s))
+}
+
+func (s *BlankStore) String() string {
+	return fmt.Sprintf("BlankStore %s", relName(s.Val, s))
+}
+
+func (s *MapUpdate) String() string {
+	return fmt.Sprintf("MapUpdate %s %s %s", relName(s.Map, s), relName(s.Key, s), relName(s.Value, s))
+}
+
+func (s *DebugRef) String() string {
+	p := s.Parent().Prog.Fset.Position(s.Pos())
+	var descr interface{}
+	if s.object != nil {
+		descr = s.object // e.g. "var x int"
+	} else {
+		descr = reflect.TypeOf(s.Expr) // e.g. "*ast.CallExpr"
+	}
+	var addr string
+	if s.IsAddr {
+		addr = "address of "
+	}
+	return fmt.Sprintf("; %s%s @ %d:%d is %s", addr, descr, p.Line, p.Column, s.X.Name())
+}
+
+func (p *Package) String() string {
+	return "package " + p.Pkg.Path()
+}
+
+var _ io.WriterTo = (*Package)(nil) // *Package implements io.Writer
+
+func (p *Package) WriteTo(w io.Writer) (int64, error) {
+	var buf bytes.Buffer
+	WritePackage(&buf, p)
+	n, err := w.Write(buf.Bytes())
+	return int64(n), err
+}
+
+// WritePackage writes to buf a human-readable summary of p.
+func WritePackage(buf *bytes.Buffer, p *Package) {
+	fmt.Fprintf(buf, "%s:\n", p)
+
+	var names []string
+	maxname := 0
+	for name := range p.Members {
+		if l := len(name); l > maxname {
+			maxname = l
+		}
+		names = append(names, name)
+	}
+
+	from := p.Pkg
+	sort.Strings(names)
+	for _, name := range names {
+		switch mem := p.Members[name].(type) {
+		case *NamedConst:
+			fmt.Fprintf(buf, "  const %-*s %s = %s\n",
+				maxname, name, mem.Name(), mem.Value.RelString(from))
+
+		case *Function:
+			fmt.Fprintf(buf, "  func  %-*s %s\n",
+				maxname, name, relType(mem.Type(), from))
+
+		case *Type:
+			fmt.Fprintf(buf, "  type  %-*s %s\n",
+				maxname, name, relType(mem.Type().Underlying(), from))
+			for _, meth := range typeutil.IntuitiveMethodSet(mem.Type(), &p.Prog.MethodSets) {
+				fmt.Fprintf(buf, "    %s\n", types.SelectionString(meth, types.RelativeTo(from)))
+			}
+
+		case *Global:
+			fmt.Fprintf(buf, "  var   %-*s %s\n",
+				maxname, name, relType(mem.Type().(*types.Pointer).Elem(), from))
+		}
+	}
+
+	fmt.Fprintf(buf, "\n")
+}

vendor/honnef.co/go/tools/go/ir/sanity.go

@@ -0,0 +1,556 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// An optional pass for sanity-checking invariants of the IR representation.
+// Currently it checks CFG invariants but little at the instruction level.
+
+import (
+	"fmt"
+	"go/types"
+	"io"
+	"os"
+	"strings"
+)
+
+type sanity struct {
+	reporter io.Writer
+	fn       *Function
+	block    *BasicBlock
+	instrs   map[Instruction]struct{}
+	insane   bool
+}
+
+// sanityCheck performs integrity checking of the IR representation
+// of the function fn and returns true if it was valid.  Diagnostics
+// are written to reporter if non-nil, os.Stderr otherwise.  Some
+// diagnostics are only warnings and do not imply a negative result.
+//
+// Sanity-checking is intended to facilitate the debugging of code
+// transformation passes.
+//
+func sanityCheck(fn *Function, reporter io.Writer) bool {
+	if reporter == nil {
+		reporter = os.Stderr
+	}
+	return (&sanity{reporter: reporter}).checkFunction(fn)
+}
+
+// mustSanityCheck is like sanityCheck but panics instead of returning
+// a negative result.
+//
+func mustSanityCheck(fn *Function, reporter io.Writer) {
+	if !sanityCheck(fn, reporter) {
+		fn.WriteTo(os.Stderr)
+		panic("SanityCheck failed")
+	}
+}
+
+func (s *sanity) diagnostic(prefix, format string, args ...interface{}) {
+	fmt.Fprintf(s.reporter, "%s: function %s", prefix, s.fn)
+	if s.block != nil {
+		fmt.Fprintf(s.reporter, ", block %s", s.block)
+	}
+	io.WriteString(s.reporter, ": ")
+	fmt.Fprintf(s.reporter, format, args...)
+	io.WriteString(s.reporter, "\n")
+}
+
+func (s *sanity) errorf(format string, args ...interface{}) {
+	s.insane = true
+	s.diagnostic("Error", format, args...)
+}
+
+func (s *sanity) warnf(format string, args ...interface{}) {
+	s.diagnostic("Warning", format, args...)
+}
+
+// findDuplicate returns an arbitrary basic block that appeared more
+// than once in blocks, or nil if all were unique.
+func findDuplicate(blocks []*BasicBlock) *BasicBlock {
+	if len(blocks) < 2 {
+		return nil
+	}
+	if blocks[0] == blocks[1] {
+		return blocks[0]
+	}
+	// Slow path:
+	m := make(map[*BasicBlock]bool)
+	for _, b := range blocks {
+		if m[b] {
+			return b
+		}
+		m[b] = true
+	}
+	return nil
+}
+
+func (s *sanity) checkInstr(idx int, instr Instruction) {
+	switch instr := instr.(type) {
+	case *If, *Jump, *Return, *Panic, *Unreachable, *ConstantSwitch:
+		s.errorf("control flow instruction not at end of block")
+	case *Sigma:
+		if idx > 0 {
+			prev := s.block.Instrs[idx-1]
+			if _, ok := prev.(*Sigma); !ok {
+				s.errorf("Sigma instruction follows a non-Sigma: %T", prev)
+			}
+		}
+	case *Phi:
+		if idx == 0 {
+			// It suffices to apply this check to just the first phi node.
+			if dup := findDuplicate(s.block.Preds); dup != nil {
+				s.errorf("phi node in block with duplicate predecessor %s", dup)
+			}
+		} else {
+			prev := s.block.Instrs[idx-1]
+			switch prev.(type) {
+			case *Phi, *Sigma:
+			default:
+				s.errorf("Phi instruction follows a non-Phi, non-Sigma: %T", prev)
+			}
+		}
+		if ne, np := len(instr.Edges), len(s.block.Preds); ne != np {
+			s.errorf("phi node has %d edges but %d predecessors", ne, np)
+
+		} else {
+			for i, e := range instr.Edges {
+				if e == nil {
+					s.errorf("phi node '%v' has no value for edge #%d from %s", instr, i, s.block.Preds[i])
+				}
+			}
+		}
+
+	case *Alloc:
+		if !instr.Heap {
+			found := false
+			for _, l := range s.fn.Locals {
+				if l == instr {
+					found = true
+					break
+				}
+			}
+			if !found {
+				s.errorf("local alloc %s = %s does not appear in Function.Locals", instr.Name(), instr)
+			}
+		}
+
+	case *BinOp:
+	case *Call:
+	case *ChangeInterface:
+	case *ChangeType:
+	case *SliceToArrayPointer:
+	case *Convert:
+		if _, ok := instr.X.Type().Underlying().(*types.Basic); !ok {
+			if _, ok := instr.Type().Underlying().(*types.Basic); !ok {
+				s.errorf("convert %s -> %s: at least one type must be basic", instr.X.Type(), instr.Type())
+			}
+		}
+
+	case *Defer:
+	case *Extract:
+	case *Field:
+	case *FieldAddr:
+	case *Go:
+	case *Index:
+	case *IndexAddr:
+	case *MapLookup:
+	case *StringLookup:
+	case *MakeChan:
+	case *MakeClosure:
+		numFree := len(instr.Fn.(*Function).FreeVars)
+		numBind := len(instr.Bindings)
+		if numFree != numBind {
+			s.errorf("MakeClosure has %d Bindings for function %s with %d free vars",
+				numBind, instr.Fn, numFree)
+
+		}
+		if recv := instr.Type().(*types.Signature).Recv(); recv != nil {
+			s.errorf("MakeClosure's type includes receiver %s", recv.Type())
+		}
+
+	case *MakeInterface:
+	case *MakeMap:
+	case *MakeSlice:
+	case *MapUpdate:
+	case *Next:
+	case *Range:
+	case *RunDefers:
+	case *Select:
+	case *Send:
+	case *Slice:
+	case *Store:
+	case *TypeAssert:
+	case *UnOp:
+	case *DebugRef:
+	case *BlankStore:
+	case *Load:
+	case *Parameter:
+	case *Const:
+	case *AggregateConst:
+	case *ArrayConst:
+	case *GenericConst:
+	case *Recv:
+	case *TypeSwitch:
+	default:
+		panic(fmt.Sprintf("Unknown instruction type: %T", instr))
+	}
+
+	if call, ok := instr.(CallInstruction); ok {
+		if call.Common().Signature() == nil {
+			s.errorf("nil signature: %s", call)
+		}
+	}
+
+	// Check that value-defining instructions have valid types
+	// and a valid referrer list.
+	if v, ok := instr.(Value); ok {
+		t := v.Type()
+		if t == nil {
+			s.errorf("no type: %s = %s", v.Name(), v)
+		} else if b, ok := t.Underlying().(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
+			if _, ok := v.(*Const); !ok {
+				s.errorf("instruction has 'untyped' result: %s = %s : %s", v.Name(), v, t)
+			}
+		}
+		s.checkReferrerList(v)
+	}
+
+	// Untyped constants are legal as instruction Operands(),
+	// for example:
+	//   _ = "foo"[0]
+	// or:
+	//   if wordsize==64 {...}
+
+	// All other non-Instruction Values can be found via their
+	// enclosing Function or Package.
+}
+
+func (s *sanity) checkFinalInstr(instr Instruction) {
+	switch instr := instr.(type) {
+	case *If:
+		if nsuccs := len(s.block.Succs); nsuccs != 2 {
+			s.errorf("If-terminated block has %d successors; expected 2", nsuccs)
+			return
+		}
+		if s.block.Succs[0] == s.block.Succs[1] {
+			s.errorf("If-instruction has same True, False target blocks: %s", s.block.Succs[0])
+			return
+		}
+
+	case *Jump:
+		if nsuccs := len(s.block.Succs); nsuccs != 1 {
+			s.errorf("Jump-terminated block has %d successors; expected 1", nsuccs)
+			return
+		}
+
+	case *Return:
+		if nsuccs := len(s.block.Succs); nsuccs != 0 {
+			s.errorf("Return-terminated block has %d successors; expected none", nsuccs)
+			return
+		}
+		if na, nf := len(instr.Results), s.fn.Signature.Results().Len(); nf != na {
+			s.errorf("%d-ary return in %d-ary function", na, nf)
+		}
+
+	case *Panic:
+		if nsuccs := len(s.block.Succs); nsuccs != 1 {
+			s.errorf("Panic-terminated block has %d successors; expected one", nsuccs)
+			return
+		}
+
+	case *Unreachable:
+		if nsuccs := len(s.block.Succs); nsuccs != 1 {
+			s.errorf("Unreachable-terminated block has %d successors; expected one", nsuccs)
+			return
+		}
+
+	case *ConstantSwitch:
+
+	default:
+		s.errorf("non-control flow instruction at end of block")
+	}
+}
+
+func (s *sanity) checkBlock(b *BasicBlock, index int) {
+	s.block = b
+
+	if b.Index != index {
+		s.errorf("block has incorrect Index %d", b.Index)
+	}
+	if b.parent != s.fn {
+		s.errorf("block has incorrect parent %s", b.parent)
+	}
+
+	// Check all blocks are reachable.
+	// (The entry block is always implicitly reachable, the exit block may be unreachable.)
+	if index > 1 && len(b.Preds) == 0 {
+		s.warnf("unreachable block")
+		if b.Instrs == nil {
+			// Since this block is about to be pruned,
+			// tolerating transient problems in it
+			// simplifies other optimizations.
+			return
+		}
+	}
+
+	// Check predecessor and successor relations are dual,
+	// and that all blocks in CFG belong to same function.
+	for _, a := range b.Preds {
+		found := false
+		for _, bb := range a.Succs {
+			if bb == b {
+				found = true
+				break
+			}
+		}
+		if !found {
+			s.errorf("expected successor edge in predecessor %s; found only: %s", a, a.Succs)
+		}
+		if a.parent != s.fn {
+			s.errorf("predecessor %s belongs to different function %s", a, a.parent)
+		}
+	}
+	for _, c := range b.Succs {
+		found := false
+		for _, bb := range c.Preds {
+			if bb == b {
+				found = true
+				break
+			}
+		}
+		if !found {
+			s.errorf("expected predecessor edge in successor %s; found only: %s", c, c.Preds)
+		}
+		if c.parent != s.fn {
+			s.errorf("successor %s belongs to different function %s", c, c.parent)
+		}
+	}
+
+	// Check each instruction is sane.
+	n := len(b.Instrs)
+	if n == 0 {
+		s.errorf("basic block contains no instructions")
+	}
+	var rands [10]*Value // reuse storage
+	for j, instr := range b.Instrs {
+		if instr == nil {
+			s.errorf("nil instruction at index %d", j)
+			continue
+		}
+		if b2 := instr.Block(); b2 == nil {
+			s.errorf("nil Block() for instruction at index %d", j)
+			continue
+		} else if b2 != b {
+			s.errorf("wrong Block() (%s) for instruction at index %d ", b2, j)
+			continue
+		}
+		if j < n-1 {
+			s.checkInstr(j, instr)
+		} else {
+			s.checkFinalInstr(instr)
+		}
+
+		// Check Instruction.Operands.
+	operands:
+		for i, op := range instr.Operands(rands[:0]) {
+			if op == nil {
+				s.errorf("nil operand pointer %d of %s", i, instr)
+				continue
+			}
+			val := *op
+			if val == nil {
+				continue // a nil operand is ok
+			}
+
+			// Check that "untyped" types only appear on constant operands.
+			if _, ok := (*op).(*Const); !ok {
+				if basic, ok := (*op).Type().(*types.Basic); ok {
+					if basic.Info()&types.IsUntyped != 0 {
+						s.errorf("operand #%d of %s is untyped: %s", i, instr, basic)
+					}
+				}
+			}
+
+			// Check that Operands that are also Instructions belong to same function.
+			// TODO(adonovan): also check their block dominates block b.
+			if val, ok := val.(Instruction); ok {
+				if val.Block() == nil {
+					s.errorf("operand %d of %s is an instruction (%s) that belongs to no block", i, instr, val)
+				} else if val.Parent() != s.fn {
+					s.errorf("operand %d of %s is an instruction (%s) from function %s", i, instr, val, val.Parent())
+				}
+			}
+
+			// Check that each function-local operand of
+			// instr refers back to instr.  (NB: quadratic)
+			switch val := val.(type) {
+			case *Const, *Global, *Builtin:
+				continue // not local
+			case *Function:
+				if val.parent == nil {
+					continue // only anon functions are local
+				}
+			}
+
+			// TODO(adonovan): check val.Parent() != nil <=> val.Referrers() is defined.
+
+			if refs := val.Referrers(); refs != nil {
+				for _, ref := range *refs {
+					if ref == instr {
+						continue operands
+					}
+				}
+				s.errorf("operand %d of %s (%s) does not refer to us", i, instr, val)
+			} else {
+				s.errorf("operand %d of %s (%s) has no referrers", i, instr, val)
+			}
+		}
+	}
+}
+
+func (s *sanity) checkReferrerList(v Value) {
+	refs := v.Referrers()
+	if refs == nil {
+		s.errorf("%s has missing referrer list", v.Name())
+		return
+	}
+	for i, ref := range *refs {
+		if _, ok := s.instrs[ref]; !ok {
+			if val, ok := ref.(Value); ok {
+				s.errorf("%s.Referrers()[%d] = %s = %s is not an instruction belonging to this function", v.Name(), i, val.Name(), val)
+			} else {
+				s.errorf("%s.Referrers()[%d] = %s is not an instruction belonging to this function", v.Name(), i, ref)
+			}
+		}
+	}
+}
+
+func (s *sanity) checkFunction(fn *Function) bool {
+	// TODO(adonovan): check Function invariants:
+	// - check params match signature
+	// - check transient fields are nil
+	// - warn if any fn.Locals do not appear among block instructions.
+	s.fn = fn
+	if fn.Prog == nil {
+		s.errorf("nil Prog")
+	}
+
+	_ = fn.String()            // must not crash
+	_ = fn.RelString(fn.pkg()) // must not crash
+
+	// All functions have a package, except delegates (which are
+	// shared across packages, or duplicated as weak symbols in a
+	// separate-compilation model), and error.Error.
+	if fn.Pkg == nil {
+		switch fn.Synthetic {
+		case SyntheticWrapper, SyntheticBound, SyntheticThunk, SyntheticGeneric:
+		default:
+			if !strings.HasSuffix(fn.name, "Error") {
+				s.errorf("nil Pkg")
+			}
+		}
+	}
+	if src, syn := fn.Synthetic == 0, fn.source != nil; src != syn {
+		s.errorf("got fromSource=%t, hasSyntax=%t; want same values", src, syn)
+	}
+	for i, l := range fn.Locals {
+		if l.Parent() != fn {
+			s.errorf("Local %s at index %d has wrong parent", l.Name(), i)
+		}
+		if l.Heap {
+			s.errorf("Local %s at index %d has Heap flag set", l.Name(), i)
+		}
+	}
+	// Build the set of valid referrers.
+	s.instrs = make(map[Instruction]struct{})
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			s.instrs[instr] = struct{}{}
+		}
+	}
+	for i, p := range fn.Params {
+		if p.Parent() != fn {
+			s.errorf("Param %s at index %d has wrong parent", p.Name(), i)
+		}
+		// Check common suffix of Signature and Params match type.
+		if sig := fn.Signature; sig != nil {
+			j := i - len(fn.Params) + sig.Params().Len() // index within sig.Params
+			if j < 0 {
+				continue
+			}
+			if !types.Identical(p.Type(), sig.Params().At(j).Type()) {
+				s.errorf("Param %s at index %d has wrong type (%s, versus %s in Signature)", p.Name(), i, p.Type(), sig.Params().At(j).Type())
+
+			}
+		}
+
+		s.checkReferrerList(p)
+	}
+	for i, fv := range fn.FreeVars {
+		if fv.Parent() != fn {
+			s.errorf("FreeVar %s at index %d has wrong parent", fv.Name(), i)
+		}
+		s.checkReferrerList(fv)
+	}
+
+	if fn.Blocks != nil && len(fn.Blocks) == 0 {
+		// Function _had_ blocks (so it's not external) but
+		// they were "optimized" away, even the entry block.
+		s.errorf("Blocks slice is non-nil but empty")
+	}
+	for i, b := range fn.Blocks {
+		if b == nil {
+			s.warnf("nil *BasicBlock at f.Blocks[%d]", i)
+			continue
+		}
+		s.checkBlock(b, i)
+	}
+
+	s.block = nil
+	for i, anon := range fn.AnonFuncs {
+		if anon.Parent() != fn {
+			s.errorf("AnonFuncs[%d]=%s but %s.Parent()=%s", i, anon, anon, anon.Parent())
+		}
+	}
+	s.fn = nil
+	return !s.insane
+}
+
+// sanityCheckPackage checks invariants of packages upon creation.
+// It does not require that the package is built.
+// Unlike sanityCheck (for functions), it just panics at the first error.
+func sanityCheckPackage(pkg *Package) {
+	if pkg.Pkg == nil {
+		panic(fmt.Sprintf("Package %s has no Object", pkg))
+	}
+	_ = pkg.String() // must not crash
+
+	for name, mem := range pkg.Members {
+		if name != mem.Name() {
+			panic(fmt.Sprintf("%s: %T.Name() = %s, want %s",
+				pkg.Pkg.Path(), mem, mem.Name(), name))
+		}
+		obj := mem.Object()
+		if obj == nil {
+			// This check is sound because fields
+			// {Global,Function}.object have type
+			// types.Object.  (If they were declared as
+			// *types.{Var,Func}, we'd have a non-empty
+			// interface containing a nil pointer.)
+
+			continue // not all members have typechecker objects
+		}
+		if obj.Name() != name {
+			if obj.Name() == "init" && strings.HasPrefix(mem.Name(), "init#") {
+				// Ok.  The name of a declared init function varies between
+				// its types.Func ("init") and its ir.Function ("init#%d").
+			} else {
+				panic(fmt.Sprintf("%s: %T.Object().Name() = %s, want %s",
+					pkg.Pkg.Path(), mem, obj.Name(), name))
+			}
+		}
+	}
+}

vendor/honnef.co/go/tools/go/ir/source.go

@@ -0,0 +1,273 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines utilities for working with source positions
+// or source-level named entities ("objects").
+
+// TODO(adonovan): test that {Value,Instruction}.Pos() positions match
+// the originating syntax, as specified.
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/exp/typeparams"
+)
+
+// EnclosingFunction returns the function that contains the syntax
+// node denoted by path.
+//
+// Syntax associated with package-level variable specifications is
+// enclosed by the package's init() function.
+//
+// Returns nil if not found; reasons might include:
+//    - the node is not enclosed by any function.
+//    - the node is within an anonymous function (FuncLit) and
+//      its IR function has not been created yet
+//      (pkg.Build() has not yet been called).
+//
+func EnclosingFunction(pkg *Package, path []ast.Node) *Function {
+	// Start with package-level function...
+	fn := findEnclosingPackageLevelFunction(pkg, path)
+	if fn == nil {
+		return nil // not in any function
+	}
+
+	// ...then walk down the nested anonymous functions.
+	n := len(path)
+outer:
+	for i := range path {
+		if lit, ok := path[n-1-i].(*ast.FuncLit); ok {
+			for _, anon := range fn.AnonFuncs {
+				if anon.Pos() == lit.Type.Func {
+					fn = anon
+					continue outer
+				}
+			}
+			// IR function not found:
+			// - package not yet built, or maybe
+			// - builder skipped FuncLit in dead block
+			//   (in principle; but currently the Builder
+			//   generates even dead FuncLits).
+			return nil
+		}
+	}
+	return fn
+}
+
+// HasEnclosingFunction returns true if the AST node denoted by path
+// is contained within the declaration of some function or
+// package-level variable.
+//
+// Unlike EnclosingFunction, the behaviour of this function does not
+// depend on whether IR code for pkg has been built, so it can be
+// used to quickly reject check inputs that will cause
+// EnclosingFunction to fail, prior to IR building.
+//
+func HasEnclosingFunction(pkg *Package, path []ast.Node) bool {
+	return findEnclosingPackageLevelFunction(pkg, path) != nil
+}
+
+// findEnclosingPackageLevelFunction returns the Function
+// corresponding to the package-level function enclosing path.
+//
+func findEnclosingPackageLevelFunction(pkg *Package, path []ast.Node) *Function {
+	if n := len(path); n >= 2 { // [... {Gen,Func}Decl File]
+		switch decl := path[n-2].(type) {
+		case *ast.GenDecl:
+			if decl.Tok == token.VAR && n >= 3 {
+				// Package-level 'var' initializer.
+				return pkg.init
+			}
+
+		case *ast.FuncDecl:
+			// Declared function/method.
+			fn := findNamedFunc(pkg, decl.Pos())
+			if fn == nil && decl.Recv == nil && decl.Name.Name == "init" {
+				// Hack: return non-nil when IR is not yet
+				// built so that HasEnclosingFunction works.
+				return pkg.init
+			}
+			return fn
+		}
+	}
+	return nil // not in any function
+}
+
+// findNamedFunc returns the named function whose FuncDecl.Ident is at
+// position pos.
+//
+func findNamedFunc(pkg *Package, pos token.Pos) *Function {
+	for _, fn := range pkg.Functions {
+		if fn.Pos() == pos {
+			return fn
+		}
+	}
+	return nil
+}
+
+// ValueForExpr returns the IR Value that corresponds to non-constant
+// expression e.
+//
+// It returns nil if no value was found, e.g.
+//    - the expression is not lexically contained within f;
+//    - f was not built with debug information; or
+//    - e is a constant expression.  (For efficiency, no debug
+//      information is stored for constants. Use
+//      go/types.Info.Types[e].Value instead.)
+//    - e is a reference to nil or a built-in function.
+//    - the value was optimised away.
+//
+// If e is an addressable expression used in an lvalue context,
+// value is the address denoted by e, and isAddr is true.
+//
+// The types of e (or &e, if isAddr) and the result are equal
+// (modulo "untyped" bools resulting from comparisons).
+//
+// (Tip: to find the ir.Value given a source position, use
+// astutil.PathEnclosingInterval to locate the ast.Node, then
+// EnclosingFunction to locate the Function, then ValueForExpr to find
+// the ir.Value.)
+//
+func (f *Function) ValueForExpr(e ast.Expr) (value Value, isAddr bool) {
+	if f.debugInfo() { // (opt)
+		e = unparen(e)
+		for _, b := range f.Blocks {
+			for _, instr := range b.Instrs {
+				if ref, ok := instr.(*DebugRef); ok {
+					if ref.Expr == e {
+						return ref.X, ref.IsAddr
+					}
+				}
+			}
+		}
+	}
+	return
+}
+
+// --- Lookup functions for source-level named entities (types.Objects) ---
+
+// Package returns the IR Package corresponding to the specified
+// type-checker package object.
+// It returns nil if no such IR package has been created.
+//
+func (prog *Program) Package(obj *types.Package) *Package {
+	return prog.packages[obj]
+}
+
+// packageLevelValue returns the package-level value corresponding to
+// the specified named object, which may be a package-level const
+// (*Const), var (*Global) or func (*Function) of some package in
+// prog.  It returns nil if the object is not found.
+//
+func (prog *Program) packageLevelValue(obj types.Object) Value {
+	if pkg, ok := prog.packages[obj.Pkg()]; ok {
+		return pkg.values[obj]
+	}
+	return nil
+}
+
+// FuncValue returns the concrete Function denoted by the source-level
+// named function obj, or nil if obj denotes an interface method.
+//
+// TODO(adonovan): check the invariant that obj.Type() matches the
+// result's Signature, both in the params/results and in the receiver.
+//
+func (prog *Program) FuncValue(obj *types.Func) *Function {
+	obj = typeparams.OriginMethod(obj)
+	fn, _ := prog.packageLevelValue(obj).(*Function)
+	return fn
+}
+
+// ConstValue returns the IR Value denoted by the source-level named
+// constant obj.
+//
+func (prog *Program) ConstValue(obj *types.Const) *Const {
+	// TODO(adonovan): opt: share (don't reallocate)
+	// Consts for const objects and constant ast.Exprs.
+
+	// Universal constant? {true,false,nil}
+	if obj.Parent() == types.Universe {
+		return NewConst(obj.Val(), obj.Type())
+	}
+	// Package-level named constant?
+	if v := prog.packageLevelValue(obj); v != nil {
+		return v.(*Const)
+	}
+	return NewConst(obj.Val(), obj.Type())
+}
+
+// VarValue returns the IR Value that corresponds to a specific
+// identifier denoting the source-level named variable obj.
+//
+// VarValue returns nil if a local variable was not found, perhaps
+// because its package was not built, the debug information was not
+// requested during IR construction, or the value was optimized away.
+//
+// ref is the path to an ast.Ident (e.g. from PathEnclosingInterval),
+// and that ident must resolve to obj.
+//
+// pkg is the package enclosing the reference.  (A reference to a var
+// always occurs within a function, so we need to know where to find it.)
+//
+// If the identifier is a field selector and its base expression is
+// non-addressable, then VarValue returns the value of that field.
+// For example:
+//    func f() struct {x int}
+//    f().x  // VarValue(x) returns a *Field instruction of type int
+//
+// All other identifiers denote addressable locations (variables).
+// For them, VarValue may return either the variable's address or its
+// value, even when the expression is evaluated only for its value; the
+// situation is reported by isAddr, the second component of the result.
+//
+// If !isAddr, the returned value is the one associated with the
+// specific identifier.  For example,
+//       var x int    // VarValue(x) returns Const 0 here
+//       x = 1        // VarValue(x) returns Const 1 here
+//
+// It is not specified whether the value or the address is returned in
+// any particular case, as it may depend upon optimizations performed
+// during IR code generation, such as registerization, constant
+// folding, avoidance of materialization of subexpressions, etc.
+//
+func (prog *Program) VarValue(obj *types.Var, pkg *Package, ref []ast.Node) (value Value, isAddr bool) {
+	// All references to a var are local to some function, possibly init.
+	fn := EnclosingFunction(pkg, ref)
+	if fn == nil {
+		return // e.g. def of struct field; IR not built?
+	}
+
+	id := ref[0].(*ast.Ident)
+
+	// Defining ident of a parameter?
+	if id.Pos() == obj.Pos() {
+		for _, param := range fn.Params {
+			if param.Object() == obj {
+				return param, false
+			}
+		}
+	}
+
+	// Other ident?
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			if dr, ok := instr.(*DebugRef); ok {
+				if dr.Pos() == id.Pos() {
+					return dr.X, dr.IsAddr
+				}
+			}
+		}
+	}
+
+	// Defining ident of package-level var?
+	if v := prog.packageLevelValue(obj); v != nil {
+		return v.(*Global), true
+	}
+
+	return // e.g. debug info not requested, or var optimized away
+}

vendor/honnef.co/go/tools/go/ir/staticcheck.conf

@@ -0,0 +1,3 @@
+# ssa/... is mostly imported from upstream and we don't want to
+# deviate from it too much, hence disabling SA1019
+checks = ["inherit", "-SA1019"]

vendor/honnef.co/go/tools/go/ir/util.go

@@ -0,0 +1,149 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines a number of miscellaneous utility functions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"io"
+	"os"
+
+	"honnef.co/go/tools/go/ast/astutil"
+	"honnef.co/go/tools/go/types/typeutil"
+
+	"golang.org/x/exp/typeparams"
+)
+
+//// AST utilities
+
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
+
+// isBlankIdent returns true iff e is an Ident with name "_".
+// They have no associated types.Object, and thus no type.
+//
+func isBlankIdent(e ast.Expr) bool {
+	id, ok := e.(*ast.Ident)
+	return ok && id.Name == "_"
+}
+
+//// Type utilities.  Some of these belong in go/types.
+
+// isPointer returns true for types whose underlying type is a pointer,
+// and for type parameters whose core type is a pointer.
+func isPointer(typ types.Type) bool {
+	if ctyp := typeutil.CoreType(typ); ctyp != nil {
+		_, ok := ctyp.(*types.Pointer)
+		return ok
+	}
+	_, ok := typ.Underlying().(*types.Pointer)
+	return ok
+}
+
+func isInterface(T types.Type) bool { return types.IsInterface(T) }
+
+// deref returns a pointer's element type; otherwise it returns typ.
+func deref(typ types.Type) types.Type {
+	orig := typ
+
+	if t, ok := typ.(*typeparams.TypeParam); ok {
+		if ctyp := typeutil.CoreType(t); ctyp != nil {
+			typ = ctyp
+		}
+	}
+	if p, ok := typ.Underlying().(*types.Pointer); ok {
+		return p.Elem()
+	}
+	return orig
+}
+
+// recvType returns the receiver type of method obj.
+func recvType(obj *types.Func) types.Type {
+	return obj.Type().(*types.Signature).Recv().Type()
+}
+
+// logStack prints the formatted "start" message to stderr and
+// returns a closure that prints the corresponding "end" message.
+// Call using 'defer logStack(...)()' to show builder stack on panic.
+// Don't forget trailing parens!
+//
+func logStack(format string, args ...interface{}) func() {
+	msg := fmt.Sprintf(format, args...)
+	io.WriteString(os.Stderr, msg)
+	io.WriteString(os.Stderr, "\n")
+	return func() {
+		io.WriteString(os.Stderr, msg)
+		io.WriteString(os.Stderr, " end\n")
+	}
+}
+
+// newVar creates a 'var' for use in a types.Tuple.
+func newVar(name string, typ types.Type) *types.Var {
+	return types.NewParam(token.NoPos, nil, name, typ)
+}
+
+// anonVar creates an anonymous 'var' for use in a types.Tuple.
+func anonVar(typ types.Type) *types.Var {
+	return newVar("", typ)
+}
+
+var lenResults = types.NewTuple(anonVar(tInt))
+
+// makeLen returns the len builtin specialized to type func(T)int.
+func makeLen(T types.Type) *Builtin {
+	lenParams := types.NewTuple(anonVar(T))
+	return &Builtin{
+		name: "len",
+		sig:  types.NewSignature(nil, lenParams, lenResults, false),
+	}
+}
+
+type StackMap struct {
+	m []map[Value]Value
+}
+
+func (m *StackMap) Push() {
+	m.m = append(m.m, map[Value]Value{})
+}
+
+func (m *StackMap) Pop() {
+	m.m = m.m[:len(m.m)-1]
+}
+
+func (m *StackMap) Get(key Value) (Value, bool) {
+	for i := len(m.m) - 1; i >= 0; i-- {
+		if v, ok := m.m[i][key]; ok {
+			return v, true
+		}
+	}
+	return nil, false
+}
+
+func (m *StackMap) Set(k Value, v Value) {
+	m.m[len(m.m)-1][k] = v
+}
+
+// Unwrap recursively unwraps Sigma and Copy nodes.
+func Unwrap(v Value) Value {
+	for {
+		switch vv := v.(type) {
+		case *Sigma:
+			v = vv.X
+		case *Copy:
+			v = vv.X
+		default:
+			return v
+		}
+	}
+}
+
+func assert(x bool) {
+	if !x {
+		panic("failed assertion")
+	}
+}

vendor/honnef.co/go/tools/go/ir/wrappers.go

@@ -0,0 +1,387 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines synthesis of Functions that delegate to declared
+// methods; they come in three kinds:
+//
+// (1) wrappers: methods that wrap declared methods, performing
+//     implicit pointer indirections and embedded field selections.
+//
+// (2) thunks: funcs that wrap declared methods.  Like wrappers,
+//     thunks perform indirections and field selections. The thunk's
+//     first parameter is used as the receiver for the method call.
+//
+// (3) bounds: funcs that wrap declared methods.  The bound's sole
+//     free variable, supplied by a closure, is used as the receiver
+//     for the method call.  No indirections or field selections are
+//     performed since they can be done before the call.
+
+import (
+	"fmt"
+	"go/types"
+
+	"golang.org/x/exp/typeparams"
+)
+
+// -- wrappers -----------------------------------------------------------
+
+// makeWrapper returns a synthetic method that delegates to the
+// declared method denoted by meth.Obj(), first performing any
+// necessary pointer indirections or field selections implied by meth.
+//
+// The resulting method's receiver type is meth.Recv().
+//
+// This function is versatile but quite subtle!  Consider the
+// following axes of variation when making changes:
+//   - optional receiver indirection
+//   - optional implicit field selections
+//   - meth.Obj() may denote a concrete or an interface method
+//   - the result may be a thunk or a wrapper.
+//
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+//
+func makeWrapper(prog *Program, sel *types.Selection) *Function {
+	obj := sel.Obj().(*types.Func)       // the declared function
+	sig := sel.Type().(*types.Signature) // type of this wrapper
+
+	var recv *types.Var // wrapper's receiver or thunk's params[0]
+	name := obj.Name()
+	var description Synthetic
+	var start int // first regular param
+	if sel.Kind() == types.MethodExpr {
+		name += "$thunk"
+		description = SyntheticThunk
+		recv = sig.Params().At(0)
+		start = 1
+	} else {
+		description = SyntheticWrapper
+		recv = sig.Recv()
+	}
+
+	if prog.mode&LogSource != 0 {
+		defer logStack("make %s to (%s)", description, recv.Type())()
+	}
+	fn := &Function{
+		name:         name,
+		method:       sel,
+		object:       obj,
+		Signature:    sig,
+		Synthetic:    description,
+		Prog:         prog,
+		functionBody: new(functionBody),
+	}
+	fn.initHTML(prog.PrintFunc)
+	fn.startBody()
+	fn.addSpilledParam(recv, nil)
+	createParams(fn, start)
+
+	indices := sel.Index()
+
+	var v Value = fn.Locals[0] // spilled receiver
+	if isPointer(sel.Recv()) {
+		v = emitLoad(fn, v, nil)
+
+		// For simple indirection wrappers, perform an informative nil-check:
+		// "value method (T).f called using nil *T pointer"
+		if len(indices) == 1 && !isPointer(recvType(obj)) {
+			var c Call
+			c.Call.Value = &Builtin{
+				name: "ir:wrapnilchk",
+				sig: types.NewSignature(nil,
+					types.NewTuple(anonVar(sel.Recv()), anonVar(tString), anonVar(tString)),
+					types.NewTuple(anonVar(sel.Recv())), false),
+			}
+			c.Call.Args = []Value{
+				v,
+				emitConst(fn, stringConst(deref(sel.Recv()).String())),
+				emitConst(fn, stringConst(sel.Obj().Name())),
+			}
+			c.setType(v.Type())
+			v = fn.emit(&c, nil)
+		}
+	}
+
+	// Invariant: v is a pointer, either
+	//   value of *A receiver param, or
+	// address of  A spilled receiver.
+
+	// We use pointer arithmetic (FieldAddr possibly followed by
+	// Load) in preference to value extraction (Field possibly
+	// preceded by Load).
+
+	v = emitImplicitSelections(fn, v, indices[:len(indices)-1], nil)
+
+	// Invariant: v is a pointer, either
+	//   value of implicit *C field, or
+	// address of implicit  C field.
+
+	var c Call
+	if r := recvType(obj); !isInterface(r) { // concrete method
+		if !isPointer(r) {
+			v = emitLoad(fn, v, nil)
+		}
+		c.Call.Value = prog.declaredFunc(obj)
+		c.Call.Args = append(c.Call.Args, v)
+	} else {
+		c.Call.Method = obj
+		c.Call.Value = emitLoad(fn, v, nil)
+	}
+	for _, arg := range fn.Params[1:] {
+		c.Call.Args = append(c.Call.Args, arg)
+	}
+	emitTailCall(fn, &c, nil)
+	fn.finishBody()
+	return fn
+}
+
+// createParams creates parameters for wrapper method fn based on its
+// Signature.Params, which do not include the receiver.
+// start is the index of the first regular parameter to use.
+//
+func createParams(fn *Function, start int) {
+	tparams := fn.Signature.Params()
+	for i, n := start, tparams.Len(); i < n; i++ {
+		fn.addParamObj(tparams.At(i), nil)
+	}
+}
+
+// -- bounds -----------------------------------------------------------
+
+// makeBound returns a bound method wrapper (or "bound"), a synthetic
+// function that delegates to a concrete or interface method denoted
+// by obj.  The resulting function has no receiver, but has one free
+// variable which will be used as the method's receiver in the
+// tail-call.
+//
+// Use MakeClosure with such a wrapper to construct a bound method
+// closure.  e.g.:
+//
+//   type T int          or:  type T interface { meth() }
+//   func (t T) meth()
+//   var t T
+//   f := t.meth
+//   f() // calls t.meth()
+//
+// f is a closure of a synthetic wrapper defined as if by:
+//
+//   f := func() { return t.meth() }
+//
+// Unlike makeWrapper, makeBound need perform no indirection or field
+// selections because that can be done before the closure is
+// constructed.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
+//
+func makeBound(prog *Program, obj *types.Func) *Function {
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+	fn, ok := prog.bounds[obj]
+	if !ok {
+		if prog.mode&LogSource != 0 {
+			defer logStack("%s", SyntheticBound)()
+		}
+		fn = &Function{
+			name:         obj.Name() + "$bound",
+			object:       obj,
+			Signature:    changeRecv(obj.Type().(*types.Signature), nil), // drop receiver
+			Synthetic:    SyntheticBound,
+			Prog:         prog,
+			functionBody: new(functionBody),
+		}
+		fn.initHTML(prog.PrintFunc)
+
+		fv := &FreeVar{name: "recv", typ: recvType(obj), parent: fn}
+		fn.FreeVars = []*FreeVar{fv}
+		fn.startBody()
+		createParams(fn, 0)
+		var c Call
+
+		if !isInterface(recvType(obj)) { // concrete
+			c.Call.Value = prog.declaredFunc(obj)
+			c.Call.Args = []Value{fv}
+		} else {
+			c.Call.Value = fv
+			c.Call.Method = obj
+		}
+		for _, arg := range fn.Params {
+			c.Call.Args = append(c.Call.Args, arg)
+		}
+		emitTailCall(fn, &c, nil)
+		fn.finishBody()
+
+		prog.bounds[obj] = fn
+	}
+	return fn
+}
+
+// -- thunks -----------------------------------------------------------
+
+// makeThunk returns a thunk, a synthetic function that delegates to a
+// concrete or interface method denoted by sel.Obj().  The resulting
+// function has no receiver, but has an additional (first) regular
+// parameter.
+//
+// Precondition: sel.Kind() == types.MethodExpr.
+//
+//   type T int          or:  type T interface { meth() }
+//   func (t T) meth()
+//   f := T.meth
+//   var t T
+//   f(t) // calls t.meth()
+//
+// f is a synthetic wrapper defined as if by:
+//
+//   f := func(t T) { return t.meth() }
+//
+// TODO(adonovan): opt: currently the stub is created even when used
+// directly in a function call: C.f(i, 0).  This is less efficient
+// than inlining the stub.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
+//
+func makeThunk(prog *Program, sel *types.Selection) *Function {
+	if sel.Kind() != types.MethodExpr {
+		panic(sel)
+	}
+
+	key := selectionKey{
+		kind:     sel.Kind(),
+		recv:     sel.Recv(),
+		obj:      sel.Obj(),
+		index:    fmt.Sprint(sel.Index()),
+		indirect: sel.Indirect(),
+	}
+
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	// Canonicalize key.recv to avoid constructing duplicate thunks.
+	canonRecv, ok := prog.canon.At(key.recv).(types.Type)
+	if !ok {
+		canonRecv = key.recv
+		prog.canon.Set(key.recv, canonRecv)
+	}
+	key.recv = canonRecv
+
+	fn, ok := prog.thunks[key]
+	if !ok {
+		fn = makeWrapper(prog, sel)
+		if fn.Signature.Recv() != nil {
+			panic(fn) // unexpected receiver
+		}
+		prog.thunks[key] = fn
+	}
+	return fn
+}
+
+func changeRecv(s *types.Signature, recv *types.Var) *types.Signature {
+	return types.NewSignature(recv, s.Params(), s.Results(), s.Variadic())
+}
+
+// selectionKey is like types.Selection but a usable map key.
+type selectionKey struct {
+	kind     types.SelectionKind
+	recv     types.Type // canonicalized via Program.canon
+	obj      types.Object
+	index    string
+	indirect bool
+}
+
+// makeInstance creates a wrapper function with signature sig that calls the generic function fn.
+// If targs is not nil, fn is a function and targs describes the concrete type arguments.
+// If targs is nil, fn is a method and the type arguments are derived from the receiver.
+func makeInstance(prog *Program, fn *Function, sig *types.Signature, targs *typeparams.TypeList) *Function {
+	if sig.Recv() != nil {
+		assert(targs == nil)
+		// Methods don't have their own type parameters, but the receiver does
+		targs = typeparams.NamedTypeArgs(deref(sig.Recv().Type()).(*types.Named))
+	} else {
+		assert(targs != nil)
+	}
+
+	wrapper := fn.generics.At(targs)
+	if wrapper != nil {
+		return wrapper
+	}
+
+	var name string
+	if sig.Recv() != nil {
+		name = fn.name
+	} else {
+		name = fmt.Sprintf("%s$generic#%d", fn.name, fn.generics.Len())
+	}
+	w := &Function{
+		name:         name,
+		object:       fn.object,
+		Signature:    sig,
+		Synthetic:    SyntheticGeneric,
+		Prog:         prog,
+		functionBody: new(functionBody),
+	}
+	w.initHTML(prog.PrintFunc)
+	w.startBody()
+	if sig.Recv() != nil {
+		w.addParamObj(sig.Recv(), nil)
+	}
+	createParams(w, 0)
+	var c Call
+	c.Call.Value = fn
+	tresults := fn.Signature.Results()
+	if tresults.Len() == 1 {
+		c.typ = tresults.At(0).Type()
+	} else {
+		c.typ = tresults
+	}
+
+	changeType := func(v Value, typ types.Type) Value {
+		if types.Identical(v.Type(), typ) {
+			return v
+		}
+		var c ChangeType
+		c.X = v
+		c.typ = typ
+		return w.emit(&c, nil)
+	}
+
+	for i, arg := range w.Params {
+		if sig.Recv() != nil {
+			if i == 0 {
+				c.Call.Args = append(c.Call.Args, changeType(w.Params[0], fn.Signature.Recv().Type()))
+			} else {
+				c.Call.Args = append(c.Call.Args, changeType(arg, fn.Signature.Params().At(i-1).Type()))
+			}
+		} else {
+			c.Call.Args = append(c.Call.Args, changeType(arg, fn.Signature.Params().At(i).Type()))
+		}
+	}
+	for i := 0; i < targs.Len(); i++ {
+		arg := targs.At(i)
+		c.Call.TypeArgs = append(c.Call.TypeArgs, arg)
+	}
+	results := w.emit(&c, nil)
+	var ret Return
+	switch tresults.Len() {
+	case 0:
+	case 1:
+		ret.Results = []Value{changeType(results, sig.Results().At(0).Type())}
+	default:
+		for i := 0; i < tresults.Len(); i++ {
+			v := emitExtract(w, results, i, nil)
+			ret.Results = append(ret.Results, changeType(v, sig.Results().At(i).Type()))
+		}
+	}
+
+	w.Exit = w.newBasicBlock("exit")
+	emitJump(w, w.Exit, nil)
+	w.currentBlock = w.Exit
+	w.emit(&ret, nil)
+	w.currentBlock = nil
+
+	w.finishBody()
+
+	fn.generics.Set(targs, w)
+	return w
+}

vendor/honnef.co/go/tools/go/ir/write.go

@@ -0,0 +1,5 @@
+package ir
+
+func NewJump(parent *BasicBlock) *Jump {
+	return &Jump{anInstruction{block: parent}, ""}
+}

vendor/honnef.co/go/tools/go/loader/hash.go

@@ -0,0 +1,84 @@
+package loader
+
+import (
+	"fmt"
+	"runtime"
+	"sort"
+	"strings"
+
+	"honnef.co/go/tools/go/buildid"
+	"honnef.co/go/tools/lintcmd/cache"
+)
+
+// computeHash computes a package's hash. The hash is based on all Go
+// files that make up the package, as well as the hashes of imported
+// packages.
+func computeHash(c *cache.Cache, pkg *PackageSpec) (cache.ActionID, error) {
+	key := c.NewHash("package " + pkg.PkgPath)
+	fmt.Fprintf(key, "goos %s goarch %s\n", runtime.GOOS, runtime.GOARCH)
+	fmt.Fprintf(key, "import %q\n", pkg.PkgPath)
+
+	// Compute the hashes of all files making up the package. As an
+	// optimization, we use the build ID that Go already computed for
+	// us, because it is virtually identical to hashed all
+	// CompiledGoFiles.
+	success := false
+	if pkg.ExportFile != "" {
+		id, err := getBuildid(pkg.ExportFile)
+		if err == nil {
+			if idx := strings.IndexRune(id, '/'); idx > -1 {
+				fmt.Fprintf(key, "files %s\n", id[:idx])
+				success = true
+			}
+		}
+	}
+	if !success {
+		for _, f := range pkg.CompiledGoFiles {
+			h, err := cache.FileHash(f)
+			if err != nil {
+				return cache.ActionID{}, err
+			}
+			fmt.Fprintf(key, "file %s %x\n", f, h)
+		}
+	}
+
+	imps := make([]*PackageSpec, 0, len(pkg.Imports))
+	for _, v := range pkg.Imports {
+		imps = append(imps, v)
+	}
+	sort.Slice(imps, func(i, j int) bool {
+		return imps[i].PkgPath < imps[j].PkgPath
+	})
+
+	for _, dep := range imps {
+		if dep.ExportFile == "" {
+			fmt.Fprintf(key, "import %s \n", dep.PkgPath)
+		} else {
+			id, err := getBuildid(dep.ExportFile)
+			if err == nil {
+				fmt.Fprintf(key, "import %s %s\n", dep.PkgPath, id)
+			} else {
+				fh, err := cache.FileHash(dep.ExportFile)
+				if err != nil {
+					return cache.ActionID{}, err
+				}
+				fmt.Fprintf(key, "import %s %x\n", dep.PkgPath, fh)
+			}
+		}
+	}
+	return key.Sum(), nil
+}
+
+var buildidCache = map[string]string{}
+
+func getBuildid(f string) (string, error) {
+	if h, ok := buildidCache[f]; ok {
+		return h, nil
+	}
+	h, err := buildid.ReadFile(f)
+	if err != nil {
+		return "", err
+	}
+	buildidCache[f] = h
+	return h, nil
+}

vendor/honnef.co/go/tools/go/loader/loader.go

@@ -0,0 +1,348 @@
+package loader
+
+import (
+	"errors"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/scanner"
+	"go/token"
+	"go/types"
+	"os"
+	"time"
+
+	"honnef.co/go/tools/config"
+	"honnef.co/go/tools/lintcmd/cache"
+
+	"golang.org/x/exp/typeparams"
+	"golang.org/x/tools/go/gcexportdata"
+	"golang.org/x/tools/go/packages"
+)
+
+const MaxFileSize = 50 * 1024 * 1024 // 50 MB
+
+var errMaxFileSize = errors.New("file exceeds max file size")
+
+type PackageSpec struct {
+	ID      string
+	Name    string
+	PkgPath string
+	// Errors that occurred while building the import graph. These will
+	// primarily be parse errors or failure to resolve imports, but
+	// may also be other errors.
+	Errors          []packages.Error
+	GoFiles         []string
+	CompiledGoFiles []string
+	OtherFiles      []string
+	ExportFile      string
+	Imports         map[string]*PackageSpec
+	TypesSizes      types.Sizes
+	Hash            cache.ActionID
+	Module          *packages.Module
+
+	Config config.Config
+}
+
+func (spec *PackageSpec) String() string {
+	return spec.ID
+}
+
+type Package struct {
+	*PackageSpec
+
+	// Errors that occurred while loading the package. These will
+	// primarily be parse or type errors, but may also be lower-level
+	// failures such as file-system ones.
+	Errors    []packages.Error
+	Types     *types.Package
+	Fset      *token.FileSet
+	Syntax    []*ast.File
+	TypesInfo *types.Info
+}
+
+// Graph resolves patterns and returns packages with all the
+// information required to later load type information, and optionally
+// syntax trees.
+//
+// The provided config can set any setting with the exception of Mode.
+func Graph(c *cache.Cache, cfg *packages.Config, patterns ...string) ([]*PackageSpec, error) {
+	var dcfg packages.Config
+	if cfg != nil {
+		dcfg = *cfg
+	}
+	dcfg.Mode = packages.NeedName |
+		packages.NeedImports |
+		packages.NeedDeps |
+		packages.NeedExportsFile |
+		packages.NeedFiles |
+		packages.NeedCompiledGoFiles |
+		packages.NeedTypesSizes |
+		packages.NeedModule
+	pkgs, err := packages.Load(&dcfg, patterns...)
+	if err != nil {
+		return nil, err
+	}
+
+	m := map[*packages.Package]*PackageSpec{}
+	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
+		spec := &PackageSpec{
+			ID:              pkg.ID,
+			Name:            pkg.Name,
+			PkgPath:         pkg.PkgPath,
+			Errors:          pkg.Errors,
+			GoFiles:         pkg.GoFiles,
+			CompiledGoFiles: pkg.CompiledGoFiles,
+			OtherFiles:      pkg.OtherFiles,
+			ExportFile:      pkg.ExportFile,
+			Imports:         map[string]*PackageSpec{},
+			TypesSizes:      pkg.TypesSizes,
+			Module:          pkg.Module,
+		}
+		for path, imp := range pkg.Imports {
+			spec.Imports[path] = m[imp]
+		}
+		if cdir := config.Dir(pkg.GoFiles); cdir != "" {
+			cfg, err := config.Load(cdir)
+			if err != nil {
+				spec.Errors = append(spec.Errors, convertError(err)...)
+			}
+			spec.Config = cfg
+		} else {
+			spec.Config = config.DefaultConfig
+		}
+		spec.Hash, err = computeHash(c, spec)
+		if err != nil {
+			spec.Errors = append(spec.Errors, convertError(err)...)
+		}
+		m[pkg] = spec
+	})
+	out := make([]*PackageSpec, 0, len(pkgs))
+	for _, pkg := range pkgs {
+		if len(pkg.CompiledGoFiles) == 0 && len(pkg.Errors) == 0 && pkg.PkgPath != "unsafe" {
+			// If a package consists only of test files, then
+			// go/packages incorrectly(?) returns an empty package for
+			// the non-test variant. Get rid of those packages. See
+			// #646.
+			//
+			// Do not, however, skip packages that have errors. Those,
+			// too, may have no files, but we want to print the
+			// errors.
+			continue
+		}
+		out = append(out, m[pkg])
+	}
+
+	return out, nil
+}
+
+type program struct {
+	fset     *token.FileSet
+	packages map[string]*types.Package
+}
+
+type Stats struct {
+	Source time.Duration
+	Export map[*PackageSpec]time.Duration
+}
+
+// Load loads the package described in spec. Imports will be loaded
+// from export data, while the package itself will be loaded from
+// source.
+//
+// An error will only be returned for system failures, such as failure
+// to read export data from disk. Syntax and type errors, among
+// others, will only populate the returned package's Errors field.
+func Load(spec *PackageSpec) (*Package, Stats, error) {
+	prog := &program{
+		fset:     token.NewFileSet(),
+		packages: map[string]*types.Package{},
+	}
+
+	stats := Stats{
+		Export: map[*PackageSpec]time.Duration{},
+	}
+	for _, imp := range spec.Imports {
+		if imp.PkgPath == "unsafe" {
+			continue
+		}
+		t := time.Now()
+		_, err := prog.loadFromExport(imp)
+		stats.Export[imp] = time.Since(t)
+		if err != nil {
+			return nil, stats, err
+		}
+	}
+	t := time.Now()
+	pkg, err := prog.loadFromSource(spec)
+	if err == errMaxFileSize {
+		pkg, err = prog.loadFromExport(spec)
+	}
+	stats.Source = time.Since(t)
+	return pkg, stats, err
+}
+
+// loadFromExport loads a package from export data.
+func (prog *program) loadFromExport(spec *PackageSpec) (*Package, error) {
+	// log.Printf("Loading package %s from export", spec)
+	if spec.ExportFile == "" {
+		return nil, fmt.Errorf("no export data for %q", spec.ID)
+	}
+	f, err := os.Open(spec.ExportFile)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	r, err := gcexportdata.NewReader(f)
+	if err != nil {
+		return nil, err
+	}
+	tpkg, err := gcexportdata.Read(r, prog.fset, prog.packages, spec.PkgPath)
+	if err != nil {
+		return nil, err
+	}
+	pkg := &Package{
+		PackageSpec: spec,
+		Types:       tpkg,
+		Fset:        prog.fset,
+	}
+	// runtime.SetFinalizer(pkg, func(pkg *Package) {
+	// 	log.Println("Unloading package", pkg.PkgPath)
+	// })
+	return pkg, nil
+}
+
+// loadFromSource loads a package from source. All of its dependencies
+// must have been loaded already.
+func (prog *program) loadFromSource(spec *PackageSpec) (*Package, error) {
+	if len(spec.Errors) > 0 {
+		panic("LoadFromSource called on package with errors")
+	}
+
+	pkg := &Package{
+		PackageSpec: spec,
+		Types:       types.NewPackage(spec.PkgPath, spec.Name),
+		Syntax:      make([]*ast.File, len(spec.CompiledGoFiles)),
+		Fset:        prog.fset,
+		TypesInfo: &types.Info{
+			Types:      make(map[ast.Expr]types.TypeAndValue),
+			Defs:       make(map[*ast.Ident]types.Object),
+			Uses:       make(map[*ast.Ident]types.Object),
+			Implicits:  make(map[ast.Node]types.Object),
+			Scopes:     make(map[ast.Node]*types.Scope),
+			Selections: make(map[*ast.SelectorExpr]*types.Selection),
+		},
+	}
+	typeparams.InitInstances(pkg.TypesInfo)
+	// runtime.SetFinalizer(pkg, func(pkg *Package) {
+	// 	log.Println("Unloading package", pkg.PkgPath)
+	// })
+
+	// OPT(dh): many packages have few files, much fewer than there
+	// are CPU cores. Additionally, parsing each individual file is
+	// very fast. A naive parallel implementation of this loop won't
+	// be faster, and tends to be slower due to extra scheduling,
+	// bookkeeping and potentially false sharing of cache lines.
+	for i, file := range spec.CompiledGoFiles {
+		f, err := os.Open(file)
+		if err != nil {
+			return nil, err
+		}
+		fi, err := f.Stat()
+		if err != nil {
+			return nil, err
+		}
+		if fi.Size() >= MaxFileSize {
+			return nil, errMaxFileSize
+		}
+		af, err := parser.ParseFile(prog.fset, file, f, parser.ParseComments)
+		f.Close()
+		if err != nil {
+			pkg.Errors = append(pkg.Errors, convertError(err)...)
+			return pkg, nil
+		}
+		pkg.Syntax[i] = af
+	}
+	importer := func(path string) (*types.Package, error) {
+		if path == "unsafe" {
+			return types.Unsafe, nil
+		}
+		if path == "C" {
+			// go/packages doesn't tell us that cgo preprocessing
+			// failed. When we subsequently try to parse the package,
+			// we'll encounter the raw C import.
+			return nil, errors.New("cgo preprocessing failed")
+		}
+		ispecpkg := spec.Imports[path]
+		if ispecpkg == nil {
+			return nil, fmt.Errorf("trying to import %q in the context of %q returned nil PackageSpec", path, spec)
+		}
+		ipkg := prog.packages[ispecpkg.PkgPath]
+		if ipkg == nil {
+			return nil, fmt.Errorf("trying to import %q (%q) in the context of %q returned nil PackageSpec", ispecpkg.PkgPath, path, spec)
+		}
+		return ipkg, nil
+	}
+	tc := &types.Config{
+		Importer: importerFunc(importer),
+		Error: func(err error) {
+			pkg.Errors = append(pkg.Errors, convertError(err)...)
+		},
+	}
+	types.NewChecker(tc, pkg.Fset, pkg.Types, pkg.TypesInfo).Files(pkg.Syntax)
+	return pkg, nil
+}
+
+func convertError(err error) []packages.Error {
+	var errs []packages.Error
+	// taken from go/packages
+	switch err := err.(type) {
+	case packages.Error:
+		// from driver
+		errs = append(errs, err)
+
+	case *os.PathError:
+		// from parser
+		errs = append(errs, packages.Error{
+			Pos:  err.Path + ":1",
+			Msg:  err.Err.Error(),
+			Kind: packages.ParseError,
+		})
+
+	case scanner.ErrorList:
+		// from parser
+		for _, err := range err {
+			errs = append(errs, packages.Error{
+				Pos:  err.Pos.String(),
+				Msg:  err.Msg,
+				Kind: packages.ParseError,
+			})
+		}
+
+	case types.Error:
+		// from type checker
+		errs = append(errs, packages.Error{
+			Pos:  err.Fset.Position(err.Pos).String(),
+			Msg:  err.Msg,
+			Kind: packages.TypeError,
+		})
+
+	case config.ParseError:
+		errs = append(errs, packages.Error{
+			Pos:  fmt.Sprintf("%s:%d", err.Filename, err.Line),
+			Msg:  fmt.Sprintf("%s (last key parsed: %q)", err.Message, err.LastKey),
+			Kind: packages.ParseError,
+		})
+	default:
+		errs = append(errs, packages.Error{
+			Pos:  "-",
+			Msg:  err.Error(),
+			Kind: packages.UnknownError,
+		})
+	}
+	return errs
+}
+
+type importerFunc func(path string) (*types.Package, error)
+
+func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }

vendor/honnef.co/go/tools/go/types/typeutil/ext.go

@@ -0,0 +1,18 @@
+package typeutil
+
+import (
+	"fmt"
+	"go/types"
+)
+
+type Iterator struct {
+	elem types.Type
+}
+
+func (t *Iterator) Underlying() types.Type { return t }
+func (t *Iterator) String() string         { return fmt.Sprintf("iterator(%s)", t.elem) }
+func (t *Iterator) Elem() types.Type       { return t.elem }
+
+func NewIterator(elem types.Type) *Iterator {
+	return &Iterator{elem: elem}
+}

vendor/honnef.co/go/tools/go/types/typeutil/typeparams.go

@@ -0,0 +1,106 @@
+package typeutil
+
+import (
+	"errors"
+	"go/types"
+
+	"golang.org/x/exp/typeparams"
+)
+
+type TypeSet struct {
+	Terms []*typeparams.Term
+	empty bool
+}
+
+func NewTypeSet(typ types.Type) TypeSet {
+	terms, err := typeparams.NormalTerms(typ)
+	if err != nil {
+		if errors.Is(err, typeparams.ErrEmptyTypeSet) {
+			return TypeSet{nil, true}
+		} else {
+			// We couldn't determine the type set. Assume it's all types.
+			return TypeSet{nil, false}
+		}
+	}
+	return TypeSet{terms, false}
+}
+
+// CoreType returns the type set's core type, or nil if it has none.
+// The function only looks at type terms and may thus return core types for some empty type sets, such as
+// 'interface { map[int]string; foo() }'
+func (ts TypeSet) CoreType() types.Type {
+	if len(ts.Terms) == 0 {
+		// Either the type set is empty, or it isn't constrained. Either way it doesn't have a core type.
+		return nil
+	}
+	typ := ts.Terms[0].Type().Underlying()
+	for _, term := range ts.Terms[1:] {
+		ut := term.Type().Underlying()
+		if types.Identical(typ, ut) {
+			continue
+		}
+
+		ch1, ok := typ.(*types.Chan)
+		if !ok {
+			return nil
+		}
+		ch2, ok := ut.(*types.Chan)
+		if !ok {
+			return nil
+		}
+		if ch1.Dir() == types.SendRecv {
+			// typ is currently a bidirectional channel. The term's type is either also bidirectional, or
+			// unidirectional. Use the term's type.
+			typ = ut
+		} else if ch1.Dir() != ch2.Dir() {
+			// typ is not bidirectional and typ and term disagree about the direction
+			return nil
+		}
+	}
+	return typ
+}
+
+// CoreType is a wrapper for NewTypeSet(typ).CoreType()
+func CoreType(typ types.Type) types.Type {
+	return NewTypeSet(typ).CoreType()
+}
+
+// All calls fn for each term in the type set and reports whether all invocations returned true.
+// If the type set is empty or unconstrained, All immediately returns false.
+func (ts TypeSet) All(fn func(*typeparams.Term) bool) bool {
+	if len(ts.Terms) == 0 {
+		return false
+	}
+	for _, term := range ts.Terms {
+		if !fn(term) {
+			return false
+		}
+	}
+	return true
+}
+
+// Any calls fn for each term in the type set and reports whether any invocation returned true.
+// It stops after the first call that returned true.
+func (ts TypeSet) Any(fn func(*typeparams.Term) bool) bool {
+	for _, term := range ts.Terms {
+		if fn(term) {
+			return true
+		}
+	}
+	return false
+}
+
+// All is a wrapper for NewTypeSet(typ).All(fn).
+func All(typ types.Type, fn func(*typeparams.Term) bool) bool {
+	return NewTypeSet(typ).All(fn)
+}
+
+// Any is a wrapper for NewTypeSet(typ).Any(fn).
+func Any(typ types.Type, fn func(*typeparams.Term) bool) bool {
+	return NewTypeSet(typ).Any(fn)
+}
+
+func IsSlice(term *typeparams.Term) bool {
+	_, ok := term.Type().Underlying().(*types.Slice)
+	return ok
+}

vendor/honnef.co/go/tools/go/types/typeutil/upstream.go

@@ -0,0 +1,25 @@
+package typeutil
+
+import (
+	"go/ast"
+	"go/types"
+	_ "unsafe"
+
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+type MethodSetCache = typeutil.MethodSetCache
+type Map = typeutil.Map
+type Hasher = typeutil.Hasher
+
+func Callee(info *types.Info, call *ast.CallExpr) types.Object {
+	return typeutil.Callee(info, call)
+}
+
+func IntuitiveMethodSet(T types.Type, msets *MethodSetCache) []*types.Selection {
+	return typeutil.IntuitiveMethodSet(T, msets)
+}
+
+func MakeHasher() Hasher {
+	return typeutil.MakeHasher()
+}

vendor/honnef.co/go/tools/go/types/typeutil/util.go

@@ -0,0 +1,131 @@
+package typeutil
+
+import (
+	"bytes"
+	"go/types"
+	"sync"
+)
+
+var bufferPool = &sync.Pool{
+	New: func() interface{} {
+		buf := bytes.NewBuffer(nil)
+		buf.Grow(64)
+		return buf
+	},
+}
+
+func FuncName(f *types.Func) string {
+	buf := bufferPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	if f.Type() != nil {
+		sig := f.Type().(*types.Signature)
+		if recv := sig.Recv(); recv != nil {
+			buf.WriteByte('(')
+			if _, ok := recv.Type().(*types.Interface); ok {
+				// gcimporter creates abstract methods of
+				// named interfaces using the interface type
+				// (not the named type) as the receiver.
+				// Don't print it in full.
+				buf.WriteString("interface")
+			} else {
+				types.WriteType(buf, recv.Type(), nil)
+			}
+			buf.WriteByte(')')
+			buf.WriteByte('.')
+		} else if f.Pkg() != nil {
+			writePackage(buf, f.Pkg())
+		}
+	}
+	buf.WriteString(f.Name())
+	s := buf.String()
+	bufferPool.Put(buf)
+	return s
+}
+
+func writePackage(buf *bytes.Buffer, pkg *types.Package) {
+	if pkg == nil {
+		return
+	}
+	s := pkg.Path()
+	if s != "" {
+		buf.WriteString(s)
+		buf.WriteByte('.')
+	}
+}
+
+// Dereference returns a pointer's element type; otherwise it returns
+// T.
+func Dereference(T types.Type) types.Type {
+	if p, ok := T.Underlying().(*types.Pointer); ok {
+		return p.Elem()
+	}
+	return T
+}
+
+// DereferenceR returns a pointer's element type; otherwise it returns
+// T. If the element type is itself a pointer, DereferenceR will be
+// applied recursively.
+func DereferenceR(T types.Type) types.Type {
+	if p, ok := T.Underlying().(*types.Pointer); ok {
+		return DereferenceR(p.Elem())
+	}
+	return T
+}
+
+func IsObject(obj types.Object, name string) bool {
+	var path string
+	if pkg := obj.Pkg(); pkg != nil {
+		path = pkg.Path() + "."
+	}
+	return path+obj.Name() == name
+}
+
+// OPT(dh): IsType is kind of expensive; should we really use it?
+func IsType(T types.Type, name string) bool { return types.TypeString(T, nil) == name }
+
+func IsPointerLike(T types.Type) bool {
+	switch T := T.Underlying().(type) {
+	case *types.Interface, *types.Chan, *types.Map, *types.Signature, *types.Pointer, *types.Slice:
+		return true
+	case *types.Basic:
+		return T.Kind() == types.UnsafePointer
+	}
+	return false
+}
+
+type Field struct {
+	Var  *types.Var
+	Tag  string
+	Path []int
+}
+
+// FlattenFields recursively flattens T and embedded structs,
+// returning a list of fields. If multiple fields with the same name
+// exist, all will be returned.
+func FlattenFields(T *types.Struct) []Field {
+	return flattenFields(T, nil, nil)
+}
+
+func flattenFields(T *types.Struct, path []int, seen map[types.Type]bool) []Field {
+	if seen == nil {
+		seen = map[types.Type]bool{}
+	}
+	if seen[T] {
+		return nil
+	}
+	seen[T] = true
+	var out []Field
+	for i := 0; i < T.NumFields(); i++ {
+		field := T.Field(i)
+		tag := T.Tag(i)
+		np := append(path[:len(path):len(path)], i)
+		if field.Anonymous() {
+			if s, ok := Dereference(field.Type()).Underlying().(*types.Struct); ok {
+				out = append(out, flattenFields(s, np, seen)...)
+			}
+		} else {
+			out = append(out, Field{field, tag, np})
+		}
+	}
+	return out
+}

vendor/honnef.co/go/tools/internal/passes/buildir/buildir.go

@@ -0,0 +1,107 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package buildir defines an Analyzer that constructs the IR
+// of an error-free package and returns the set of all
+// functions within it. It does not report any diagnostics itself but
+// may be used as an input to other analyzers.
+//
+// THIS INTERFACE IS EXPERIMENTAL AND MAY BE SUBJECT TO INCOMPATIBLE CHANGE.
+package buildir
+
+import (
+	"go/ast"
+	"go/types"
+	"reflect"
+
+	"honnef.co/go/tools/go/ir"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+type noReturn struct {
+	Kind ir.NoReturn
+}
+
+func (*noReturn) AFact() {}
+
+var Analyzer = &analysis.Analyzer{
+	Name:       "buildir",
+	Doc:        "build IR for later passes",
+	Run:        run,
+	ResultType: reflect.TypeOf(new(IR)),
+	FactTypes:  []analysis.Fact{new(noReturn)},
+}
+
+// IR provides intermediate representation for all the
+// non-blank source functions in the current package.
+type IR struct {
+	Pkg      *ir.Package
+	SrcFuncs []*ir.Function
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	// Plundered from ssautil.BuildPackage.
+
+	// We must create a new Program for each Package because the
+	// analysis API provides no place to hang a Program shared by
+	// all Packages. Consequently, IR Packages and Functions do not
+	// have a canonical representation across an analysis session of
+	// multiple packages. This is unlikely to be a problem in
+	// practice because the analysis API essentially forces all
+	// packages to be analysed independently, so any given call to
+	// Analysis.Run on a package will see only IR objects belonging
+	// to a single Program.
+
+	mode := ir.GlobalDebug
+
+	prog := ir.NewProgram(pass.Fset, mode)
+
+	// Create IR packages for all imports.
+	// Order is not significant.
+	created := make(map[*types.Package]bool)
+	var createAll func(pkgs []*types.Package)
+	createAll = func(pkgs []*types.Package) {
+		for _, p := range pkgs {
+			if !created[p] {
+				created[p] = true
+				irpkg := prog.CreatePackage(p, nil, nil, true)
+				for _, fn := range irpkg.Functions {
+					if ast.IsExported(fn.Name()) {
+						var noRet noReturn
+						if pass.ImportObjectFact(fn.Object(), &noRet) {
+							fn.NoReturn = noRet.Kind
+						}
+					}
+				}
+				createAll(p.Imports())
+			}
+		}
+	}
+	createAll(pass.Pkg.Imports())
+
+	// Create and build the primary package.
+	irpkg := prog.CreatePackage(pass.Pkg, pass.Files, pass.TypesInfo, false)
+	irpkg.Build()
+
+	// Compute list of source functions, including literals,
+	// in source order.
+	var addAnons func(f *ir.Function)
+	funcs := make([]*ir.Function, len(irpkg.Functions))
+	copy(funcs, irpkg.Functions)
+	addAnons = func(f *ir.Function) {
+		for _, anon := range f.AnonFuncs {
+			funcs = append(funcs, anon)
+			addAnons(anon)
+		}
+	}
+	for _, fn := range irpkg.Functions {
+		addAnons(fn)
+		if fn.NoReturn > 0 {
+			pass.ExportObjectFact(fn.Object(), &noReturn{fn.NoReturn})
+		}
+	}
+
+	return &IR{Pkg: irpkg, SrcFuncs: funcs}, nil
+}

vendor/honnef.co/go/tools/internal/renameio/UPSTREAM

@@ -0,0 +1,2 @@
+This package is a copy of cmd/go/internal/renameio.
+The upstream package no longer exists, as the Go project replaced all of its uses with the lockedfile package.

vendor/honnef.co/go/tools/internal/renameio/renameio.go

@@ -0,0 +1,93 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package renameio writes files atomically by renaming temporary files.
+package renameio
+
+import (
+	"bytes"
+	"io"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"strconv"
+
+	"honnef.co/go/tools/internal/robustio"
+)
+
+const patternSuffix = ".tmp"
+
+// Pattern returns a glob pattern that matches the unrenamed temporary files
+// created when writing to filename.
+func Pattern(filename string) string {
+	return filepath.Join(filepath.Dir(filename), filepath.Base(filename)+patternSuffix)
+}
+
+// WriteFile is like ioutil.WriteFile, but first writes data to an arbitrary
+// file in the same directory as filename, then renames it atomically to the
+// final name.
+//
+// That ensures that the final location, if it exists, is always a complete file.
+func WriteFile(filename string, data []byte, perm os.FileMode) (err error) {
+	return WriteToFile(filename, bytes.NewReader(data), perm)
+}
+
+// WriteToFile is a variant of WriteFile that accepts the data as an io.Reader
+// instead of a slice.
+func WriteToFile(filename string, data io.Reader, perm os.FileMode) (err error) {
+	f, err := tempFile(filepath.Dir(filename), filepath.Base(filename), perm)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		// Only call os.Remove on f.Name() if we failed to rename it: otherwise,
+		// some other process may have created a new file with the same name after
+		// that.
+		if err != nil {
+			f.Close()
+			os.Remove(f.Name())
+		}
+	}()
+
+	if _, err := io.Copy(f, data); err != nil {
+		return err
+	}
+	// Sync the file before renaming it: otherwise, after a crash the reader may
+	// observe a 0-length file instead of the actual contents.
+	// See https://golang.org/issue/22397#issuecomment-380831736.
+	if err := f.Sync(); err != nil {
+		return err
+	}
+	if err := f.Close(); err != nil {
+		return err
+	}
+
+	return robustio.Rename(f.Name(), filename)
+}
+
+// ReadFile is like ioutil.ReadFile, but on Windows retries spurious errors that
+// may occur if the file is concurrently replaced.
+//
+// Errors are classified heuristically and retries are bounded, so even this
+// function may occasionally return a spurious error on Windows.
+// If so, the error will likely wrap one of:
+// 	- syscall.ERROR_ACCESS_DENIED
+// 	- syscall.ERROR_FILE_NOT_FOUND
+// 	- internal/syscall/windows.ERROR_SHARING_VIOLATION
+func ReadFile(filename string) ([]byte, error) {
+	return robustio.ReadFile(filename)
+}
+
+// tempFile creates a new temporary file with given permission bits.
+func tempFile(dir, prefix string, perm os.FileMode) (f *os.File, err error) {
+	for i := 0; i < 10000; i++ {
+		name := filepath.Join(dir, prefix+strconv.Itoa(rand.Intn(1000000000))+patternSuffix)
+		f, err = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, perm)
+		if os.IsExist(err) {
+			continue
+		}
+		break
+	}
+	return
+}

vendor/honnef.co/go/tools/internal/robustio/UPSTREAM

@@ -0,0 +1,6 @@
+This package is a copy of cmd/go/internal/robustio.
+It is mostly in sync with upstream according to the last commit we've looked at,
+with the exception of still using I/O functions that work with older Go versions.
+
+The last upstream commit we've looked at was:
+06ac303f6a14b133254f757e54599c48e3c2a4ad

vendor/honnef.co/go/tools/internal/robustio/robustio.go

@@ -0,0 +1,53 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package robustio wraps I/O functions that are prone to failure on Windows,
+// transparently retrying errors up to an arbitrary timeout.
+//
+// Errors are classified heuristically and retries are bounded, so the functions
+// in this package do not completely eliminate spurious errors. However, they do
+// significantly reduce the rate of failure in practice.
+//
+// If so, the error will likely wrap one of:
+// The functions in this package do not completely eliminate spurious errors,
+// but substantially reduce their rate of occurrence in practice.
+package robustio
+
+// Rename is like os.Rename, but on Windows retries errors that may occur if the
+// file is concurrently read or overwritten.
+//
+// (See golang.org/issue/31247 and golang.org/issue/32188.)
+func Rename(oldpath, newpath string) error {
+	return rename(oldpath, newpath)
+}
+
+// ReadFile is like ioutil.ReadFile, but on Windows retries errors that may
+// occur if the file is concurrently replaced.
+//
+// (See golang.org/issue/31247 and golang.org/issue/32188.)
+func ReadFile(filename string) ([]byte, error) {
+	return readFile(filename)
+}
+
+// RemoveAll is like os.RemoveAll, but on Windows retries errors that may occur
+// if an executable file in the directory has recently been executed.
+//
+// (See golang.org/issue/19491.)
+func RemoveAll(path string) error {
+	return removeAll(path)
+}
+
+// IsEphemeralError reports whether err is one of the errors that the functions
+// in this package attempt to mitigate.
+//
+// Errors considered ephemeral include:
+// 	- syscall.ERROR_ACCESS_DENIED
+// 	- syscall.ERROR_FILE_NOT_FOUND
+// 	- internal/syscall/windows.ERROR_SHARING_VIOLATION
+//
+// This set may be expanded in the future; programs must not rely on the
+// non-ephemerality of any given error.
+func IsEphemeralError(err error) bool {
+	return isEphemeralError(err)
+}

vendor/honnef.co/go/tools/internal/robustio/robustio_darwin.go

@@ -0,0 +1,21 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package robustio
+
+import (
+	"errors"
+	"syscall"
+)
+
+const errFileNotFound = syscall.ENOENT
+
+// isEphemeralError returns true if err may be resolved by waiting.
+func isEphemeralError(err error) bool {
+	var errno syscall.Errno
+	if errors.As(err, &errno) {
+		return errno == errFileNotFound
+	}
+	return false
+}

vendor/honnef.co/go/tools/internal/robustio/robustio_flaky.go

@@ -0,0 +1,93 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows || darwin
+// +build windows darwin
+
+package robustio
+
+import (
+	"errors"
+	"io/ioutil"
+	"math/rand"
+	"os"
+	"syscall"
+	"time"
+)
+
+const arbitraryTimeout = 2000 * time.Millisecond
+
+// retry retries ephemeral errors from f up to an arbitrary timeout
+// to work around filesystem flakiness on Windows and Darwin.
+func retry(f func() (err error, mayRetry bool)) error {
+	var (
+		bestErr     error
+		lowestErrno syscall.Errno
+		start       time.Time
+		nextSleep   time.Duration = 1 * time.Millisecond
+	)
+	for {
+		err, mayRetry := f()
+		if err == nil || !mayRetry {
+			return err
+		}
+
+		var errno syscall.Errno
+		if errors.As(err, &errno) && (lowestErrno == 0 || errno < lowestErrno) {
+			bestErr = err
+			lowestErrno = errno
+		} else if bestErr == nil {
+			bestErr = err
+		}
+
+		if start.IsZero() {
+			start = time.Now()
+		} else if d := time.Since(start) + nextSleep; d >= arbitraryTimeout {
+			break
+		}
+		time.Sleep(nextSleep)
+		nextSleep += time.Duration(rand.Int63n(int64(nextSleep)))
+	}
+
+	return bestErr
+}
+
+// rename is like os.Rename, but retries ephemeral errors.
+//
+// On Windows it wraps os.Rename, which (as of 2019-06-04) uses MoveFileEx with
+// MOVEFILE_REPLACE_EXISTING.
+//
+// Windows also provides a different system call, ReplaceFile,
+// that provides similar semantics, but perhaps preserves more metadata. (The
+// documentation on the differences between the two is very sparse.)
+//
+// Empirical error rates with MoveFileEx are lower under modest concurrency, so
+// for now we're sticking with what the os package already provides.
+func rename(oldpath, newpath string) (err error) {
+	return retry(func() (err error, mayRetry bool) {
+		err = os.Rename(oldpath, newpath)
+		return err, isEphemeralError(err)
+	})
+}
+
+// readFile is like ioutil.ReadFile, but retries ephemeral errors.
+func readFile(filename string) ([]byte, error) {
+	var b []byte
+	err := retry(func() (err error, mayRetry bool) {
+		b, err = ioutil.ReadFile(filename)
+
+		// Unlike in rename, we do not retry errFileNotFound here: it can occur
+		// as a spurious error, but the file may also genuinely not exist, so the
+		// increase in robustness is probably not worth the extra latency.
+		return err, isEphemeralError(err) && !errors.Is(err, errFileNotFound)
+	})
+	return b, err
+}
+
+func removeAll(path string) error {
+	return retry(func() (err error, mayRetry bool) {
+		err = os.RemoveAll(path)
+		return err, isEphemeralError(err)
+	})
+}

vendor/honnef.co/go/tools/internal/robustio/robustio_other.go

@@ -0,0 +1,29 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !windows && !darwin
+// +build !windows,!darwin
+
+package robustio
+
+import (
+	"io/ioutil"
+	"os"
+)
+
+func rename(oldpath, newpath string) error {
+	return os.Rename(oldpath, newpath)
+}
+
+func readFile(filename string) ([]byte, error) {
+	return ioutil.ReadFile(filename)
+}
+
+func removeAll(path string) error {
+	return os.RemoveAll(path)
+}
+
+func isEphemeralError(err error) bool {
+	return false
+}

vendor/honnef.co/go/tools/internal/robustio/robustio_windows.go

@@ -0,0 +1,27 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package robustio
+
+import (
+	"errors"
+	"syscall"
+)
+
+const ERROR_SHARING_VIOLATION = 32
+const errFileNotFound = syscall.ERROR_FILE_NOT_FOUND
+
+// isEphemeralError returns true if err may be resolved by waiting.
+func isEphemeralError(err error) bool {
+	var errno syscall.Errno
+	if errors.As(err, &errno) {
+		switch errno {
+		case syscall.ERROR_ACCESS_DENIED,
+			syscall.ERROR_FILE_NOT_FOUND,
+			ERROR_SHARING_VIOLATION:
+			return true
+		}
+	}
+	return false
+}

vendor/honnef.co/go/tools/internal/sharedcheck/lint.go

@@ -0,0 +1,208 @@
+package sharedcheck
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/edit"
+	"honnef.co/go/tools/analysis/facts"
+	"honnef.co/go/tools/analysis/report"
+	"honnef.co/go/tools/go/ast/astutil"
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/go/ir/irutil"
+	"honnef.co/go/tools/go/types/typeutil"
+	"honnef.co/go/tools/internal/passes/buildir"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+)
+
+func CheckRangeStringRunes(pass *analysis.Pass) (interface{}, error) {
+	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
+		cb := func(node ast.Node) bool {
+			rng, ok := node.(*ast.RangeStmt)
+			if !ok || !astutil.IsBlank(rng.Key) {
+				return true
+			}
+
+			v, _ := fn.ValueForExpr(rng.X)
+
+			// Check that we're converting from string to []rune
+			val, _ := v.(*ir.Convert)
+			if val == nil {
+				return true
+			}
+			Tsrc, ok := typeutil.CoreType(val.X.Type()).(*types.Basic)
+			if !ok || Tsrc.Kind() != types.String {
+				return true
+			}
+			Tdst, ok := typeutil.CoreType(val.Type()).(*types.Slice)
+			if !ok {
+				return true
+			}
+			TdstElem, ok := Tdst.Elem().(*types.Basic)
+			if !ok || TdstElem.Kind() != types.Int32 {
+				return true
+			}
+
+			// Check that the result of the conversion is only used to
+			// range over
+			refs := val.Referrers()
+			if refs == nil {
+				return true
+			}
+
+			// Expect two refs: one for obtaining the length of the slice,
+			// one for accessing the elements
+			if len(irutil.FilterDebug(*refs)) != 2 {
+				// TODO(dh): right now, we check that only one place
+				// refers to our slice. This will miss cases such as
+				// ranging over the slice twice. Ideally, we'd ensure that
+				// the slice is only used for ranging over (without
+				// accessing the key), but that is harder to do because in
+				// IR form, ranging over a slice looks like an ordinary
+				// loop with index increments and slice accesses. We'd
+				// have to look at the associated AST node to check that
+				// it's a range statement.
+				return true
+			}
+
+			pass.Reportf(rng.Pos(), "should range over string, not []rune(string)")
+
+			return true
+		}
+		if source := fn.Source(); source != nil {
+			ast.Inspect(source, cb)
+		}
+	}
+	return nil, nil
+}
+
+// RedundantTypeInDeclarationChecker returns a checker that flags variable declarations with redundantly specified types.
+// That is, it flags 'var v T = e' where e's type is identical to T and 'var v = e' (or 'v := e') would have the same effect.
+//
+// It does not flag variables under the following conditions, to reduce the number of false positives:
+// - global variables – these often specify types to aid godoc
+// - files that use cgo – cgo code generation and pointer checking emits redundant types
+//
+// It does not flag variables under the following conditions, unless flagHelpfulTypes is true, to reduce the number of noisy positives:
+// - packages that import syscall or unsafe – these sometimes use this form of assignment to make sure types are as expected
+// - variables named the blank identifier – a pattern used to confirm the types of variables
+// - untyped expressions on the rhs – the explicitness might aid readability
+func RedundantTypeInDeclarationChecker(verb string, flagHelpfulTypes bool) *analysis.Analyzer {
+	fn := func(pass *analysis.Pass) (interface{}, error) {
+		eval := func(expr ast.Expr) (types.TypeAndValue, error) {
+			info := &types.Info{
+				Types: map[ast.Expr]types.TypeAndValue{},
+			}
+			err := types.CheckExpr(pass.Fset, pass.Pkg, expr.Pos(), expr, info)
+			return info.Types[expr], err
+		}
+
+		if !flagHelpfulTypes {
+			// Don't look at code in low-level packages
+			for _, imp := range pass.Pkg.Imports() {
+				if imp.Path() == "syscall" || imp.Path() == "unsafe" {
+					return nil, nil
+				}
+			}
+		}
+
+		fn := func(node ast.Node) {
+			decl := node.(*ast.GenDecl)
+			if decl.Tok != token.VAR {
+				return
+			}
+
+			gen, _ := code.Generator(pass, decl.Pos())
+			if gen == facts.Cgo {
+				// TODO(dh): remove this exception once we can use UsesCgo
+				return
+			}
+
+			// Delay looking up parent AST nodes until we have to
+			checkedDecl := false
+
+		specLoop:
+			for _, spec := range decl.Specs {
+				spec := spec.(*ast.ValueSpec)
+				if spec.Type == nil {
+					continue
+				}
+				if len(spec.Names) != len(spec.Values) {
+					continue
+				}
+				Tlhs := pass.TypesInfo.TypeOf(spec.Type)
+				for i, v := range spec.Values {
+					if !flagHelpfulTypes && spec.Names[i].Name == "_" {
+						continue specLoop
+					}
+					Trhs := pass.TypesInfo.TypeOf(v)
+					if !types.Identical(Tlhs, Trhs) {
+						continue specLoop
+					}
+
+					// Some expressions are untyped and get converted to the lhs type implicitly.
+					// This applies to untyped constants, shift operations with an untyped lhs, and possibly others.
+					//
+					// Check if the type is truly redundant, i.e. if the type on the lhs doesn't match the default type of the untyped constant.
+					tv, err := eval(v)
+					if err != nil {
+						panic(err)
+					}
+					if b, ok := tv.Type.(*types.Basic); ok && (b.Info()&types.IsUntyped) != 0 {
+						if Tlhs != types.Default(b) {
+							// The rhs is untyped and its default type differs from the explicit type on the lhs
+							continue specLoop
+						}
+						switch v := v.(type) {
+						case *ast.Ident:
+							// Only flag named constant rhs if it's a predeclared identifier.
+							// Don't flag other named constants, as the explicit type may aid readability.
+							if pass.TypesInfo.ObjectOf(v).Pkg() != nil && !flagHelpfulTypes {
+								continue specLoop
+							}
+						case *ast.BasicLit:
+							// Do flag basic literals
+						default:
+							// Don't flag untyped rhs expressions unless flagHelpfulTypes is set
+							if !flagHelpfulTypes {
+								continue specLoop
+							}
+						}
+					}
+				}
+
+				if !checkedDecl {
+					// Don't flag global variables. These often have explicit types for godoc's sake.
+					path, _ := astutil.PathEnclosingInterval(code.File(pass, decl), decl.Pos(), decl.Pos())
+				pathLoop:
+					for _, el := range path {
+						switch el.(type) {
+						case *ast.FuncDecl, *ast.FuncLit:
+							checkedDecl = true
+							break pathLoop
+						}
+					}
+					if !checkedDecl {
+						// decl is not inside a function
+						break specLoop
+					}
+				}
+
+				report.Report(pass, spec.Type, fmt.Sprintf("%s omit type %s from declaration; it will be inferred from the right-hand side", verb, report.Render(pass, spec.Type)), report.FilterGenerated(),
+					report.Fixes(edit.Fix("Remove redundant type", edit.Delete(spec.Type))))
+			}
+		}
+		code.Preorder(pass, fn, (*ast.GenDecl)(nil))
+		return nil, nil
+	}
+
+	return &analysis.Analyzer{
+		Run:      fn,
+		Requires: []*analysis.Analyzer{facts.Generated, inspect.Analyzer, facts.TokenFile, facts.Generated},
+	}
+}

vendor/honnef.co/go/tools/internal/sync/sync.go

@@ -0,0 +1,36 @@
+package sync
+
+type Semaphore struct {
+	ch chan struct{}
+}
+
+func NewSemaphore(size int) Semaphore {
+	return Semaphore{
+		ch: make(chan struct{}, size),
+	}
+}
+
+func (sem Semaphore) Acquire() {
+	sem.ch <- struct{}{}
+}
+
+func (sem Semaphore) AcquireMaybe() bool {
+	select {
+	case sem.ch <- struct{}{}:
+		return true
+	default:
+		return false
+	}
+}
+
+func (sem Semaphore) Release() {
+	<-sem.ch
+}
+
+func (sem Semaphore) Len() int {
+	return len(sem.ch)
+}
+
+func (sem Semaphore) Cap() int {
+	return cap(sem.ch)
+}

vendor/honnef.co/go/tools/knowledge/arg.go

@@ -0,0 +1,69 @@
+package knowledge
+
+var Args = map[string]int{
+	"(*encoding/json.Decoder).Decode.v":    0,
+	"(*encoding/json.Encoder).Encode.v":    0,
+	"(*encoding/xml.Decoder).Decode.v":     0,
+	"(*encoding/xml.Encoder).Encode.v":     0,
+	"(*sync.Pool).Put.x":                   0,
+	"(*text/template.Template).Parse.text": 0,
+	"(io.Seeker).Seek.offset":              0,
+	"(time.Time).Sub.u":                    0,
+	"append.elems":                         1,
+	"append.slice":                         0,
+	"bytes.Equal.a":                        0,
+	"bytes.Equal.b":                        1,
+	"encoding/binary.Write.data":           2,
+	"errors.New.text":                      0,
+	"fmt.Fprintf.format":                   1,
+	"fmt.Printf.format":                    0,
+	"fmt.Sprintf.a[0]":                     1,
+	"fmt.Sprintf.format":                   0,
+	"json.Marshal.v":                       0,
+	"json.Unmarshal.v":                     1,
+	"len.v":                                0,
+	"make.size[0]":                         1,
+	"make.size[1]":                         2,
+	"make.t":                               0,
+	"net/url.Parse.rawurl":                 0,
+	"os.OpenFile.flag":                     1,
+	"os/exec.Command.name":                 0,
+	"os/signal.Notify.c":                   0,
+	"regexp.Compile.expr":                  0,
+	"runtime.SetFinalizer.finalizer":       1,
+	"runtime.SetFinalizer.obj":             0,
+	"sort.Sort.data":                       0,
+	"strconv.AppendFloat.bitSize":          4,
+	"strconv.AppendFloat.fmt":              2,
+	"strconv.AppendInt.base":               2,
+	"strconv.AppendUint.base":              2,
+	"strconv.FormatComplex.bitSize":        3,
+	"strconv.FormatComplex.fmt":            1,
+	"strconv.FormatFloat.bitSize":          3,
+	"strconv.FormatFloat.fmt":              1,
+	"strconv.FormatInt.base":               1,
+	"strconv.FormatUint.base":              1,
+	"strconv.ParseComplex.bitSize":         1,
+	"strconv.ParseFloat.bitSize":           1,
+	"strconv.ParseInt.base":                1,
+	"strconv.ParseInt.bitSize":             2,
+	"strconv.ParseUint.base":               1,
+	"strconv.ParseUint.bitSize":            2,
+	"time.Parse.layout":                    0,
+	"time.Sleep.d":                         0,
+	"xml.Marshal.v":                        0,
+	"xml.Unmarshal.v":                      1,
+}
+
+// Arg turns the name of an argument into an argument index.
+// Indices are zero-based and method receivers do not count as arguments.
+//
+// Arg refers to a manually compiled mapping (see the Args variable.)
+// Modify the knowledge package to add new arguments.
+func Arg(name string) int {
+	n, ok := Args[name]
+	if !ok {
+		panic("unknown argument " + name)
+	}
+	return n
+}

vendor/honnef.co/go/tools/knowledge/deprecated.go

@@ -0,0 +1,253 @@
+package knowledge
+
+const (
+	// DeprecatedNeverUse indicates that an API should never be used, regardless of Go version.
+	DeprecatedNeverUse = -1
+	// DeprecatedUseNoLonger indicates that an API has no use anymore.
+	DeprecatedUseNoLonger = -2
+)
+
+// Deprecation describes when a Go API has been deprecated.
+type Deprecation struct {
+	// The minor Go version since which this API has been deprecated.
+	DeprecatedSince int
+	// The minor Go version since which an alternative API has been available.
+	// May also be one of DeprecatedNeverUse or DeprecatedUseNoLonger.
+	AlternativeAvailableSince int
+}
+
+// go/importer.ForCompiler contains "Deprecated:", but it refers to a single argument, not the whole function.
+// Luckily, the notice starts in the middle of a paragraph, and as such isn't detected by us.
+
+// StdlibDeprecations contains a mapping of Go API (such as variables, methods, or fields, among others)
+// to information about when it has been deprecated.
+var StdlibDeprecations = map[string]Deprecation{
+	// FIXME(dh): AllowBinary isn't being detected as deprecated
+	// because the comment has a newline right after "Deprecated:"
+	"go/build.AllowBinary":                      {7, 7},
+	"(archive/zip.FileHeader).CompressedSize":   {1, 1},
+	"(archive/zip.FileHeader).UncompressedSize": {1, 1},
+	"(archive/zip.FileHeader).ModifiedTime":     {10, 10},
+	"(archive/zip.FileHeader).ModifiedDate":     {10, 10},
+	"(*archive/zip.FileHeader).ModTime":         {10, 10},
+	"(*archive/zip.FileHeader).SetModTime":      {10, 10},
+	"(go/doc.Package).Bugs":                     {1, 1},
+	"os.SEEK_SET":                               {7, 7},
+	"os.SEEK_CUR":                               {7, 7},
+	"os.SEEK_END":                               {7, 7},
+	"(net.Dialer).Cancel":                       {7, 7},
+	"runtime.CPUProfile":                        {9, 0},
+	"compress/flate.ReadError":                  {6, DeprecatedUseNoLonger},
+	"compress/flate.WriteError":                 {6, DeprecatedUseNoLonger},
+	"path/filepath.HasPrefix":                   {0, DeprecatedNeverUse},
+	"(net/http.Transport).Dial":                 {7, 7},
+	"(net/http.Transport).DialTLS":              {14, 14},
+	"(*net/http.Transport).CancelRequest":       {6, 5},
+	"net/http.ErrWriteAfterFlush":               {7, DeprecatedUseNoLonger},
+	"net/http.ErrHeaderTooLong":                 {8, DeprecatedUseNoLonger},
+	"net/http.ErrShortBody":                     {8, DeprecatedUseNoLonger},
+	"net/http.ErrMissingContentLength":          {8, DeprecatedUseNoLonger},
+	"net/http/httputil.ErrPersistEOF":           {0, DeprecatedUseNoLonger},
+	"net/http/httputil.ErrClosed":               {0, DeprecatedUseNoLonger},
+	"net/http/httputil.ErrPipeline":             {0, DeprecatedUseNoLonger},
+	"net/http/httputil.ServerConn":              {0, 0},
+	"net/http/httputil.NewServerConn":           {0, 0},
+	"net/http/httputil.ClientConn":              {0, 0},
+	"net/http/httputil.NewClientConn":           {0, 0},
+	"net/http/httputil.NewProxyClientConn":      {0, 0},
+	"(net/http.Request).Cancel":                 {7, 7},
+	"(text/template/parse.PipeNode).Line":       {1, DeprecatedUseNoLonger},
+	"(text/template/parse.ActionNode).Line":     {1, DeprecatedUseNoLonger},
+	"(text/template/parse.BranchNode).Line":     {1, DeprecatedUseNoLonger},
+	"(text/template/parse.TemplateNode).Line":   {1, DeprecatedUseNoLonger},
+	"database/sql/driver.ColumnConverter":       {9, 9},
+	"database/sql/driver.Execer":                {8, 8},
+	"database/sql/driver.Queryer":               {8, 8},
+	"(database/sql/driver.Conn).Begin":          {8, 8},
+	"(database/sql/driver.Stmt).Exec":           {8, 8},
+	"(database/sql/driver.Stmt).Query":          {8, 8},
+	"syscall.StringByteSlice":                   {1, 1},
+	"syscall.StringBytePtr":                     {1, 1},
+	"syscall.StringSlicePtr":                    {1, 1},
+	"syscall.StringToUTF16":                     {1, 1},
+	"syscall.StringToUTF16Ptr":                  {1, 1},
+	"(*regexp.Regexp).Copy":                     {12, DeprecatedUseNoLonger},
+	"(archive/tar.Header).Xattrs":               {10, 10},
+	"archive/tar.TypeRegA":                      {11, 1},
+	"go/types.NewInterface":                     {11, 11},
+	"(*go/types.Interface).Embedded":            {11, 11},
+	"go/importer.For":                           {12, 12},
+	"encoding/json.InvalidUTF8Error":            {2, DeprecatedUseNoLonger},
+	"encoding/json.UnmarshalFieldError":         {2, DeprecatedUseNoLonger},
+	"encoding/csv.ErrTrailingComma":             {2, DeprecatedUseNoLonger},
+	"(encoding/csv.Reader).TrailingComma":       {2, DeprecatedUseNoLonger},
+	"(net.Dialer).DualStack":                    {12, 12},
+	"net/http.ErrUnexpectedTrailer":             {12, DeprecatedUseNoLonger},
+	"net/http.CloseNotifier":                    {11, 7},
+	// This is hairy. The notice says "Not all errors in the http package related to protocol errors are of type ProtocolError", but doesn't that imply that some errors do?
+	"net/http.ProtocolError":                      {8, DeprecatedUseNoLonger},
+	"(crypto/x509.CertificateRequest).Attributes": {5, 3},
+
+	// These functions have no direct alternative, but they are insecure and should no longer be used.
+	"crypto/x509.IsEncryptedPEMBlock": {16, DeprecatedNeverUse},
+	"crypto/x509.DecryptPEMBlock":     {16, DeprecatedNeverUse},
+	"crypto/x509.EncryptPEMBlock":     {16, DeprecatedNeverUse},
+	"crypto/dsa":                      {16, DeprecatedNeverUse},
+
+	// This function has no alternative, but also no purpose.
+	"(*crypto/rc4.Cipher).Reset":                     {12, DeprecatedNeverUse},
+	"(net/http/httptest.ResponseRecorder).HeaderMap": {11, 7},
+	"image.ZP":                                    {13, 0},
+	"image.ZR":                                    {13, 0},
+	"(*debug/gosym.LineTable).LineToPC":           {2, 2},
+	"(*debug/gosym.LineTable).PCToLine":           {2, 2},
+	"crypto/tls.VersionSSL30":                     {13, DeprecatedNeverUse},
+	"(crypto/tls.Config).NameToCertificate":       {14, DeprecatedUseNoLonger},
+	"(*crypto/tls.Config).BuildNameToCertificate": {14, DeprecatedUseNoLonger},
+	"(crypto/tls.Config).SessionTicketKey":        {16, 5},
+	// No alternative, no use
+	"(crypto/tls.ConnectionState).NegotiatedProtocolIsMutual": {16, DeprecatedNeverUse},
+	// No alternative, but insecure
+	"(crypto/tls.ConnectionState).TLSUnique": {16, DeprecatedNeverUse},
+	"image/jpeg.Reader":                      {4, DeprecatedNeverUse},
+
+	// All of these have been deprecated in favour of external libraries
+	"syscall.AttachLsf":                     {7, 0},
+	"syscall.DetachLsf":                     {7, 0},
+	"syscall.LsfSocket":                     {7, 0},
+	"syscall.SetLsfPromisc":                 {7, 0},
+	"syscall.LsfJump":                       {7, 0},
+	"syscall.LsfStmt":                       {7, 0},
+	"syscall.BpfStmt":                       {7, 0},
+	"syscall.BpfJump":                       {7, 0},
+	"syscall.BpfBuflen":                     {7, 0},
+	"syscall.SetBpfBuflen":                  {7, 0},
+	"syscall.BpfDatalink":                   {7, 0},
+	"syscall.SetBpfDatalink":                {7, 0},
+	"syscall.SetBpfPromisc":                 {7, 0},
+	"syscall.FlushBpf":                      {7, 0},
+	"syscall.BpfInterface":                  {7, 0},
+	"syscall.SetBpfInterface":               {7, 0},
+	"syscall.BpfTimeout":                    {7, 0},
+	"syscall.SetBpfTimeout":                 {7, 0},
+	"syscall.BpfStats":                      {7, 0},
+	"syscall.SetBpfImmediate":               {7, 0},
+	"syscall.SetBpf":                        {7, 0},
+	"syscall.CheckBpfVersion":               {7, 0},
+	"syscall.BpfHeadercmpl":                 {7, 0},
+	"syscall.SetBpfHeadercmpl":              {7, 0},
+	"syscall.RouteRIB":                      {8, 0},
+	"syscall.RoutingMessage":                {8, 0},
+	"syscall.RouteMessage":                  {8, 0},
+	"syscall.InterfaceMessage":              {8, 0},
+	"syscall.InterfaceAddrMessage":          {8, 0},
+	"syscall.ParseRoutingMessage":           {8, 0},
+	"syscall.ParseRoutingSockaddr":          {8, 0},
+	"syscall.InterfaceAnnounceMessage":      {7, 0},
+	"syscall.InterfaceMulticastAddrMessage": {7, 0},
+	"syscall.FormatMessage":                 {5, 0},
+	"syscall.PostQueuedCompletionStatus":    {17, 0},
+	"syscall.GetQueuedCompletionStatus":     {17, 0},
+	"syscall.CreateIoCompletionPort":        {17, 0},
+
+	// Not marked as deprecated with a recognizable header, but deprecated nonetheless.
+	"io/ioutil": {16, 16},
+
+	"bytes.Title":   {18, 0},
+	"strings.Title": {18, 0},
+	"(crypto/tls.Config).PreferServerCipherSuites": {18, DeprecatedUseNoLonger},
+	// It's not clear if Subjects was okay to use in the past, so we err on the less noisy side of assuming that it was.
+	"(*crypto/x509.CertPool).Subjects": {18, DeprecatedUseNoLonger},
+	"go/types.NewSignature":            {18, 18},
+	"(net.Error).Temporary":            {18, DeprecatedNeverUse},
+	// InterfaceData is another tricky case. It was deprecated in Go 1.18, but has been useless since Go 1.4, and an
+	// "alternative" (using your own unsafe hacks) has existed forever. We don't want to get into hairsplitting with
+	// users who somehow successfully used this between 1.4 and 1.18, so we'll just tag it as deprecated since 1.18.
+	"(reflect.Value).InterfaceData": {18, 18},
+
+	// The following objects are only deprecated on Windows.
+	"syscall.Syscall":   {18, 18},
+	"syscall.Syscall12": {18, 18},
+	"syscall.Syscall15": {18, 18},
+	"syscall.Syscall18": {18, 18},
+	"syscall.Syscall6":  {18, 18},
+	"syscall.Syscall9":  {18, 18},
+}
+
+// Last imported from Go at 4aa1efed4853ea067d665a952eee77c52faac774 with the following numbers of deprecations:
+//
+// archive/tar/common.go:2
+// archive/zip/struct.go:6
+// bytes/bytes.go:1
+// cmd/compile/internal/ir/expr.go:1
+// cmd/compile/internal/ir/type.go:1
+// cmd/compile/internal/syntax/walk.go:1
+// cmd/compile/internal/types/sym.go:2
+// cmd/go/internal/modcmd/edit.go:1
+// cmd/go/testdata/mod/example.com_deprecated_a_v1.9.0.txt:2
+// cmd/go/testdata/mod/example.com_deprecated_b_v1.9.0.txt:2
+// cmd/go/testdata/mod/example.com_undeprecated_v1.0.0.txt:2
+// cmd/go/testdata/script/mod_deprecate_message.txt:4
+// cmd/go/testdata/script/mod_edit.txt:1
+// cmd/go/testdata/script/mod_list_deprecated.txt:2
+// cmd/go/testdata/script/mod_list_deprecated_replace.txt:1
+// cmd/internal/obj/link.go:5
+// cmd/internal/obj/textflag.go:1
+// cmd/vendor/golang.org/x/mod/modfile/rule.go:2
+// cmd/vendor/golang.org/x/mod/semver/semver.go:1
+// cmd/vendor/golang.org/x/sys/unix/zsysnum_darwin_amd64.go:1
+// cmd/vendor/golang.org/x/sys/unix/zsysnum_darwin_arm64.go:1
+// cmd/vendor/golang.org/x/sys/windows/security_windows.go:1
+// cmd/vendor/golang.org/x/sys/windows/syscall_windows.go:2
+// compress/flate/inflate.go:2
+// crypto/dsa/dsa.go:1
+// crypto/rc4/rc4.go:1
+// crypto/tls/common.go:7
+// crypto/x509/cert_pool.go:1
+// crypto/x509/pem_decrypt.go:3
+// crypto/x509/x509.go:1
+// database/sql/driver/driver.go:6
+// debug/gosym/pclntab.go:2
+// encoding/csv/reader.go:2
+// encoding/json/decode.go:1
+// encoding/json/encode.go:1
+// go/doc/doc.go:1
+// go/importer/importer.go:2
+// go/types/errorcodes.go:1
+// go/types/interface.go:2
+// go/types/signature.go:1
+// image/geom.go:2
+// image/jpeg/reader.go:1
+// net/dial.go:2
+// net/http/httptest/recorder.go:1
+// net/http/httputil/persist.go:8
+// net/http/request.go:6
+// net/http/server.go:2
+// net/http/socks_bundle.go:1
+// net/http/transport.go:3
+// net/net.go:1
+// os/file.go:1
+// path/filepath/path_plan9.go:1
+// path/filepath/path_unix.go:1
+// path/filepath/path_windows.go:1
+// reflect/value.go:1
+// regexp/regexp.go:1
+// runtime/cpuprof.go:1
+// strings/strings.go:1
+// syscall/bpf_bsd.go:18
+// syscall/bpf_darwin.go:18
+// syscall/dll_windows.go:6
+// syscall/exec_plan9.go:1
+// syscall/exec_unix.go:1
+// syscall/lsf_linux.go:6
+// syscall/route_bsd.go:7
+// syscall/route_darwin.go:1
+// syscall/route_dragonfly.go:2
+// syscall/route_freebsd.go:2
+// syscall/route_netbsd.go:1
+// syscall/route_openbsd.go:1
+// syscall/syscall.go:3
+// syscall/syscall_windows.go:6
+// text/template/parse/node.go:5
+// vendor/golang.org/x/crypto/curve25519/curve25519.go:1
+// vendor/golang.org/x/text/transform/transform.go:1

vendor/honnef.co/go/tools/knowledge/doc.go

@@ -0,0 +1,2 @@
+// Package knowledge contains manually collected information about Go APIs.
+package knowledge

vendor/honnef.co/go/tools/lintcmd/cache/UPSTREAM

@@ -0,0 +1,10 @@
+This package is a copy of cmd/go/internal/cache.
+
+Differences from upstream:
+- we continue to use renameio instead of lockedfile for writing trim.txt
+- we still use I/O helpers that work with earlier versions of Go.
+- we use a cache directory specific to Staticcheck
+- we use a Staticcheck-specific salt
+
+The last upstream commit we've looked at was:
+06ac303f6a14b133254f757e54599c48e3c2a4ad

vendor/honnef.co/go/tools/lintcmd/cache/cache.go

@@ -0,0 +1,533 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package cache implements a build artifact cache.
+//
+// This package is a slightly modified fork of Go's
+// cmd/go/internal/cache package.
+package cache
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"honnef.co/go/tools/internal/renameio"
+)
+
+// An ActionID is a cache action key, the hash of a complete description of a
+// repeatable computation (command line, environment variables,
+// input file contents, executable contents).
+type ActionID [HashSize]byte
+
+// An OutputID is a cache output key, the hash of an output of a computation.
+type OutputID [HashSize]byte
+
+// A Cache is a package cache, backed by a file system directory tree.
+type Cache struct {
+	dir  string
+	now  func() time.Time
+	salt []byte
+}
+
+// Open opens and returns the cache in the given directory.
+//
+// It is safe for multiple processes on a single machine to use the
+// same cache directory in a local file system simultaneously.
+// They will coordinate using operating system file locks and may
+// duplicate effort but will not corrupt the cache.
+//
+// However, it is NOT safe for multiple processes on different machines
+// to share a cache directory (for example, if the directory were stored
+// in a network file system). File locking is notoriously unreliable in
+// network file systems and may not suffice to protect the cache.
+//
+func Open(dir string) (*Cache, error) {
+	info, err := os.Stat(dir)
+	if err != nil {
+		return nil, err
+	}
+	if !info.IsDir() {
+		return nil, &os.PathError{Op: "open", Path: dir, Err: fmt.Errorf("not a directory")}
+	}
+	for i := 0; i < 256; i++ {
+		name := filepath.Join(dir, fmt.Sprintf("%02x", i))
+		if err := os.MkdirAll(name, 0777); err != nil {
+			return nil, err
+		}
+	}
+	c := &Cache{
+		dir: dir,
+		now: time.Now,
+	}
+	return c, nil
+}
+
+func (c *Cache) SetSalt(b []byte) {
+	c.salt = b
+}
+
+// fileName returns the name of the file corresponding to the given id.
+func (c *Cache) fileName(id [HashSize]byte, key string) string {
+	return filepath.Join(c.dir, fmt.Sprintf("%02x", id[0]), fmt.Sprintf("%x", id)+"-"+key)
+}
+
+// An entryNotFoundError indicates that a cache entry was not found, with an
+// optional underlying reason.
+type entryNotFoundError struct {
+	Err error
+}
+
+func (e *entryNotFoundError) Error() string {
+	if e.Err == nil {
+		return "cache entry not found"
+	}
+	return fmt.Sprintf("cache entry not found: %v", e.Err)
+}
+
+func (e *entryNotFoundError) Unwrap() error {
+	return e.Err
+}
+
+const (
+	// action entry file is "v1 <hex id> <hex out> <decimal size space-padded to 20 bytes> <unixnano space-padded to 20 bytes>\n"
+	hexSize   = HashSize * 2
+	entrySize = 2 + 1 + hexSize + 1 + hexSize + 1 + 20 + 1 + 20 + 1
+)
+
+// verify controls whether to run the cache in verify mode.
+// In verify mode, the cache always returns errMissing from Get
+// but then double-checks in Put that the data being written
+// exactly matches any existing entry. This provides an easy
+// way to detect program behavior that would have been different
+// had the cache entry been returned from Get.
+//
+// verify is enabled by setting the environment variable
+// GODEBUG=gocacheverify=1.
+var verify = false
+
+var errVerifyMode = errors.New("gocacheverify=1")
+
+// DebugTest is set when GODEBUG=gocachetest=1 is in the environment.
+var DebugTest = false
+
+func init() { initEnv() }
+
+func initEnv() {
+	verify = false
+	debugHash = false
+	debug := strings.Split(os.Getenv("GODEBUG"), ",")
+	for _, f := range debug {
+		if f == "gocacheverify=1" {
+			verify = true
+		}
+		if f == "gocachehash=1" {
+			debugHash = true
+		}
+		if f == "gocachetest=1" {
+			DebugTest = true
+		}
+	}
+}
+
+// Get looks up the action ID in the cache,
+// returning the corresponding output ID and file size, if any.
+// Note that finding an output ID does not guarantee that the
+// saved file for that output ID is still available.
+func (c *Cache) Get(id ActionID) (Entry, error) {
+	if verify {
+		return Entry{}, &entryNotFoundError{Err: errVerifyMode}
+	}
+	return c.get(id)
+}
+
+type Entry struct {
+	OutputID OutputID
+	Size     int64
+	Time     time.Time
+}
+
+// get is Get but does not respect verify mode, so that Put can use it.
+func (c *Cache) get(id ActionID) (Entry, error) {
+	missing := func(reason error) (Entry, error) {
+		return Entry{}, &entryNotFoundError{Err: reason}
+	}
+	f, err := os.Open(c.fileName(id, "a"))
+	if err != nil {
+		return missing(err)
+	}
+	defer f.Close()
+	entry := make([]byte, entrySize+1) // +1 to detect whether f is too long
+	if n, err := io.ReadFull(f, entry); n > entrySize {
+		return missing(errors.New("too long"))
+	} else if err != io.ErrUnexpectedEOF {
+		if err == io.EOF {
+			return missing(errors.New("file is empty"))
+		}
+		return missing(err)
+	} else if n < entrySize {
+		return missing(errors.New("entry file incomplete"))
+	}
+	if entry[0] != 'v' || entry[1] != '1' || entry[2] != ' ' || entry[3+hexSize] != ' ' || entry[3+hexSize+1+hexSize] != ' ' || entry[3+hexSize+1+hexSize+1+20] != ' ' || entry[entrySize-1] != '\n' {
+		return missing(errors.New("invalid header"))
+	}
+	eid, entry := entry[3:3+hexSize], entry[3+hexSize:]
+	eout, entry := entry[1:1+hexSize], entry[1+hexSize:]
+	esize, entry := entry[1:1+20], entry[1+20:]
+	//lint:ignore SA4006 See https://github.com/dominikh/go-tools/issues/465
+	etime, entry := entry[1:1+20], entry[1+20:]
+	var buf [HashSize]byte
+	if _, err := hex.Decode(buf[:], eid); err != nil {
+		return missing(fmt.Errorf("decoding ID: %v", err))
+	} else if buf != id {
+		return missing(errors.New("mismatched ID"))
+	}
+	if _, err := hex.Decode(buf[:], eout); err != nil {
+		return missing(fmt.Errorf("decoding output ID: %v", err))
+	}
+	i := 0
+	for i < len(esize) && esize[i] == ' ' {
+		i++
+	}
+	size, err := strconv.ParseInt(string(esize[i:]), 10, 64)
+	if err != nil {
+		return missing(fmt.Errorf("parsing size: %v", err))
+	} else if size < 0 {
+		return missing(errors.New("negative size"))
+	}
+	i = 0
+	for i < len(etime) && etime[i] == ' ' {
+		i++
+	}
+	tm, err := strconv.ParseInt(string(etime[i:]), 10, 64)
+	if err != nil {
+		return missing(fmt.Errorf("parsing timestamp: %v", err))
+	} else if tm < 0 {
+		return missing(errors.New("negative timestamp"))
+	}
+
+	c.used(c.fileName(id, "a"))
+
+	return Entry{buf, size, time.Unix(0, tm)}, nil
+}
+
+// GetFile looks up the action ID in the cache and returns
+// the name of the corresponding data file.
+func (c *Cache) GetFile(id ActionID) (file string, entry Entry, err error) {
+	entry, err = c.Get(id)
+	if err != nil {
+		return "", Entry{}, err
+	}
+	file = c.OutputFile(entry.OutputID)
+	info, err := os.Stat(file)
+	if err != nil {
+		return "", Entry{}, &entryNotFoundError{Err: err}
+	}
+	if info.Size() != entry.Size {
+		return "", Entry{}, &entryNotFoundError{Err: errors.New("file incomplete")}
+	}
+	return file, entry, nil
+}
+
+// GetBytes looks up the action ID in the cache and returns
+// the corresponding output bytes.
+// GetBytes should only be used for data that can be expected to fit in memory.
+func (c *Cache) GetBytes(id ActionID) ([]byte, Entry, error) {
+	entry, err := c.Get(id)
+	if err != nil {
+		return nil, entry, err
+	}
+	data, _ := ioutil.ReadFile(c.OutputFile(entry.OutputID))
+	if sha256.Sum256(data) != entry.OutputID {
+		return nil, entry, &entryNotFoundError{Err: errors.New("bad checksum")}
+	}
+	return data, entry, nil
+}
+
+// OutputFile returns the name of the cache file storing output with the given OutputID.
+func (c *Cache) OutputFile(out OutputID) string {
+	file := c.fileName(out, "d")
+	c.used(file)
+	return file
+}
+
+// Time constants for cache expiration.
+//
+// We set the mtime on a cache file on each use, but at most one per mtimeInterval (1 hour),
+// to avoid causing many unnecessary inode updates. The mtimes therefore
+// roughly reflect "time of last use" but may in fact be older by at most an hour.
+//
+// We scan the cache for entries to delete at most once per trimInterval (1 day).
+//
+// When we do scan the cache, we delete entries that have not been used for
+// at least trimLimit (5 days). Statistics gathered from a month of usage by
+// Go developers found that essentially all reuse of cached entries happened
+// within 5 days of the previous reuse. See golang.org/issue/22990.
+const (
+	mtimeInterval = 1 * time.Hour
+	trimInterval  = 24 * time.Hour
+	trimLimit     = 5 * 24 * time.Hour
+)
+
+// used makes a best-effort attempt to update mtime on file,
+// so that mtime reflects cache access time.
+//
+// Because the reflection only needs to be approximate,
+// and to reduce the amount of disk activity caused by using
+// cache entries, used only updates the mtime if the current
+// mtime is more than an hour old. This heuristic eliminates
+// nearly all of the mtime updates that would otherwise happen,
+// while still keeping the mtimes useful for cache trimming.
+func (c *Cache) used(file string) {
+	info, err := os.Stat(file)
+	if err == nil && c.now().Sub(info.ModTime()) < mtimeInterval {
+		return
+	}
+	os.Chtimes(file, c.now(), c.now())
+}
+
+// Trim removes old cache entries that are likely not to be reused.
+func (c *Cache) Trim() {
+	now := c.now()
+
+	// We maintain in dir/trim.txt the time of the last completed cache trim.
+	// If the cache has been trimmed recently enough, do nothing.
+	// This is the common case.
+	data, _ := renameio.ReadFile(filepath.Join(c.dir, "trim.txt"))
+	t, err := strconv.ParseInt(strings.TrimSpace(string(data)), 10, 64)
+	if err == nil && now.Sub(time.Unix(t, 0)) < trimInterval {
+		return
+	}
+
+	// Trim each of the 256 subdirectories.
+	// We subtract an additional mtimeInterval
+	// to account for the imprecision of our "last used" mtimes.
+	cutoff := now.Add(-trimLimit - mtimeInterval)
+	for i := 0; i < 256; i++ {
+		subdir := filepath.Join(c.dir, fmt.Sprintf("%02x", i))
+		c.trimSubdir(subdir, cutoff)
+	}
+
+	// Ignore errors from here: if we don't write the complete timestamp, the
+	// cache will appear older than it is, and we'll trim it again next time.
+	renameio.WriteFile(filepath.Join(c.dir, "trim.txt"), []byte(fmt.Sprintf("%d", now.Unix())), 0666)
+}
+
+// trimSubdir trims a single cache subdirectory.
+func (c *Cache) trimSubdir(subdir string, cutoff time.Time) {
+	// Read all directory entries from subdir before removing
+	// any files, in case removing files invalidates the file offset
+	// in the directory scan. Also, ignore error from f.Readdirnames,
+	// because we don't care about reporting the error and we still
+	// want to process any entries found before the error.
+	f, err := os.Open(subdir)
+	if err != nil {
+		return
+	}
+	names, _ := f.Readdirnames(-1)
+	f.Close()
+
+	for _, name := range names {
+		// Remove only cache entries (xxxx-a and xxxx-d).
+		if !strings.HasSuffix(name, "-a") && !strings.HasSuffix(name, "-d") {
+			continue
+		}
+		entry := filepath.Join(subdir, name)
+		info, err := os.Stat(entry)
+		if err == nil && info.ModTime().Before(cutoff) {
+			os.Remove(entry)
+		}
+	}
+}
+
+// putIndexEntry adds an entry to the cache recording that executing the action
+// with the given id produces an output with the given output id (hash) and size.
+func (c *Cache) putIndexEntry(id ActionID, out OutputID, size int64, allowVerify bool) error {
+	// Note: We expect that for one reason or another it may happen
+	// that repeating an action produces a different output hash
+	// (for example, if the output contains a time stamp or temp dir name).
+	// While not ideal, this is also not a correctness problem, so we
+	// don't make a big deal about it. In particular, we leave the action
+	// cache entries writable specifically so that they can be overwritten.
+	//
+	// Setting GODEBUG=gocacheverify=1 does make a big deal:
+	// in verify mode we are double-checking that the cache entries
+	// are entirely reproducible. As just noted, this may be unrealistic
+	// in some cases but the check is also useful for shaking out real bugs.
+	entry := fmt.Sprintf("v1 %x %x %20d %20d\n", id, out, size, time.Now().UnixNano())
+	if verify && allowVerify {
+		old, err := c.get(id)
+		if err == nil && (old.OutputID != out || old.Size != size) {
+			// panic to show stack trace, so we can see what code is generating this cache entry.
+			msg := fmt.Sprintf("go: internal cache error: cache verify failed: id=%x changed:<<<\n%s\n>>>\nold: %x %d\nnew: %x %d", id, reverseHash(id), out, size, old.OutputID, old.Size)
+			panic(msg)
+		}
+	}
+	file := c.fileName(id, "a")
+
+	// Copy file to cache directory.
+	mode := os.O_WRONLY | os.O_CREATE
+	f, err := os.OpenFile(file, mode, 0666)
+	if err != nil {
+		return err
+	}
+	_, err = f.WriteString(entry)
+	if err == nil {
+		// Truncate the file only *after* writing it.
+		// (This should be a no-op, but truncate just in case of previous corruption.)
+		//
+		// This differs from ioutil.WriteFile, which truncates to 0 *before* writing
+		// via os.O_TRUNC. Truncating only after writing ensures that a second write
+		// of the same content to the same file is idempotent, and does not — even
+		// temporarily! — undo the effect of the first write.
+		err = f.Truncate(int64(len(entry)))
+	}
+	if closeErr := f.Close(); err == nil {
+		err = closeErr
+	}
+	if err != nil {
+		// TODO(bcmills): This Remove potentially races with another go command writing to file.
+		// Can we eliminate it?
+		os.Remove(file)
+		return err
+	}
+	os.Chtimes(file, c.now(), c.now()) // mainly for tests
+
+	return nil
+}
+
+// Put stores the given output in the cache as the output for the action ID.
+// It may read file twice. The content of file must not change between the two passes.
+func (c *Cache) Put(id ActionID, file io.ReadSeeker) (OutputID, int64, error) {
+	return c.put(id, file, true)
+}
+
+// PutNoVerify is like Put but disables the verify check
+// when GODEBUG=goverifycache=1 is set.
+// It is meant for data that is OK to cache but that we expect to vary slightly from run to run,
+// like test output containing times and the like.
+func (c *Cache) PutNoVerify(id ActionID, file io.ReadSeeker) (OutputID, int64, error) {
+	return c.put(id, file, false)
+}
+
+func (c *Cache) put(id ActionID, file io.ReadSeeker, allowVerify bool) (OutputID, int64, error) {
+	// Compute output ID.
+	h := sha256.New()
+	if _, err := file.Seek(0, 0); err != nil {
+		return OutputID{}, 0, err
+	}
+	size, err := io.Copy(h, file)
+	if err != nil {
+		return OutputID{}, 0, err
+	}
+	var out OutputID
+	h.Sum(out[:0])
+
+	// Copy to cached output file (if not already present).
+	if err := c.copyFile(file, out, size); err != nil {
+		return out, size, err
+	}
+
+	// Add to cache index.
+	return out, size, c.putIndexEntry(id, out, size, allowVerify)
+}
+
+// PutBytes stores the given bytes in the cache as the output for the action ID.
+func (c *Cache) PutBytes(id ActionID, data []byte) error {
+	_, _, err := c.Put(id, bytes.NewReader(data))
+	return err
+}
+
+// copyFile copies file into the cache, expecting it to have the given
+// output ID and size, if that file is not present already.
+func (c *Cache) copyFile(file io.ReadSeeker, out OutputID, size int64) error {
+	name := c.fileName(out, "d")
+	info, err := os.Stat(name)
+	if err == nil && info.Size() == size {
+		// Check hash.
+		if f, err := os.Open(name); err == nil {
+			h := sha256.New()
+			io.Copy(h, f)
+			f.Close()
+			var out2 OutputID
+			h.Sum(out2[:0])
+			if out == out2 {
+				return nil
+			}
+		}
+		// Hash did not match. Fall through and rewrite file.
+	}
+
+	// Copy file to cache directory.
+	mode := os.O_RDWR | os.O_CREATE
+	if err == nil && info.Size() > size { // shouldn't happen but fix in case
+		mode |= os.O_TRUNC
+	}
+	f, err := os.OpenFile(name, mode, 0666)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	if size == 0 {
+		// File now exists with correct size.
+		// Only one possible zero-length file, so contents are OK too.
+		// Early return here makes sure there's a "last byte" for code below.
+		return nil
+	}
+
+	// From here on, if any of the I/O writing the file fails,
+	// we make a best-effort attempt to truncate the file f
+	// before returning, to avoid leaving bad bytes in the file.
+
+	// Copy file to f, but also into h to double-check hash.
+	if _, err := file.Seek(0, 0); err != nil {
+		f.Truncate(0)
+		return err
+	}
+	h := sha256.New()
+	w := io.MultiWriter(f, h)
+	if _, err := io.CopyN(w, file, size-1); err != nil {
+		f.Truncate(0)
+		return err
+	}
+	// Check last byte before writing it; writing it will make the size match
+	// what other processes expect to find and might cause them to start
+	// using the file.
+	buf := make([]byte, 1)
+	if _, err := file.Read(buf); err != nil {
+		f.Truncate(0)
+		return err
+	}
+	h.Write(buf)
+	sum := h.Sum(nil)
+	if !bytes.Equal(sum, out[:]) {
+		f.Truncate(0)
+		return fmt.Errorf("file content changed underfoot")
+	}
+
+	// Commit cache file entry.
+	if _, err := f.Write(buf); err != nil {
+		f.Truncate(0)
+		return err
+	}
+	if err := f.Close(); err != nil {
+		// Data might not have been written,
+		// but file may look like it is the right size.
+		// To be extra careful, remove cached file.
+		os.Remove(name)
+		return err
+	}
+	os.Chtimes(name, c.now(), c.now()) // mainly for tests
+
+	return nil
+}

vendor/honnef.co/go/tools/lintcmd/cache/default.go

@@ -0,0 +1,85 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cache
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+// Default returns the default cache to use.
+func Default() (*Cache, error) {
+	defaultOnce.Do(initDefaultCache)
+	return defaultCache, defaultDirErr
+}
+
+var (
+	defaultOnce  sync.Once
+	defaultCache *Cache
+)
+
+// cacheREADME is a message stored in a README in the cache directory.
+// Because the cache lives outside the normal Go trees, we leave the
+// README as a courtesy to explain where it came from.
+const cacheREADME = `This directory holds cached build artifacts from staticcheck.
+`
+
+// initDefaultCache does the work of finding the default cache
+// the first time Default is called.
+func initDefaultCache() {
+	dir := DefaultDir()
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		log.Fatalf("failed to initialize build cache at %s: %s\n", dir, err)
+	}
+	if _, err := os.Stat(filepath.Join(dir, "README")); err != nil {
+		// Best effort.
+		ioutil.WriteFile(filepath.Join(dir, "README"), []byte(cacheREADME), 0666)
+	}
+
+	c, err := Open(dir)
+	if err != nil {
+		log.Fatalf("failed to initialize build cache at %s: %s\n", dir, err)
+	}
+	defaultCache = c
+}
+
+var (
+	defaultDirOnce sync.Once
+	defaultDir     string
+	defaultDirErr  error
+)
+
+// DefaultDir returns the effective STATICCHECK_CACHE setting.
+func DefaultDir() string {
+	// Save the result of the first call to DefaultDir for later use in
+	// initDefaultCache. cmd/go/main.go explicitly sets GOCACHE so that
+	// subprocesses will inherit it, but that means initDefaultCache can't
+	// otherwise distinguish between an explicit "off" and a UserCacheDir error.
+
+	defaultDirOnce.Do(func() {
+		defaultDir = os.Getenv("STATICCHECK_CACHE")
+		if filepath.IsAbs(defaultDir) {
+			return
+		}
+		if defaultDir != "" {
+			defaultDirErr = fmt.Errorf("STATICCHECK_CACHE is not an absolute path")
+			return
+		}
+
+		// Compute default location.
+		dir, err := os.UserCacheDir()
+		if err != nil {
+			defaultDirErr = fmt.Errorf("STATICCHECK_CACHE is not defined and %v", err)
+			return
+		}
+		defaultDir = filepath.Join(dir, "staticcheck")
+	})
+
+	return defaultDir
+}

vendor/honnef.co/go/tools/lintcmd/cache/hash.go

@@ -0,0 +1,163 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cache
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"fmt"
+	"hash"
+	"io"
+	"os"
+	"sync"
+)
+
+var debugHash = false // set when GODEBUG=gocachehash=1
+
+// HashSize is the number of bytes in a hash.
+const HashSize = 32
+
+// A Hash provides access to the canonical hash function used to index the cache.
+// The current implementation uses salted SHA256, but clients must not assume this.
+type Hash struct {
+	h    hash.Hash
+	name string        // for debugging
+	buf  *bytes.Buffer // for verify
+}
+
+// Subkey returns an action ID corresponding to mixing a parent
+// action ID with a string description of the subkey.
+func Subkey(parent ActionID, desc string) ActionID {
+	h := sha256.New()
+	h.Write([]byte("subkey:"))
+	h.Write(parent[:])
+	h.Write([]byte(desc))
+	var out ActionID
+	h.Sum(out[:0])
+	if debugHash {
+		fmt.Fprintf(os.Stderr, "HASH subkey %x %q = %x\n", parent, desc, out)
+	}
+	if verify {
+		hashDebug.Lock()
+		hashDebug.m[out] = fmt.Sprintf("subkey %x %q", parent, desc)
+		hashDebug.Unlock()
+	}
+	return out
+}
+
+// NewHash returns a new Hash.
+// The caller is expected to Write data to it and then call Sum.
+func (c *Cache) NewHash(name string) *Hash {
+	h := &Hash{h: sha256.New(), name: name}
+	if debugHash {
+		fmt.Fprintf(os.Stderr, "HASH[%s]\n", h.name)
+	}
+	h.Write(c.salt)
+	if verify {
+		h.buf = new(bytes.Buffer)
+	}
+	return h
+}
+
+// Write writes data to the running hash.
+func (h *Hash) Write(b []byte) (int, error) {
+	if debugHash {
+		fmt.Fprintf(os.Stderr, "HASH[%s]: %q\n", h.name, b)
+	}
+	if h.buf != nil {
+		h.buf.Write(b)
+	}
+	return h.h.Write(b)
+}
+
+// Sum returns the hash of the data written previously.
+func (h *Hash) Sum() [HashSize]byte {
+	var out [HashSize]byte
+	h.h.Sum(out[:0])
+	if debugHash {
+		fmt.Fprintf(os.Stderr, "HASH[%s]: %x\n", h.name, out)
+	}
+	if h.buf != nil {
+		hashDebug.Lock()
+		if hashDebug.m == nil {
+			hashDebug.m = make(map[[HashSize]byte]string)
+		}
+		hashDebug.m[out] = h.buf.String()
+		hashDebug.Unlock()
+	}
+	return out
+}
+
+// In GODEBUG=gocacheverify=1 mode,
+// hashDebug holds the input to every computed hash ID,
+// so that we can work backward from the ID involved in a
+// cache entry mismatch to a description of what should be there.
+var hashDebug struct {
+	sync.Mutex
+	m map[[HashSize]byte]string
+}
+
+// reverseHash returns the input used to compute the hash id.
+func reverseHash(id [HashSize]byte) string {
+	hashDebug.Lock()
+	s := hashDebug.m[id]
+	hashDebug.Unlock()
+	return s
+}
+
+var hashFileCache struct {
+	sync.Mutex
+	m map[string][HashSize]byte
+}
+
+// FileHash returns the hash of the named file.
+// It caches repeated lookups for a given file,
+// and the cache entry for a file can be initialized
+// using SetFileHash.
+// The hash used by FileHash is not the same as
+// the hash used by NewHash.
+func FileHash(file string) ([HashSize]byte, error) {
+	hashFileCache.Lock()
+	out, ok := hashFileCache.m[file]
+	hashFileCache.Unlock()
+
+	if ok {
+		return out, nil
+	}
+
+	h := sha256.New()
+	f, err := os.Open(file)
+	if err != nil {
+		if debugHash {
+			fmt.Fprintf(os.Stderr, "HASH %s: %v\n", file, err)
+		}
+		return [HashSize]byte{}, err
+	}
+	_, err = io.Copy(h, f)
+	f.Close()
+	if err != nil {
+		if debugHash {
+			fmt.Fprintf(os.Stderr, "HASH %s: %v\n", file, err)
+		}
+		return [HashSize]byte{}, err
+	}
+	h.Sum(out[:0])
+	if debugHash {
+		fmt.Fprintf(os.Stderr, "HASH %s: %x\n", file, out)
+	}
+
+	SetFileHash(file, out)
+	return out, nil
+}
+
+// SetFileHash sets the hash returned by FileHash for file.
+func SetFileHash(file string, sum [HashSize]byte) {
+	hashFileCache.Lock()
+	if hashFileCache.m == nil {
+		hashFileCache.m = make(map[string][HashSize]byte)
+	}
+	hashFileCache.m[file] = sum
+	hashFileCache.Unlock()
+}

vendor/honnef.co/go/tools/lintcmd/cmd.go

@@ -0,0 +1,742 @@
+// Package lintcmd implements the frontend of an analysis runner.
+// It serves as the entry-point for the staticcheck command, and can also be used to implement custom linters that behave like staticcheck.
+package lintcmd
+
+import (
+	"bufio"
+	"encoding/gob"
+	"flag"
+	"fmt"
+	"go/token"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"reflect"
+	"runtime"
+	"runtime/pprof"
+	"runtime/trace"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/config"
+	"honnef.co/go/tools/go/loader"
+	"honnef.co/go/tools/lintcmd/version"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/buildutil"
+)
+
+type BuildConfig struct {
+	Name  string
+	Envs  []string
+	Flags []string
+}
+
+// Command represents a linter command line tool.
+type Command struct {
+	name           string
+	analyzers      map[string]*lint.Analyzer
+	version        string
+	machineVersion string
+
+	flags struct {
+		fs *flag.FlagSet
+
+		tags        string
+		tests       bool
+		showIgnored bool
+		formatter   string
+
+		// mutually exclusive mode flags
+		explain      string
+		printVersion bool
+		listChecks   bool
+		merge        bool
+
+		matrix bool
+
+		debugCpuprofile       string
+		debugMemprofile       string
+		debugVersion          bool
+		debugNoCompileErrors  bool
+		debugMeasureAnalyzers string
+		debugTrace            string
+
+		checks    list
+		fail      list
+		goVersion versionFlag
+	}
+}
+
+// NewCommand returns a new Command.
+func NewCommand(name string) *Command {
+	cmd := &Command{
+		name:           name,
+		analyzers:      map[string]*lint.Analyzer{},
+		version:        "devel",
+		machineVersion: "devel",
+	}
+	cmd.initFlagSet(name)
+	return cmd
+}
+
+// SetVersion sets the command's version.
+// It is divided into a human part and a machine part.
+// For example, Staticcheck 2020.2.1 had the human version "2020.2.1" and the machine version "v0.1.1".
+// If you only use Semver, you can set both parts to the same value.
+//
+// Calling this method is optional. Both versions default to "devel", and we'll attempt to deduce more version information from the Go module.
+func (cmd *Command) SetVersion(human, machine string) {
+	cmd.version = human
+	cmd.machineVersion = machine
+}
+
+// FlagSet returns the command's flag set.
+// This can be used to add additional command line arguments.
+func (cmd *Command) FlagSet() *flag.FlagSet {
+	return cmd.flags.fs
+}
+
+// AddAnalyzers adds analyzers to the command.
+// These are lint.Analyzer analyzers, which wrap analysis.Analyzer analyzers, bundling them with structured documentation.
+//
+// To add analysis.Analyzer analyzers without providing structured documentation, use AddBareAnalyzers.
+func (cmd *Command) AddAnalyzers(as ...*lint.Analyzer) {
+	for _, a := range as {
+		cmd.analyzers[a.Analyzer.Name] = a
+	}
+}
+
+// AddBareAnalyzers adds bare analyzers to the command.
+func (cmd *Command) AddBareAnalyzers(as ...*analysis.Analyzer) {
+	for _, a := range as {
+		var title, text string
+		if idx := strings.Index(a.Doc, "\n\n"); idx > -1 {
+			title = a.Doc[:idx]
+			text = a.Doc[idx+2:]
+		}
+
+		doc := &lint.Documentation{
+			Title:    title,
+			Text:     text,
+			Severity: lint.SeverityWarning,
+		}
+
+		cmd.analyzers[a.Name] = &lint.Analyzer{
+			Doc:      doc,
+			Analyzer: a,
+		}
+	}
+}
+
+func (cmd *Command) initFlagSet(name string) {
+	flags := flag.NewFlagSet("", flag.ExitOnError)
+	cmd.flags.fs = flags
+	flags.Usage = usage(name, flags)
+
+	flags.StringVar(&cmd.flags.tags, "tags", "", "List of `build tags`")
+	flags.BoolVar(&cmd.flags.tests, "tests", true, "Include tests")
+	flags.BoolVar(&cmd.flags.printVersion, "version", false, "Print version and exit")
+	flags.BoolVar(&cmd.flags.showIgnored, "show-ignored", false, "Don't filter ignored diagnostics")
+	flags.StringVar(&cmd.flags.formatter, "f", "text", "Output `format` (valid choices are 'stylish', 'text' and 'json')")
+	flags.StringVar(&cmd.flags.explain, "explain", "", "Print description of `check`")
+	flags.BoolVar(&cmd.flags.listChecks, "list-checks", false, "List all available checks")
+	flags.BoolVar(&cmd.flags.merge, "merge", false, "Merge results of multiple Staticcheck runs")
+	flags.BoolVar(&cmd.flags.matrix, "matrix", false, "Read a build config matrix from stdin")
+
+	flags.StringVar(&cmd.flags.debugCpuprofile, "debug.cpuprofile", "", "Write CPU profile to `file`")
+	flags.StringVar(&cmd.flags.debugMemprofile, "debug.memprofile", "", "Write memory profile to `file`")
+	flags.BoolVar(&cmd.flags.debugVersion, "debug.version", false, "Print detailed version information about this program")
+	flags.BoolVar(&cmd.flags.debugNoCompileErrors, "debug.no-compile-errors", false, "Don't print compile errors")
+	flags.StringVar(&cmd.flags.debugMeasureAnalyzers, "debug.measure-analyzers", "", "Write analysis measurements to `file`. `file` will be opened for appending if it already exists.")
+	flags.StringVar(&cmd.flags.debugTrace, "debug.trace", "", "Write trace to `file`")
+
+	cmd.flags.checks = list{"inherit"}
+	cmd.flags.fail = list{"all"}
+	cmd.flags.goVersion = versionFlag("module")
+	flags.Var(&cmd.flags.checks, "checks", "Comma-separated list of `checks` to enable.")
+	flags.Var(&cmd.flags.fail, "fail", "Comma-separated list of `checks` that can cause a non-zero exit status.")
+	flags.Var(&cmd.flags.goVersion, "go", "Target Go `version` in the format '1.x', or the literal 'module' to use the module's Go version")
+}
+
+type list []string
+
+func (list *list) String() string {
+	return `"` + strings.Join(*list, ",") + `"`
+}
+
+func (list *list) Set(s string) error {
+	if s == "" {
+		*list = nil
+		return nil
+	}
+
+	elems := strings.Split(s, ",")
+	for i, elem := range elems {
+		elems[i] = strings.TrimSpace(elem)
+	}
+	*list = elems
+	return nil
+}
+
+type versionFlag string
+
+func (v *versionFlag) String() string {
+	return fmt.Sprintf("%q", string(*v))
+}
+
+func (v *versionFlag) Set(s string) error {
+	if s == "module" {
+		*v = "module"
+	} else {
+		var vf lint.VersionFlag
+		if err := vf.Set(s); err != nil {
+			return err
+		}
+		*v = versionFlag(s)
+	}
+	return nil
+}
+
+// ParseFlags parses command line flags.
+// It must be called before calling Run.
+// After calling ParseFlags, the values of flags can be accessed.
+//
+// Example:
+//
+// 	cmd.ParseFlags(os.Args[1:])
+func (cmd *Command) ParseFlags(args []string) {
+	cmd.flags.fs.Parse(args)
+}
+
+// diagnosticDescriptor represents the uniquiely identifying information of diagnostics.
+type diagnosticDescriptor struct {
+	Position token.Position
+	End      token.Position
+	Category string
+	Message  string
+}
+
+func (diag diagnostic) descriptor() diagnosticDescriptor {
+	return diagnosticDescriptor{
+		Position: diag.Position,
+		End:      diag.End,
+		Category: diag.Category,
+		Message:  diag.Message,
+	}
+}
+
+type run struct {
+	checkedFiles map[string]struct{}
+	diagnostics  map[diagnosticDescriptor]diagnostic
+}
+
+func runFromLintResult(res LintResult) run {
+	out := run{
+		checkedFiles: map[string]struct{}{},
+		diagnostics:  map[diagnosticDescriptor]diagnostic{},
+	}
+
+	for _, cf := range res.CheckedFiles {
+		out.checkedFiles[cf] = struct{}{}
+	}
+	for _, diag := range res.Diagnostics {
+		out.diagnostics[diag.descriptor()] = diag
+	}
+	return out
+}
+
+func decodeGob(br io.ByteReader) ([]run, error) {
+	var runs []run
+	for {
+		var res LintResult
+		if err := gob.NewDecoder(br.(io.Reader)).Decode(&res); err != nil {
+			if err == io.EOF {
+				break
+			} else {
+				return nil, err
+			}
+		}
+		runs = append(runs, runFromLintResult(res))
+	}
+	return runs, nil
+}
+
+// Run runs all registered analyzers and reports their findings.
+// It always calls os.Exit and does not return.
+func (cmd *Command) Run() {
+	var measureAnalyzers func(analysis *analysis.Analyzer, pkg *loader.PackageSpec, d time.Duration)
+	if path := cmd.flags.debugMeasureAnalyzers; path != "" {
+		f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		mu := &sync.Mutex{}
+		measureAnalyzers = func(analysis *analysis.Analyzer, pkg *loader.PackageSpec, d time.Duration) {
+			mu.Lock()
+			defer mu.Unlock()
+			// FIXME(dh): print pkg.ID
+			if _, err := fmt.Fprintf(f, "%s\t%s\t%d\n", analysis.Name, pkg, d.Nanoseconds()); err != nil {
+				log.Println("error writing analysis measurements:", err)
+			}
+		}
+	}
+
+	if path := cmd.flags.debugCpuprofile; path != "" {
+		f, err := os.Create(path)
+		if err != nil {
+			log.Fatal(err)
+		}
+		pprof.StartCPUProfile(f)
+	}
+	if path := cmd.flags.debugTrace; path != "" {
+		f, err := os.Create(path)
+		if err != nil {
+			log.Fatal(err)
+		}
+		trace.Start(f)
+	}
+
+	defaultChecks := []string{"all"}
+	cs := make([]*lint.Analyzer, 0, len(cmd.analyzers))
+	for _, a := range cmd.analyzers {
+		cs = append(cs, a)
+		if a.Doc.NonDefault {
+			defaultChecks = append(defaultChecks, "-"+a.Analyzer.Name)
+		}
+	}
+	config.DefaultConfig.Checks = defaultChecks
+
+	switch {
+	case cmd.flags.debugVersion:
+		version.Verbose(cmd.version, cmd.machineVersion)
+		cmd.exit(0)
+	case cmd.flags.listChecks:
+		sort.Slice(cs, func(i, j int) bool {
+			return cs[i].Analyzer.Name < cs[j].Analyzer.Name
+		})
+		for _, c := range cs {
+			var title string
+			if c.Doc != nil {
+				title = c.Doc.Title
+			}
+			fmt.Printf("%s %s\n", c.Analyzer.Name, title)
+		}
+		cmd.exit(0)
+	case cmd.flags.printVersion:
+		version.Print(cmd.version, cmd.machineVersion)
+		cmd.exit(0)
+	case cmd.flags.explain != "":
+		explain := cmd.flags.explain
+		check, ok := cmd.analyzers[explain]
+		if !ok {
+			fmt.Fprintln(os.Stderr, "Couldn't find check", explain)
+			cmd.exit(1)
+		}
+		if check.Analyzer.Doc == "" {
+			fmt.Fprintln(os.Stderr, explain, "has no documentation")
+			cmd.exit(1)
+		}
+		fmt.Println(check.Doc)
+		fmt.Println("Online documentation\n    https://staticcheck.io/docs/checks#" + check.Analyzer.Name)
+		cmd.exit(0)
+	case cmd.flags.merge:
+		var runs []run
+		if len(cmd.flags.fs.Args()) == 0 {
+			var err error
+			runs, err = decodeGob(bufio.NewReader(os.Stdin))
+			if err != nil {
+				fmt.Fprintln(os.Stderr, fmt.Errorf("couldn't parse stdin: %s", err))
+				cmd.exit(1)
+			}
+		} else {
+			for _, path := range cmd.flags.fs.Args() {
+				someRuns, err := func(path string) ([]run, error) {
+					f, err := os.Open(path)
+					if err != nil {
+						return nil, err
+					}
+					defer f.Close()
+					br := bufio.NewReader(f)
+					return decodeGob(br)
+				}(path)
+				if err != nil {
+					fmt.Fprintln(os.Stderr, fmt.Errorf("couldn't parse file %s: %s", path, err))
+					cmd.exit(1)
+				}
+				runs = append(runs, someRuns...)
+			}
+		}
+
+		relevantDiagnostics := mergeRuns(runs)
+		cmd.printDiagnostics(cs, relevantDiagnostics)
+	default:
+		switch cmd.flags.formatter {
+		case "text", "stylish", "json", "sarif", "binary", "null":
+		default:
+			fmt.Fprintf(os.Stderr, "unsupported output format %q\n", cmd.flags.formatter)
+			cmd.exit(2)
+		}
+
+		var bconfs []BuildConfig
+		if cmd.flags.matrix {
+			if cmd.flags.tags != "" {
+				fmt.Fprintln(os.Stderr, "cannot use -matrix and -tags together")
+				cmd.exit(2)
+			}
+
+			var err error
+			bconfs, err = parseBuildConfigs(os.Stdin)
+			if err != nil {
+				if perr, ok := err.(parseBuildConfigError); ok {
+					fmt.Fprintf(os.Stderr, "<stdin>:%d couldn't parse build matrix: %s\n", perr.line, perr.err)
+				} else {
+					fmt.Fprintln(os.Stderr, err)
+				}
+				os.Exit(2)
+			}
+		} else {
+			bc := BuildConfig{}
+			if cmd.flags.tags != "" {
+				// Validate that the tags argument is well-formed. go/packages
+				// doesn't detect malformed build flags and returns unhelpful
+				// errors.
+				tf := buildutil.TagsFlag{}
+				if err := tf.Set(cmd.flags.tags); err != nil {
+					fmt.Fprintln(os.Stderr, fmt.Errorf("invalid value %q for flag -tags: %s", cmd.flags.tags, err))
+					cmd.exit(1)
+				}
+
+				bc.Flags = []string{"-tags", cmd.flags.tags}
+			}
+			bconfs = append(bconfs, bc)
+		}
+
+		var runs []run
+		for _, bconf := range bconfs {
+			res, err := doLint(cs, cmd.flags.fs.Args(), &options{
+				BuildConfig: bconf,
+				LintTests:   cmd.flags.tests,
+				GoVersion:   string(cmd.flags.goVersion),
+				Config: config.Config{
+					Checks: cmd.flags.checks,
+				},
+				PrintAnalyzerMeasurement: measureAnalyzers,
+			})
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				cmd.exit(1)
+			}
+
+			for _, w := range res.Warnings {
+				fmt.Fprintln(os.Stderr, "warning:", w)
+			}
+
+			cwd, err := os.Getwd()
+			if err != nil {
+				cwd = ""
+			}
+			relPath := func(s string) string {
+				if cwd == "" {
+					return filepath.ToSlash(s)
+				}
+				out, err := filepath.Rel(cwd, s)
+				if err != nil {
+					return filepath.ToSlash(s)
+				}
+				return filepath.ToSlash(out)
+			}
+
+			if cmd.flags.formatter == "binary" {
+				for i, s := range res.CheckedFiles {
+					res.CheckedFiles[i] = relPath(s)
+				}
+				for i := range res.Diagnostics {
+					// We turn all paths into relative, /-separated paths. This is to make -merge work correctly when
+					// merging runs from different OSs, with different absolute paths.
+					//
+					// We zero out Offset, because checkouts of code on different OSs may have different kinds of
+					// newlines and thus different offsets. We don't ever make use of the Offset, anyway. Line and
+					// column numbers are precomputed.
+
+					d := &res.Diagnostics[i]
+					d.Position.Filename = relPath(d.Position.Filename)
+					d.Position.Offset = 0
+					d.End.Filename = relPath(d.End.Filename)
+					d.End.Offset = 0
+					for j := range d.Related {
+						r := &d.Related[j]
+						r.Position.Filename = relPath(r.Position.Filename)
+						r.Position.Offset = 0
+						r.End.Filename = relPath(r.End.Filename)
+						r.End.Offset = 0
+					}
+				}
+				err := gob.NewEncoder(os.Stdout).Encode(res)
+				if err != nil {
+					fmt.Fprintf(os.Stderr, "failed writing output: %s\n", err)
+					cmd.exit(2)
+				}
+			} else {
+				runs = append(runs, runFromLintResult(res))
+			}
+		}
+
+		if cmd.flags.formatter != "binary" {
+			diags := mergeRuns(runs)
+			cmd.printDiagnostics(cs, diags)
+		}
+	}
+}
+
+func mergeRuns(runs []run) []diagnostic {
+	var relevantDiagnostics []diagnostic
+	for _, r := range runs {
+		for _, diag := range r.diagnostics {
+			switch diag.MergeIf {
+			case lint.MergeIfAny:
+				relevantDiagnostics = append(relevantDiagnostics, diag)
+			case lint.MergeIfAll:
+				doPrint := true
+				for _, r := range runs {
+					if _, ok := r.checkedFiles[diag.Position.Filename]; ok {
+						if _, ok := r.diagnostics[diag.descriptor()]; !ok {
+							doPrint = false
+						}
+					}
+				}
+				if doPrint {
+					relevantDiagnostics = append(relevantDiagnostics, diag)
+				}
+			}
+		}
+	}
+	return relevantDiagnostics
+}
+
+func (cmd *Command) exit(code int) {
+	if cmd.flags.debugCpuprofile != "" {
+		pprof.StopCPUProfile()
+	}
+	if path := cmd.flags.debugMemprofile; path != "" {
+		f, err := os.Create(path)
+		if err != nil {
+			panic(err)
+		}
+		runtime.GC()
+		pprof.WriteHeapProfile(f)
+	}
+	if cmd.flags.debugTrace != "" {
+		trace.Stop()
+	}
+	os.Exit(code)
+}
+
+func (cmd *Command) printDiagnostics(cs []*lint.Analyzer, diagnostics []diagnostic) {
+	if len(diagnostics) > 1 {
+		sort.Slice(diagnostics, func(i, j int) bool {
+			di := diagnostics[i]
+			dj := diagnostics[j]
+			pi := di.Position
+			pj := dj.Position
+
+			if pi.Filename != pj.Filename {
+				return pi.Filename < pj.Filename
+			}
+			if pi.Line != pj.Line {
+				return pi.Line < pj.Line
+			}
+			if pi.Column != pj.Column {
+				return pi.Column < pj.Column
+			}
+			if di.Message != dj.Message {
+				return di.Message < dj.Message
+			}
+			if di.BuildName != dj.BuildName {
+				return di.BuildName < dj.BuildName
+			}
+			return di.Category < dj.Category
+		})
+
+		filtered := []diagnostic{
+			diagnostics[0],
+		}
+		builds := []map[string]struct{}{
+			{diagnostics[0].BuildName: {}},
+		}
+		for _, diag := range diagnostics[1:] {
+			// We may encounter duplicate diagnostics because one file
+			// can be part of many packages, and because multiple
+			// build configurations may check the same files.
+			if !filtered[len(filtered)-1].equal(diag) {
+				if filtered[len(filtered)-1].descriptor() == diag.descriptor() {
+					// Diagnostics only differ in build name, track new name
+					builds[len(filtered)-1][diag.BuildName] = struct{}{}
+				} else {
+					filtered = append(filtered, diag)
+					builds = append(builds, map[string]struct{}{})
+					builds[len(filtered)-1][diag.BuildName] = struct{}{}
+				}
+			}
+		}
+
+		var names []string
+		for i := range filtered {
+			names = names[:0]
+			for k := range builds[i] {
+				names = append(names, k)
+			}
+			sort.Strings(names)
+			filtered[i].BuildName = strings.Join(names, ",")
+		}
+		diagnostics = filtered
+	}
+
+	var f formatter
+	switch cmd.flags.formatter {
+	case "text":
+		f = textFormatter{W: os.Stdout}
+	case "stylish":
+		f = &stylishFormatter{W: os.Stdout}
+	case "json":
+		f = jsonFormatter{W: os.Stdout}
+	case "sarif":
+		f = &sarifFormatter{
+			driverName:    cmd.name,
+			driverVersion: cmd.version,
+		}
+		if cmd.name == "staticcheck" {
+			f.(*sarifFormatter).driverName = "Staticcheck"
+			f.(*sarifFormatter).driverWebsite = "https://staticcheck.io"
+		}
+	case "binary":
+		fmt.Fprintln(os.Stderr, "'-f binary' not supported in this context")
+		cmd.exit(2)
+	case "null":
+		f = nullFormatter{}
+	default:
+		fmt.Fprintf(os.Stderr, "unsupported output format %q\n", cmd.flags.formatter)
+		cmd.exit(2)
+	}
+
+	fail := cmd.flags.fail
+	analyzerNames := make([]string, len(cs))
+	for i, a := range cs {
+		analyzerNames[i] = a.Analyzer.Name
+	}
+	shouldExit := filterAnalyzerNames(analyzerNames, fail)
+	shouldExit["staticcheck"] = true
+	shouldExit["compile"] = true
+
+	var (
+		numErrors   int
+		numWarnings int
+		numIgnored  int
+	)
+	notIgnored := make([]diagnostic, 0, len(diagnostics))
+	for _, diag := range diagnostics {
+		if diag.Category == "compile" && cmd.flags.debugNoCompileErrors {
+			continue
+		}
+		if diag.Severity == severityIgnored && !cmd.flags.showIgnored {
+			numIgnored++
+			continue
+		}
+		if shouldExit[diag.Category] {
+			numErrors++
+		} else {
+			diag.Severity = severityWarning
+			numWarnings++
+		}
+		notIgnored = append(notIgnored, diag)
+	}
+
+	f.Format(cs, notIgnored)
+	if f, ok := f.(statter); ok {
+		f.Stats(len(diagnostics), numErrors, numWarnings, numIgnored)
+	}
+
+	if numErrors > 0 {
+		if _, ok := f.(*sarifFormatter); ok {
+			// When emitting SARIF, finding errors is considered success.
+			cmd.exit(0)
+		} else {
+			cmd.exit(1)
+		}
+	}
+	cmd.exit(0)
+}
+
+func usage(name string, fs *flag.FlagSet) func() {
+	return func() {
+		fmt.Fprintf(os.Stderr, "Usage: %s [flags] [packages]\n", name)
+
+		fmt.Fprintln(os.Stderr)
+		fmt.Fprintln(os.Stderr, "Flags:")
+		printDefaults(fs)
+
+		fmt.Fprintln(os.Stderr)
+		fmt.Fprintln(os.Stderr, "For help about specifying packages, see 'go help packages'")
+	}
+}
+
+// isZeroValue determines whether the string represents the zero
+// value for a flag.
+//
+// this function has been copied from the Go standard library's 'flag' package.
+func isZeroValue(f *flag.Flag, value string) bool {
+	// Build a zero value of the flag's Value type, and see if the
+	// result of calling its String method equals the value passed in.
+	// This works unless the Value type is itself an interface type.
+	typ := reflect.TypeOf(f.Value)
+	var z reflect.Value
+	if typ.Kind() == reflect.Ptr {
+		z = reflect.New(typ.Elem())
+	} else {
+		z = reflect.Zero(typ)
+	}
+	return value == z.Interface().(flag.Value).String()
+}
+
+// this function has been copied from the Go standard library's 'flag' package and modified to skip debug flags.
+func printDefaults(fs *flag.FlagSet) {
+	fs.VisitAll(func(f *flag.Flag) {
+		// Don't print debug flags
+		if strings.HasPrefix(f.Name, "debug.") {
+			return
+		}
+
+		var b strings.Builder
+		fmt.Fprintf(&b, "  -%s", f.Name) // Two spaces before -; see next two comments.
+		name, usage := flag.UnquoteUsage(f)
+		if len(name) > 0 {
+			b.WriteString(" ")
+			b.WriteString(name)
+		}
+		// Boolean flags of one ASCII letter are so common we
+		// treat them specially, putting their usage on the same line.
+		if b.Len() <= 4 { // space, space, '-', 'x'.
+			b.WriteString("\t")
+		} else {
+			// Four spaces before the tab triggers good alignment
+			// for both 4- and 8-space tab stops.
+			b.WriteString("\n    \t")
+		}
+		b.WriteString(strings.ReplaceAll(usage, "\n", "\n    \t"))
+
+		if !isZeroValue(f, f.DefValue) {
+			if T := reflect.TypeOf(f.Value); T.Name() == "*stringValue" && T.PkgPath() == "flag" {
+				// put quotes on the value
+				fmt.Fprintf(&b, " (default %q)", f.DefValue)
+			} else {
+				fmt.Fprintf(&b, " (default %v)", f.DefValue)
+			}
+		}
+		fmt.Fprint(fs.Output(), b.String(), "\n")
+	})
+}

vendor/honnef.co/go/tools/lintcmd/config.go

@@ -0,0 +1,105 @@
+package lintcmd
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+	"unicode"
+)
+
+type parseBuildConfigError struct {
+	line int
+	err  error
+}
+
+func (err parseBuildConfigError) Error() string { return err.err.Error() }
+
+func parseBuildConfigs(r io.Reader) ([]BuildConfig, error) {
+	var builds []BuildConfig
+	br := bufio.NewReader(r)
+	i := 0
+	for {
+		line, err := br.ReadString('\n')
+		if err != nil {
+			if err == io.EOF {
+				break
+			} else {
+				return nil, err
+			}
+		}
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		name, envs, flags, err := parseBuildConfig(line)
+		if err != nil {
+			return nil, parseBuildConfigError{line: i + 1, err: err}
+		}
+
+		bc := BuildConfig{
+			Name:  name,
+			Envs:  envs,
+			Flags: flags,
+		}
+		builds = append(builds, bc)
+
+		i++
+	}
+	return builds, nil
+}
+
+func parseBuildConfig(line string) (name string, envs []string, flags []string, err error) {
+	if line == "" {
+		return "", nil, nil, errors.New("couldn't parse empty build config")
+	}
+	if strings.Index(line, ":") == len(line)-1 {
+		name = line[:len(line)-1]
+	} else {
+		idx := strings.Index(line, ": ")
+		if idx == -1 {
+			return name, envs, flags, errors.New("missing build name")
+		}
+		name = line[:idx]
+
+		var buf []rune
+		var inQuote bool
+		args := &envs
+		for _, r := range strings.TrimSpace(line[idx+2:]) {
+			switch r {
+			case ' ':
+				if inQuote {
+					buf = append(buf, r)
+				} else if len(buf) != 0 {
+					if buf[0] == '-' {
+						args = &flags
+					}
+					*args = append(*args, string(buf))
+					buf = buf[:0]
+				}
+			case '"':
+				inQuote = !inQuote
+			default:
+				buf = append(buf, r)
+			}
+		}
+
+		if len(buf) > 0 {
+			if inQuote {
+				return "", nil, nil, errors.New("unterminated quoted string")
+			}
+			if buf[0] == '-' {
+				args = &flags
+			}
+			*args = append(*args, string(buf))
+		}
+	}
+
+	for _, r := range name {
+		if !(r == '_' || unicode.IsLetter(r) || unicode.IsNumber(r)) {
+			return "", nil, nil, fmt.Errorf("invalid build name %q", name)
+		}
+	}
+	return name, envs, flags, nil
+}

vendor/honnef.co/go/tools/lintcmd/directives.go

@@ -0,0 +1,55 @@
+package lintcmd
+
+import (
+	"strings"
+
+	"honnef.co/go/tools/lintcmd/runner"
+)
+
+func parseDirectives(dirs []runner.SerializedDirective) ([]ignore, []diagnostic) {
+	var ignores []ignore
+	var diagnostics []diagnostic
+
+	for _, dir := range dirs {
+		cmd := dir.Command
+		args := dir.Arguments
+		switch cmd {
+		case "ignore", "file-ignore":
+			if len(args) < 2 {
+				p := diagnostic{
+					Diagnostic: runner.Diagnostic{
+						Position: dir.NodePosition,
+						Message:  "malformed linter directive; missing the required reason field?",
+						Category: "compile",
+					},
+					Severity: severityError,
+				}
+				diagnostics = append(diagnostics, p)
+				continue
+			}
+		default:
+			// unknown directive, ignore
+			continue
+		}
+		checks := strings.Split(args[0], ",")
+		pos := dir.NodePosition
+		var ig ignore
+		switch cmd {
+		case "ignore":
+			ig = &lineIgnore{
+				File:   pos.Filename,
+				Line:   pos.Line,
+				Checks: checks,
+				Pos:    dir.DirectivePosition,
+			}
+		case "file-ignore":
+			ig = &fileIgnore{
+				File:   pos.Filename,
+				Checks: checks,
+			}
+		}
+		ignores = append(ignores, ig)
+	}
+
+	return ignores, diagnostics
+}

vendor/honnef.co/go/tools/lintcmd/format.go

@@ -0,0 +1,161 @@
+package lintcmd
+
+import (
+	"encoding/json"
+	"fmt"
+	"go/token"
+	"io"
+	"os"
+	"path/filepath"
+	"text/tabwriter"
+
+	"honnef.co/go/tools/analysis/lint"
+)
+
+func shortPath(path string) string {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return path
+	}
+	if rel, err := filepath.Rel(cwd, path); err == nil && len(rel) < len(path) {
+		return rel
+	}
+	return path
+}
+
+func relativePositionString(pos token.Position) string {
+	s := shortPath(pos.Filename)
+	if pos.IsValid() {
+		if s != "" {
+			s += ":"
+		}
+		s += fmt.Sprintf("%d:%d", pos.Line, pos.Column)
+	}
+	if s == "" {
+		s = "-"
+	}
+	return s
+}
+
+type statter interface {
+	Stats(total, errors, warnings, ignored int)
+}
+
+type formatter interface {
+	Format(checks []*lint.Analyzer, diagnostics []diagnostic)
+}
+
+type textFormatter struct {
+	W io.Writer
+}
+
+func (o textFormatter) Format(_ []*lint.Analyzer, ps []diagnostic) {
+	for _, p := range ps {
+		fmt.Fprintf(o.W, "%s: %s\n", relativePositionString(p.Position), p.String())
+		for _, r := range p.Related {
+			fmt.Fprintf(o.W, "\t%s: %s\n", relativePositionString(r.Position), r.Message)
+		}
+	}
+}
+
+type nullFormatter struct{}
+
+func (nullFormatter) Format([]*lint.Analyzer, []diagnostic) {}
+
+type jsonFormatter struct {
+	W io.Writer
+}
+
+func (o jsonFormatter) Format(_ []*lint.Analyzer, ps []diagnostic) {
+	type location struct {
+		File   string `json:"file"`
+		Line   int    `json:"line"`
+		Column int    `json:"column"`
+	}
+	type related struct {
+		Location location `json:"location"`
+		End      location `json:"end"`
+		Message  string   `json:"message"`
+	}
+
+	enc := json.NewEncoder(o.W)
+	for _, p := range ps {
+		jp := struct {
+			Code     string    `json:"code"`
+			Severity string    `json:"severity,omitempty"`
+			Location location  `json:"location"`
+			End      location  `json:"end"`
+			Message  string    `json:"message"`
+			Related  []related `json:"related,omitempty"`
+		}{
+			Code:     p.Category,
+			Severity: p.Severity.String(),
+			Location: location{
+				File:   p.Position.Filename,
+				Line:   p.Position.Line,
+				Column: p.Position.Column,
+			},
+			End: location{
+				File:   p.End.Filename,
+				Line:   p.End.Line,
+				Column: p.End.Column,
+			},
+			Message: p.Message,
+		}
+		for _, r := range p.Related {
+			jp.Related = append(jp.Related, related{
+				Location: location{
+					File:   r.Position.Filename,
+					Line:   r.Position.Line,
+					Column: r.Position.Column,
+				},
+				End: location{
+					File:   r.End.Filename,
+					Line:   r.End.Line,
+					Column: r.End.Column,
+				},
+				Message: r.Message,
+			})
+		}
+		_ = enc.Encode(jp)
+	}
+}
+
+type stylishFormatter struct {
+	W io.Writer
+
+	prevFile string
+	tw       *tabwriter.Writer
+}
+
+func (o *stylishFormatter) Format(_ []*lint.Analyzer, ps []diagnostic) {
+	for _, p := range ps {
+		pos := p.Position
+		if pos.Filename == "" {
+			pos.Filename = "-"
+		}
+
+		if pos.Filename != o.prevFile {
+			if o.prevFile != "" {
+				o.tw.Flush()
+				fmt.Fprintln(o.W)
+			}
+			fmt.Fprintln(o.W, pos.Filename)
+			o.prevFile = pos.Filename
+			o.tw = tabwriter.NewWriter(o.W, 0, 4, 2, ' ', 0)
+		}
+		fmt.Fprintf(o.tw, "  (%d, %d)\t%s\t%s\n", pos.Line, pos.Column, p.Category, p.Message)
+		for _, r := range p.Related {
+			fmt.Fprintf(o.tw, "    (%d, %d)\t\t  %s\n", r.Position.Line, r.Position.Column, r.Message)
+		}
+	}
+}
+
+func (o *stylishFormatter) Stats(total, errors, warnings, ignored int) {
+	if o.tw != nil {
+		o.tw.Flush()
+		fmt.Fprintln(o.W)
+	}
+	fmt.Fprintf(o.W, " ✖ %d problems (%d errors, %d warnings, %d ignored)\n",
+		total, errors, warnings, ignored)
+}

vendor/honnef.co/go/tools/lintcmd/lint.go

@@ -0,0 +1,577 @@
+package lintcmd
+
+import (
+	"crypto/sha256"
+	"fmt"
+	"go/build"
+	"go/token"
+	"io"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+	"unicode"
+
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/config"
+	"honnef.co/go/tools/go/buildid"
+	"honnef.co/go/tools/go/loader"
+	"honnef.co/go/tools/lintcmd/cache"
+	"honnef.co/go/tools/lintcmd/runner"
+	"honnef.co/go/tools/unused"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/packages"
+)
+
+// A linter lints Go source code.
+type linter struct {
+	Analyzers map[string]*lint.Analyzer
+	Runner    *runner.Runner
+}
+
+func computeSalt() ([]byte, error) {
+	p, err := os.Executable()
+	if err != nil {
+		return nil, err
+	}
+
+	if id, err := buildid.ReadFile(p); err == nil {
+		return []byte(id), nil
+	} else {
+		// For some reason we couldn't read the build id from the executable.
+		// Fall back to hashing the entire executable.
+		f, err := os.Open(p)
+		if err != nil {
+			return nil, err
+		}
+		defer f.Close()
+		h := sha256.New()
+		if _, err := io.Copy(h, f); err != nil {
+			return nil, err
+		}
+		return h.Sum(nil), nil
+	}
+}
+
+func newLinter(cfg config.Config) (*linter, error) {
+	c, err := cache.Default()
+	if err != nil {
+		return nil, err
+	}
+	salt, err := computeSalt()
+	if err != nil {
+		return nil, fmt.Errorf("could not compute salt for cache: %s", err)
+	}
+	c.SetSalt(salt)
+	r, err := runner.New(cfg, c)
+	if err != nil {
+		return nil, err
+	}
+	r.FallbackGoVersion = defaultGoVersion()
+	return &linter{
+		Runner: r,
+	}, nil
+}
+
+type LintResult struct {
+	CheckedFiles []string
+	Diagnostics  []diagnostic
+	Warnings     []string
+}
+
+func (l *linter) Lint(cfg *packages.Config, patterns []string) (LintResult, error) {
+	var out LintResult
+
+	as := make([]*analysis.Analyzer, 0, len(l.Analyzers))
+	for _, a := range l.Analyzers {
+		as = append(as, a.Analyzer)
+	}
+	results, err := l.Runner.Run(cfg, as, patterns)
+	if err != nil {
+		return out, err
+	}
+
+	if len(results) == 0 {
+		// TODO(dh): emulate Go's behavior more closely once we have
+		// access to go list's Match field.
+		for _, pattern := range patterns {
+			fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+		}
+	}
+
+	analyzerNames := make([]string, 0, len(l.Analyzers))
+	for name := range l.Analyzers {
+		analyzerNames = append(analyzerNames, name)
+	}
+	used := map[unusedKey]bool{}
+	var unuseds []unusedPair
+	for _, res := range results {
+		if len(res.Errors) > 0 && !res.Failed {
+			panic("package has errors but isn't marked as failed")
+		}
+		if res.Failed {
+			out.Diagnostics = append(out.Diagnostics, failed(res)...)
+		} else {
+			if res.Skipped {
+				out.Warnings = append(out.Warnings, fmt.Sprintf("skipped package %s because it is too large", res.Package))
+				continue
+			}
+
+			if !res.Initial {
+				continue
+			}
+
+			out.CheckedFiles = append(out.CheckedFiles, res.Package.GoFiles...)
+			allowedAnalyzers := filterAnalyzerNames(analyzerNames, res.Config.Checks)
+			resd, err := res.Load()
+			if err != nil {
+				return out, err
+			}
+			ps := success(allowedAnalyzers, resd)
+			filtered, err := filterIgnored(ps, resd, allowedAnalyzers)
+			if err != nil {
+				return out, err
+			}
+			// OPT move this code into the 'success' function.
+			for i, diag := range filtered {
+				a := l.Analyzers[diag.Category]
+				// Some diag.Category don't map to analyzers, such as "staticcheck"
+				if a != nil {
+					filtered[i].MergeIf = a.Doc.MergeIf
+				}
+			}
+			out.Diagnostics = append(out.Diagnostics, filtered...)
+
+			for _, obj := range resd.Unused.Used {
+				// FIXME(dh): pick the object whose filename does not include $GOROOT
+				key := unusedKey{
+					pkgPath: res.Package.PkgPath,
+					base:    filepath.Base(obj.Position.Filename),
+					line:    obj.Position.Line,
+					name:    obj.Name,
+				}
+				used[key] = true
+			}
+
+			if allowedAnalyzers["U1000"] {
+				for _, obj := range resd.Unused.Unused {
+					key := unusedKey{
+						pkgPath: res.Package.PkgPath,
+						base:    filepath.Base(obj.Position.Filename),
+						line:    obj.Position.Line,
+						name:    obj.Name,
+					}
+					unuseds = append(unuseds, unusedPair{key, obj})
+					if _, ok := used[key]; !ok {
+						used[key] = false
+					}
+				}
+			}
+		}
+	}
+
+	for _, uo := range unuseds {
+		if uo.obj.Kind == "type param" {
+			// We don't currently flag unused type parameters on used objects, and flagging them on unused objects isn't
+			// useful.
+			continue
+		}
+		if used[uo.key] {
+			continue
+		}
+		if uo.obj.InGenerated {
+			continue
+		}
+		out.Diagnostics = append(out.Diagnostics, diagnostic{
+			Diagnostic: runner.Diagnostic{
+				Position: uo.obj.DisplayPosition,
+				Message:  fmt.Sprintf("%s %s is unused", uo.obj.Kind, uo.obj.Name),
+				Category: "U1000",
+			},
+			MergeIf: lint.MergeIfAll,
+		})
+	}
+
+	return out, nil
+}
+
+func filterIgnored(diagnostics []diagnostic, res runner.ResultData, allowedAnalyzers map[string]bool) ([]diagnostic, error) {
+	couldHaveMatched := func(ig *lineIgnore) bool {
+		for _, c := range ig.Checks {
+			if c == "U1000" {
+				// We never want to flag ignores for U1000,
+				// because U1000 isn't local to a single
+				// package. For example, an identifier may
+				// only be used by tests, in which case an
+				// ignore would only fire when not analyzing
+				// tests. To avoid spurious "useless ignore"
+				// warnings, just never flag U1000.
+				return false
+			}
+
+			// Even though the runner always runs all analyzers, we
+			// still only flag unmatched ignores for the set of
+			// analyzers the user has expressed interest in. That way,
+			// `staticcheck -checks=SA1000` won't complain about an
+			// unmatched ignore for an unrelated check.
+			if allowedAnalyzers[c] {
+				return true
+			}
+		}
+
+		return false
+	}
+
+	ignores, moreDiagnostics := parseDirectives(res.Directives)
+
+	for _, ig := range ignores {
+		for i := range diagnostics {
+			diag := &diagnostics[i]
+			if ig.Match(*diag) {
+				diag.Severity = severityIgnored
+			}
+		}
+
+		if ig, ok := ig.(*lineIgnore); ok && !ig.Matched && couldHaveMatched(ig) {
+			diag := diagnostic{
+				Diagnostic: runner.Diagnostic{
+					Position: ig.Pos,
+					Message:  "this linter directive didn't match anything; should it be removed?",
+					Category: "staticcheck",
+				},
+			}
+			moreDiagnostics = append(moreDiagnostics, diag)
+		}
+	}
+
+	return append(diagnostics, moreDiagnostics...), nil
+}
+
+type ignore interface {
+	Match(diag diagnostic) bool
+}
+
+type lineIgnore struct {
+	File    string
+	Line    int
+	Checks  []string
+	Matched bool
+	Pos     token.Position
+}
+
+func (li *lineIgnore) Match(p diagnostic) bool {
+	pos := p.Position
+	if pos.Filename != li.File || pos.Line != li.Line {
+		return false
+	}
+	for _, c := range li.Checks {
+		if m, _ := filepath.Match(c, p.Category); m {
+			li.Matched = true
+			return true
+		}
+	}
+	return false
+}
+
+func (li *lineIgnore) String() string {
+	matched := "not matched"
+	if li.Matched {
+		matched = "matched"
+	}
+	return fmt.Sprintf("%s:%d %s (%s)", li.File, li.Line, strings.Join(li.Checks, ", "), matched)
+}
+
+type fileIgnore struct {
+	File   string
+	Checks []string
+}
+
+func (fi *fileIgnore) Match(p diagnostic) bool {
+	if p.Position.Filename != fi.File {
+		return false
+	}
+	for _, c := range fi.Checks {
+		if m, _ := filepath.Match(c, p.Category); m {
+			return true
+		}
+	}
+	return false
+}
+
+type severity uint8
+
+const (
+	severityError severity = iota
+	severityWarning
+	severityIgnored
+)
+
+func (s severity) String() string {
+	switch s {
+	case severityError:
+		return "error"
+	case severityWarning:
+		return "warning"
+	case severityIgnored:
+		return "ignored"
+	default:
+		return fmt.Sprintf("Severity(%d)", s)
+	}
+}
+
+// diagnostic represents a diagnostic in some source code.
+type diagnostic struct {
+	runner.Diagnostic
+	Severity  severity
+	MergeIf   lint.MergeStrategy
+	BuildName string
+}
+
+func (p diagnostic) equal(o diagnostic) bool {
+	return p.Position == o.Position &&
+		p.End == o.End &&
+		p.Message == o.Message &&
+		p.Category == o.Category &&
+		p.Severity == o.Severity &&
+		p.MergeIf == o.MergeIf &&
+		p.BuildName == o.BuildName
+}
+
+func (p *diagnostic) String() string {
+	if p.BuildName != "" {
+		return fmt.Sprintf("%s [%s] (%s)", p.Message, p.BuildName, p.Category)
+	} else {
+		return fmt.Sprintf("%s (%s)", p.Message, p.Category)
+	}
+}
+
+func failed(res runner.Result) []diagnostic {
+	var diagnostics []diagnostic
+
+	for _, e := range res.Errors {
+		switch e := e.(type) {
+		case packages.Error:
+			msg := e.Msg
+			if len(msg) != 0 && msg[0] == '\n' {
+				// TODO(dh): See https://github.com/golang/go/issues/32363
+				msg = msg[1:]
+			}
+
+			var posn token.Position
+			if e.Pos == "" {
+				// Under certain conditions (malformed package
+				// declarations, multiple packages in the same
+				// directory), go list emits an error on stderr
+				// instead of JSON. Those errors do not have
+				// associated position information in
+				// go/packages.Error, even though the output on
+				// stderr may contain it.
+				if p, n, err := parsePos(msg); err == nil {
+					if abs, err := filepath.Abs(p.Filename); err == nil {
+						p.Filename = abs
+					}
+					posn = p
+					msg = msg[n+2:]
+				}
+			} else {
+				var err error
+				posn, _, err = parsePos(e.Pos)
+				if err != nil {
+					panic(fmt.Sprintf("internal error: %s", e))
+				}
+			}
+			diag := diagnostic{
+				Diagnostic: runner.Diagnostic{
+					Position: posn,
+					Message:  msg,
+					Category: "compile",
+				},
+				Severity: severityError,
+			}
+			diagnostics = append(diagnostics, diag)
+		case error:
+			diag := diagnostic{
+				Diagnostic: runner.Diagnostic{
+					Position: token.Position{},
+					Message:  e.Error(),
+					Category: "compile",
+				},
+				Severity: severityError,
+			}
+			diagnostics = append(diagnostics, diag)
+		}
+	}
+
+	return diagnostics
+}
+
+type unusedKey struct {
+	pkgPath string
+	base    string
+	line    int
+	name    string
+}
+
+type unusedPair struct {
+	key unusedKey
+	obj unused.SerializedObject
+}
+
+func success(allowedAnalyzers map[string]bool, res runner.ResultData) []diagnostic {
+	diags := res.Diagnostics
+	var diagnostics []diagnostic
+	for _, diag := range diags {
+		if !allowedAnalyzers[diag.Category] {
+			continue
+		}
+		diagnostics = append(diagnostics, diagnostic{Diagnostic: diag})
+	}
+	return diagnostics
+}
+
+func defaultGoVersion() string {
+	tags := build.Default.ReleaseTags
+	v := tags[len(tags)-1][2:]
+	return v
+}
+
+func filterAnalyzerNames(analyzers []string, checks []string) map[string]bool {
+	allowedChecks := map[string]bool{}
+
+	for _, check := range checks {
+		b := true
+		if len(check) > 1 && check[0] == '-' {
+			b = false
+			check = check[1:]
+		}
+		if check == "*" || check == "all" {
+			// Match all
+			for _, c := range analyzers {
+				allowedChecks[c] = b
+			}
+		} else if strings.HasSuffix(check, "*") {
+			// Glob
+			prefix := check[:len(check)-1]
+			isCat := strings.IndexFunc(prefix, func(r rune) bool { return unicode.IsNumber(r) }) == -1
+
+			for _, a := range analyzers {
+				idx := strings.IndexFunc(a, func(r rune) bool { return unicode.IsNumber(r) })
+				if isCat {
+					// Glob is S*, which should match S1000 but not SA1000
+					cat := a[:idx]
+					if prefix == cat {
+						allowedChecks[a] = b
+					}
+				} else {
+					// Glob is S1*
+					if strings.HasPrefix(a, prefix) {
+						allowedChecks[a] = b
+					}
+				}
+			}
+		} else {
+			// Literal check name
+			allowedChecks[check] = b
+		}
+	}
+	return allowedChecks
+}
+
+var posRe = regexp.MustCompile(`^(.+?):(\d+)(?::(\d+)?)?`)
+
+func parsePos(pos string) (token.Position, int, error) {
+	if pos == "-" || pos == "" {
+		return token.Position{}, 0, nil
+	}
+	parts := posRe.FindStringSubmatch(pos)
+	if parts == nil {
+		return token.Position{}, 0, fmt.Errorf("internal error: malformed position %q", pos)
+	}
+	file := parts[1]
+	line, _ := strconv.Atoi(parts[2])
+	col, _ := strconv.Atoi(parts[3])
+	return token.Position{
+		Filename: file,
+		Line:     line,
+		Column:   col,
+	}, len(parts[0]), nil
+}
+
+type options struct {
+	Config      config.Config
+	BuildConfig BuildConfig
+
+	LintTests                bool
+	GoVersion                string
+	PrintAnalyzerMeasurement func(analysis *analysis.Analyzer, pkg *loader.PackageSpec, d time.Duration)
+}
+
+func doLint(as []*lint.Analyzer, paths []string, opt *options) (LintResult, error) {
+	if opt == nil {
+		opt = &options{}
+	}
+
+	l, err := newLinter(opt.Config)
+	if err != nil {
+		return LintResult{}, err
+	}
+	analyzers := make(map[string]*lint.Analyzer, len(as))
+	for _, a := range as {
+		analyzers[a.Analyzer.Name] = a
+	}
+	l.Analyzers = analyzers
+	l.Runner.GoVersion = opt.GoVersion
+	l.Runner.Stats.PrintAnalyzerMeasurement = opt.PrintAnalyzerMeasurement
+
+	cfg := &packages.Config{}
+	if opt.LintTests {
+		cfg.Tests = true
+	}
+
+	cfg.BuildFlags = opt.BuildConfig.Flags
+	cfg.Env = append(os.Environ(), opt.BuildConfig.Envs...)
+
+	printStats := func() {
+		// Individual stats are read atomically, but overall there
+		// is no synchronisation. For printing rough progress
+		// information, this doesn't matter.
+		switch l.Runner.Stats.State() {
+		case runner.StateInitializing:
+			fmt.Fprintln(os.Stderr, "Status: initializing")
+		case runner.StateLoadPackageGraph:
+			fmt.Fprintln(os.Stderr, "Status: loading package graph")
+		case runner.StateBuildActionGraph:
+			fmt.Fprintln(os.Stderr, "Status: building action graph")
+		case runner.StateProcessing:
+			fmt.Fprintf(os.Stderr, "Packages: %d/%d initial, %d/%d total; Workers: %d/%d\n",
+				l.Runner.Stats.ProcessedInitialPackages(),
+				l.Runner.Stats.InitialPackages(),
+				l.Runner.Stats.ProcessedPackages(),
+				l.Runner.Stats.TotalPackages(),
+				l.Runner.ActiveWorkers(),
+				l.Runner.TotalWorkers(),
+			)
+		case runner.StateFinalizing:
+			fmt.Fprintln(os.Stderr, "Status: finalizing")
+		}
+	}
+	if len(infoSignals) > 0 {
+		ch := make(chan os.Signal, 1)
+		signal.Notify(ch, infoSignals...)
+		defer signal.Stop(ch)
+		go func() {
+			for range ch {
+				printStats()
+			}
+		}()
+	}
+	res, err := l.Lint(cfg, paths)
+	for i := range res.Diagnostics {
+		res.Diagnostics[i].BuildName = opt.BuildConfig.Name
+	}
+	return res, err
+}

vendor/honnef.co/go/tools/lintcmd/runner/stats.go

@@ -0,0 +1,49 @@
+package runner
+
+import (
+	"sync/atomic"
+	"time"
+
+	"honnef.co/go/tools/go/loader"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+const (
+	StateInitializing = iota
+	StateLoadPackageGraph
+	StateBuildActionGraph
+	StateProcessing
+	StateFinalizing
+)
+
+type Stats struct {
+	state                    uint32
+	initialPackages          uint32
+	totalPackages            uint32
+	processedPackages        uint32
+	processedInitialPackages uint32
+
+	// optional function to call every time an analyzer has finished analyzing a package.
+	PrintAnalyzerMeasurement func(*analysis.Analyzer, *loader.PackageSpec, time.Duration)
+}
+
+func (s *Stats) setState(state uint32)    { atomic.StoreUint32(&s.state, state) }
+func (s *Stats) State() int               { return int(atomic.LoadUint32(&s.state)) }
+func (s *Stats) setInitialPackages(n int) { atomic.StoreUint32(&s.initialPackages, uint32(n)) }
+func (s *Stats) InitialPackages() int     { return int(atomic.LoadUint32(&s.initialPackages)) }
+func (s *Stats) setTotalPackages(n int)   { atomic.StoreUint32(&s.totalPackages, uint32(n)) }
+func (s *Stats) TotalPackages() int       { return int(atomic.LoadUint32(&s.totalPackages)) }
+
+func (s *Stats) finishPackage()         { atomic.AddUint32(&s.processedPackages, 1) }
+func (s *Stats) finishInitialPackage()  { atomic.AddUint32(&s.processedInitialPackages, 1) }
+func (s *Stats) ProcessedPackages() int { return int(atomic.LoadUint32(&s.processedPackages)) }
+func (s *Stats) ProcessedInitialPackages() int {
+	return int(atomic.LoadUint32(&s.processedInitialPackages))
+}
+
+func (s *Stats) measureAnalyzer(analysis *analysis.Analyzer, pkg *loader.PackageSpec, d time.Duration) {
+	if s.PrintAnalyzerMeasurement != nil {
+		s.PrintAnalyzerMeasurement(analysis, pkg, d)
+	}
+}

vendor/honnef.co/go/tools/lintcmd/sarif.go

@@ -0,0 +1,370 @@
+package lintcmd
+
+// Notes on GitHub-specific restrictions:
+//
+// Result.Message needs to either have ID or Text set. Markdown
+// gets ignored. Text isn't treated verbatim however: Markdown
+// formatting gets stripped, except for links.
+//
+// GitHub does not display RelatedLocations. The only way to make
+// use of them is to link to them (via their ID) in the
+// Result.Message. And even then, it will only show the referred
+// line of code, not the message. We can duplicate the messages in
+// the Result.Message, but we can't even indent them, because
+// leading whitespace gets stripped.
+//
+// GitHub does use the Markdown version of rule help, but it
+// renders it the way it renders comments on issues – that is, it
+// turns line breaks into hard line breaks, even though it
+// shouldn't.
+//
+// GitHub doesn't make use of the tool's URI or version, nor of
+// the help URIs of rules.
+//
+// There does not seem to be a way of using SARIF for "normal" CI,
+// without results showing up as code scanning alerts. Also, a
+// SARIF file containing only warnings, no errors, will not fail
+// CI by default, but this is configurable.
+// GitHub does display some parts of SARIF results in PRs, but
+// most of the useful parts of SARIF, such as help text of rules,
+// is only accessible via the code scanning alerts, which are only
+// accessible by users with write permissions.
+//
+// Result.Suppressions is being ignored.
+//
+//
+// Notes on other tools
+//
+// VS Code Sarif viewer
+//
+// The Sarif viewer in VS Code displays the full message in the
+// tabular view, removing newlines. That makes our multi-line
+// messages (which we use as a workaround for missing related
+// information) very ugly.
+//
+// Much like GitHub, the Sarif viewer does not make related
+// information visible unless we explicitly refer to it in the
+// message.
+//
+// Suggested fixes are not exposed in any way.
+//
+// It only shows the shortDescription or fullDescription of a
+// rule, not its help. We can't put the help in fullDescription,
+// because the fullDescription isn't meant to be that long. For
+// example, GitHub displays it in a single line, under the
+// shortDescription.
+//
+// VS Code can filter based on Result.Suppressions, but it doesn't
+// display our suppression message. Also, by default, suppressed
+// results get shown, and the column indicating that a result is
+// suppressed is hidden, which makes for a confusing experience.
+//
+// When a rule has only an ID, no name, VS Code displays a
+// prominent dash in place of the name. When the name and ID are
+// identical, it prints both. However, we can't make them
+// identical, as SARIF requires that either the ID and name are
+// different, or that the name is omitted.
+
+// FIXME(dh): we're currently reporting column information using UTF-8
+// byte offsets, not using Unicode code points or UTF-16, which are
+// the only two ways allowed by SARIF.
+
+// TODO(dh) set properties.tags – we can use different tags for the
+// staticcheck, simple, stylecheck and unused checks, so users can
+// filter their results
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/url"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/sarif"
+)
+
+type sarifFormatter struct {
+	driverName    string
+	driverVersion string
+	driverWebsite string
+}
+
+func sarifLevel(severity lint.Severity) string {
+	switch severity {
+	case lint.SeverityNone:
+		// no configured severity, default to warning
+		return "warning"
+	case lint.SeverityError:
+		return "error"
+	case lint.SeverityDeprecated:
+		return "warning"
+	case lint.SeverityWarning:
+		return "warning"
+	case lint.SeverityInfo:
+		return "note"
+	case lint.SeverityHint:
+		return "note"
+	default:
+		// unreachable
+		return "none"
+	}
+}
+
+func encodePath(path string) string {
+	return (&url.URL{Path: path}).EscapedPath()
+}
+
+func sarifURI(path string) string {
+	u := url.URL{
+		Scheme: "file",
+		Path:   path,
+	}
+	return u.String()
+}
+
+func sarifArtifactLocation(name string) sarif.ArtifactLocation {
+	// Ideally we use relative paths so that GitHub can resolve them
+	name = shortPath(name)
+	if filepath.IsAbs(name) {
+		return sarif.ArtifactLocation{
+			URI: sarifURI(name),
+		}
+	} else {
+		return sarif.ArtifactLocation{
+			URI:       encodePath(name),
+			URIBaseID: "%SRCROOT%", // This is specific to GitHub,
+		}
+	}
+}
+
+func sarifFormatText(s string) string {
+	// GitHub doesn't ignore line breaks, even though it should, so we remove them.
+
+	var out strings.Builder
+	lines := strings.Split(s, "\n")
+	for i, line := range lines[:len(lines)-1] {
+		out.WriteString(line)
+		if line == "" {
+			out.WriteString("\n")
+		} else {
+			nextLine := lines[i+1]
+			if nextLine == "" || strings.HasPrefix(line, "> ") || strings.HasPrefix(line, "    ") {
+				out.WriteString("\n")
+			} else {
+				out.WriteString(" ")
+			}
+		}
+	}
+	out.WriteString(lines[len(lines)-1])
+	return convertCodeBlocks(out.String())
+}
+
+func moreCodeFollows(lines []string) bool {
+	for _, line := range lines {
+		if line == "" {
+			continue
+		}
+		if strings.HasPrefix(line, "    ") {
+			return true
+		} else {
+			return false
+		}
+	}
+	return false
+}
+
+var alpha = regexp.MustCompile(`^[a-zA-Z ]+$`)
+
+func convertCodeBlocks(text string) string {
+	var buf strings.Builder
+	lines := strings.Split(text, "\n")
+
+	inCode := false
+	empties := 0
+	for i, line := range lines {
+		if inCode {
+			if !moreCodeFollows(lines[i:]) {
+				if inCode {
+					fmt.Fprintln(&buf, "```")
+					inCode = false
+				}
+			}
+		}
+
+		prevEmpties := empties
+		if line == "" && !inCode {
+			empties++
+		} else {
+			empties = 0
+		}
+
+		if line == "" {
+			fmt.Fprintln(&buf)
+			continue
+		}
+
+		if strings.HasPrefix(line, "    ") {
+			line = line[4:]
+			if !inCode {
+				fmt.Fprintln(&buf, "```go")
+				inCode = true
+			}
+		}
+
+		onlyAlpha := alpha.MatchString(line)
+		out := line
+		if !inCode && prevEmpties >= 2 && onlyAlpha {
+			fmt.Fprintf(&buf, "## %s\n", out)
+		} else {
+			fmt.Fprint(&buf, out)
+			fmt.Fprintln(&buf)
+		}
+	}
+	if inCode {
+		fmt.Fprintln(&buf, "```")
+	}
+
+	return buf.String()
+}
+
+func (o *sarifFormatter) Format(checks []*lint.Analyzer, diagnostics []diagnostic) {
+	// TODO(dh): some diagnostics shouldn't be reported as results. For example, when the user specifies a package on the command line that doesn't exist.
+
+	cwd, _ := os.Getwd()
+	run := sarif.Run{
+		Tool: sarif.Tool{
+			Driver: sarif.ToolComponent{
+				Name:           o.driverName,
+				Version:        o.driverVersion,
+				InformationURI: o.driverWebsite,
+			},
+		},
+		Invocations: []sarif.Invocation{{
+			Arguments: os.Args[1:],
+			WorkingDirectory: sarif.ArtifactLocation{
+				URI: sarifURI(cwd),
+			},
+			ExecutionSuccessful: true,
+		}},
+	}
+	for _, c := range checks {
+		run.Tool.Driver.Rules = append(run.Tool.Driver.Rules,
+			sarif.ReportingDescriptor{
+				// We don't set Name, as Name and ID mustn't be identical.
+				ID: c.Analyzer.Name,
+				ShortDescription: sarif.Message{
+					Text:     c.Doc.Title,
+					Markdown: c.Doc.TitleMarkdown,
+				},
+				HelpURI: "https://staticcheck.io/docs/checks#" + c.Analyzer.Name,
+				// We use our markdown as the plain text version, too. We
+				// use very little markdown, primarily quotations,
+				// indented code blocks and backticks. All of these are
+				// fine as plain text, too.
+				Help: sarif.Message{
+					Text:     sarifFormatText(c.Doc.Format(false)),
+					Markdown: sarifFormatText(c.Doc.FormatMarkdown(false)),
+				},
+				DefaultConfiguration: sarif.ReportingConfiguration{
+					// TODO(dh): we could figure out which checks were disabled globally
+					Enabled: true,
+					Level:   sarifLevel(c.Doc.Severity),
+				},
+			})
+	}
+
+	for _, p := range diagnostics {
+		r := sarif.Result{
+			RuleID: p.Category,
+			Kind:   sarif.Fail,
+			Message: sarif.Message{
+				Text: p.Message,
+			},
+		}
+		r.Locations = []sarif.Location{{
+			PhysicalLocation: sarif.PhysicalLocation{
+				ArtifactLocation: sarifArtifactLocation(p.Position.Filename),
+				Region: sarif.Region{
+					StartLine:   p.Position.Line,
+					StartColumn: p.Position.Column,
+					EndLine:     p.End.Line,
+					EndColumn:   p.End.Column,
+				},
+			},
+		}}
+		for _, fix := range p.SuggestedFixes {
+			sfix := sarif.Fix{
+				Description: sarif.Message{
+					Text: fix.Message,
+				},
+			}
+			// file name -> replacements
+			changes := map[string][]sarif.Replacement{}
+			for _, edit := range fix.TextEdits {
+				changes[edit.Position.Filename] = append(changes[edit.Position.Filename], sarif.Replacement{
+					DeletedRegion: sarif.Region{
+						StartLine:   edit.Position.Line,
+						StartColumn: edit.Position.Column,
+						EndLine:     edit.End.Line,
+						EndColumn:   edit.End.Column,
+					},
+					InsertedContent: sarif.ArtifactContent{
+						Text: string(edit.NewText),
+					},
+				})
+			}
+			for path, replacements := range changes {
+				sfix.ArtifactChanges = append(sfix.ArtifactChanges, sarif.ArtifactChange{
+					ArtifactLocation: sarifArtifactLocation(path),
+					Replacements:     replacements,
+				})
+			}
+			r.Fixes = append(r.Fixes, sfix)
+		}
+		for i, related := range p.Related {
+			r.Message.Text += fmt.Sprintf("\n\t[%s](%d)", related.Message, i+1)
+
+			r.RelatedLocations = append(r.RelatedLocations,
+				sarif.Location{
+					ID: i + 1,
+					Message: &sarif.Message{
+						Text: related.Message,
+					},
+					PhysicalLocation: sarif.PhysicalLocation{
+						ArtifactLocation: sarifArtifactLocation(related.Position.Filename),
+						Region: sarif.Region{
+							StartLine:   related.Position.Line,
+							StartColumn: related.Position.Column,
+							EndLine:     related.End.Line,
+							EndColumn:   related.End.Column,
+						},
+					},
+				})
+		}
+
+		if p.Severity == severityIgnored {
+			// Note that GitHub does not support suppressions, which is why Staticcheck still requires the -show-ignored flag to be set for us to emit ignored diagnostics.
+
+			r.Suppressions = []sarif.Suppression{{
+				Kind: "inSource",
+				// TODO(dh): populate the Justification field
+			}}
+		} else {
+			// We want an empty slice, not nil. SARIF differentiates
+			// between the two. An empty slice means that the diagnostic
+			// wasn't suppressed, while nil means that we don't have the
+			// information available.
+			r.Suppressions = []sarif.Suppression{}
+		}
+		run.Results = append(run.Results, r)
+	}
+
+	json.NewEncoder(os.Stdout).Encode(sarif.Log{
+		Version: sarif.Version,
+		Schema:  sarif.Schema,
+		Runs:    []sarif.Run{run},
+	})
+}

vendor/honnef.co/go/tools/lintcmd/stats.go

@@ -0,0 +1,8 @@
+//go:build !aix && !android && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !solaris
+// +build !aix,!android,!darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd,!solaris
+
+package lintcmd
+
+import "os"
+
+var infoSignals = []os.Signal{}

vendor/honnef.co/go/tools/lintcmd/stats_bsd.go

@@ -0,0 +1,11 @@
+//go:build darwin || dragonfly || freebsd || netbsd || openbsd
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package lintcmd
+
+import (
+	"os"
+	"syscall"
+)
+
+var infoSignals = []os.Signal{syscall.SIGINFO}

vendor/honnef.co/go/tools/lintcmd/stats_posix.go

@@ -0,0 +1,11 @@
+//go:build aix || android || linux || solaris
+// +build aix android linux solaris
+
+package lintcmd
+
+import (
+	"os"
+	"syscall"
+)
+
+var infoSignals = []os.Signal{syscall.SIGUSR1}

vendor/honnef.co/go/tools/lintcmd/version/buildinfo.go

@@ -0,0 +1,44 @@
+package version
+
+import (
+	"fmt"
+	"runtime/debug"
+)
+
+func printBuildInfo() {
+	if info, ok := debug.ReadBuildInfo(); ok {
+		fmt.Println("Main module:")
+		printModule(&info.Main)
+		fmt.Println("Dependencies:")
+		for _, dep := range info.Deps {
+			printModule(dep)
+		}
+	} else {
+		fmt.Println("Built without Go modules")
+	}
+}
+
+func buildInfoVersion() (string, bool) {
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "", false
+	}
+	if info.Main.Version == "(devel)" {
+		return "", false
+	}
+	return info.Main.Version, true
+}
+
+func printModule(m *debug.Module) {
+	fmt.Printf("\t%s", m.Path)
+	if m.Version != "(devel)" {
+		fmt.Printf("@%s", m.Version)
+	}
+	if m.Sum != "" {
+		fmt.Printf(" (sum: %s)", m.Sum)
+	}
+	if m.Replace != nil {
+		fmt.Printf(" (replace: %s)", m.Replace.Path)
+	}
+	fmt.Println()
+}

vendor/honnef.co/go/tools/lintcmd/version/version.go

@@ -0,0 +1,43 @@
+package version
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+)
+
+const Version = "2022.1.1"
+const MachineVersion = "v0.3.1"
+
+// version returns a version descriptor and reports whether the
+// version is a known release.
+func version(human, machine string) (human_, machine_ string, known bool) {
+	if human != "devel" {
+		return human, machine, true
+	}
+	v, ok := buildInfoVersion()
+	if ok {
+		return v, "", false
+	}
+	return "devel", "", false
+}
+
+func Print(human, machine string) {
+	human, machine, release := version(human, machine)
+
+	if release {
+		fmt.Printf("%s %s (%s)\n", filepath.Base(os.Args[0]), human, machine)
+	} else if human == "devel" {
+		fmt.Printf("%s (no version)\n", filepath.Base(os.Args[0]))
+	} else {
+		fmt.Printf("%s (devel, %s)\n", filepath.Base(os.Args[0]), human)
+	}
+}
+
+func Verbose(human, machine string) {
+	Print(human, machine)
+	fmt.Println()
+	fmt.Println("Compiled with Go version:", runtime.Version())
+	printBuildInfo()
+}

vendor/honnef.co/go/tools/pattern/convert.go

@@ -0,0 +1,245 @@
+package pattern
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"reflect"
+
+	"golang.org/x/exp/typeparams"
+)
+
+var astTypes = map[string]reflect.Type{
+	"Ellipsis":       reflect.TypeOf(ast.Ellipsis{}),
+	"RangeStmt":      reflect.TypeOf(ast.RangeStmt{}),
+	"AssignStmt":     reflect.TypeOf(ast.AssignStmt{}),
+	"IndexExpr":      reflect.TypeOf(ast.IndexExpr{}),
+	"IndexListExpr":  reflect.TypeOf(typeparams.IndexListExpr{}),
+	"Ident":          reflect.TypeOf(ast.Ident{}),
+	"ValueSpec":      reflect.TypeOf(ast.ValueSpec{}),
+	"GenDecl":        reflect.TypeOf(ast.GenDecl{}),
+	"BinaryExpr":     reflect.TypeOf(ast.BinaryExpr{}),
+	"ForStmt":        reflect.TypeOf(ast.ForStmt{}),
+	"ArrayType":      reflect.TypeOf(ast.ArrayType{}),
+	"DeferStmt":      reflect.TypeOf(ast.DeferStmt{}),
+	"MapType":        reflect.TypeOf(ast.MapType{}),
+	"ReturnStmt":     reflect.TypeOf(ast.ReturnStmt{}),
+	"SliceExpr":      reflect.TypeOf(ast.SliceExpr{}),
+	"StarExpr":       reflect.TypeOf(ast.StarExpr{}),
+	"UnaryExpr":      reflect.TypeOf(ast.UnaryExpr{}),
+	"SendStmt":       reflect.TypeOf(ast.SendStmt{}),
+	"SelectStmt":     reflect.TypeOf(ast.SelectStmt{}),
+	"ImportSpec":     reflect.TypeOf(ast.ImportSpec{}),
+	"IfStmt":         reflect.TypeOf(ast.IfStmt{}),
+	"GoStmt":         reflect.TypeOf(ast.GoStmt{}),
+	"Field":          reflect.TypeOf(ast.Field{}),
+	"SelectorExpr":   reflect.TypeOf(ast.SelectorExpr{}),
+	"StructType":     reflect.TypeOf(ast.StructType{}),
+	"KeyValueExpr":   reflect.TypeOf(ast.KeyValueExpr{}),
+	"FuncType":       reflect.TypeOf(ast.FuncType{}),
+	"FuncLit":        reflect.TypeOf(ast.FuncLit{}),
+	"FuncDecl":       reflect.TypeOf(ast.FuncDecl{}),
+	"ChanType":       reflect.TypeOf(ast.ChanType{}),
+	"CallExpr":       reflect.TypeOf(ast.CallExpr{}),
+	"CaseClause":     reflect.TypeOf(ast.CaseClause{}),
+	"CommClause":     reflect.TypeOf(ast.CommClause{}),
+	"CompositeLit":   reflect.TypeOf(ast.CompositeLit{}),
+	"EmptyStmt":      reflect.TypeOf(ast.EmptyStmt{}),
+	"SwitchStmt":     reflect.TypeOf(ast.SwitchStmt{}),
+	"TypeSwitchStmt": reflect.TypeOf(ast.TypeSwitchStmt{}),
+	"TypeAssertExpr": reflect.TypeOf(ast.TypeAssertExpr{}),
+	"TypeSpec":       reflect.TypeOf(ast.TypeSpec{}),
+	"InterfaceType":  reflect.TypeOf(ast.InterfaceType{}),
+	"BranchStmt":     reflect.TypeOf(ast.BranchStmt{}),
+	"IncDecStmt":     reflect.TypeOf(ast.IncDecStmt{}),
+	"BasicLit":       reflect.TypeOf(ast.BasicLit{}),
+}
+
+func ASTToNode(node interface{}) Node {
+	switch node := node.(type) {
+	case *ast.File:
+		panic("cannot convert *ast.File to Node")
+	case nil:
+		return Nil{}
+	case string:
+		return String(node)
+	case token.Token:
+		return Token(node)
+	case *ast.ExprStmt:
+		return ASTToNode(node.X)
+	case *ast.BlockStmt:
+		if node == nil {
+			return Nil{}
+		}
+		return ASTToNode(node.List)
+	case *ast.FieldList:
+		if node == nil {
+			return Nil{}
+		}
+		return ASTToNode(node.List)
+	case *ast.BasicLit:
+		if node == nil {
+			return Nil{}
+		}
+	case *ast.ParenExpr:
+		return ASTToNode(node.X)
+	}
+
+	if node, ok := node.(ast.Node); ok {
+		name := reflect.TypeOf(node).Elem().Name()
+		T, ok := structNodes[name]
+		if !ok {
+			panic(fmt.Sprintf("internal error: unhandled type %T", node))
+		}
+
+		if reflect.ValueOf(node).IsNil() {
+			return Nil{}
+		}
+		v := reflect.ValueOf(node).Elem()
+		objs := make([]Node, T.NumField())
+		for i := 0; i < T.NumField(); i++ {
+			f := v.FieldByName(T.Field(i).Name)
+			objs[i] = ASTToNode(f.Interface())
+		}
+
+		n, err := populateNode(name, objs, false)
+		if err != nil {
+			panic(fmt.Sprintf("internal error: %s", err))
+		}
+		return n
+	}
+
+	s := reflect.ValueOf(node)
+	if s.Kind() == reflect.Slice {
+		if s.Len() == 0 {
+			return List{}
+		}
+		if s.Len() == 1 {
+			return ASTToNode(s.Index(0).Interface())
+		}
+
+		tail := List{}
+		for i := s.Len() - 1; i >= 0; i-- {
+			head := ASTToNode(s.Index(i).Interface())
+			l := List{
+				Head: head,
+				Tail: tail,
+			}
+			tail = l
+		}
+		return tail
+	}
+
+	panic(fmt.Sprintf("internal error: unhandled type %T", node))
+}
+
+func NodeToAST(node Node, state State) interface{} {
+	switch node := node.(type) {
+	case Binding:
+		v, ok := state[node.Name]
+		if !ok {
+			// really we want to return an error here
+			panic("XXX")
+		}
+		switch v := v.(type) {
+		case types.Object:
+			return &ast.Ident{Name: v.Name()}
+		default:
+			return v
+		}
+	case Builtin, Any, Object, Function, Not, Or:
+		panic("XXX")
+	case List:
+		if (node == List{}) {
+			return []ast.Node{}
+		}
+		x := []ast.Node{NodeToAST(node.Head, state).(ast.Node)}
+		x = append(x, NodeToAST(node.Tail, state).([]ast.Node)...)
+		return x
+	case Token:
+		return token.Token(node)
+	case String:
+		return string(node)
+	case Nil:
+		return nil
+	}
+
+	name := reflect.TypeOf(node).Name()
+	T, ok := astTypes[name]
+	if !ok {
+		panic(fmt.Sprintf("internal error: unhandled type %T", node))
+	}
+	v := reflect.ValueOf(node)
+	out := reflect.New(T)
+	for i := 0; i < T.NumField(); i++ {
+		fNode := v.FieldByName(T.Field(i).Name)
+		if (fNode == reflect.Value{}) {
+			continue
+		}
+		fAST := out.Elem().FieldByName(T.Field(i).Name)
+		switch fAST.Type().Kind() {
+		case reflect.Slice:
+			c := reflect.ValueOf(NodeToAST(fNode.Interface().(Node), state))
+			if c.Kind() != reflect.Slice {
+				// it's a single node in the pattern, we have to wrap
+				// it in a slice
+				slice := reflect.MakeSlice(fAST.Type(), 1, 1)
+				slice.Index(0).Set(c)
+				c = slice
+			}
+			switch fAST.Interface().(type) {
+			case []ast.Node:
+				switch cc := c.Interface().(type) {
+				case []ast.Node:
+					fAST.Set(c)
+				case []ast.Expr:
+					var slice []ast.Node
+					for _, el := range cc {
+						slice = append(slice, el)
+					}
+					fAST.Set(reflect.ValueOf(slice))
+				default:
+					panic("XXX")
+				}
+			case []ast.Expr:
+				switch cc := c.Interface().(type) {
+				case []ast.Node:
+					var slice []ast.Expr
+					for _, el := range cc {
+						slice = append(slice, el.(ast.Expr))
+					}
+					fAST.Set(reflect.ValueOf(slice))
+				case []ast.Expr:
+					fAST.Set(c)
+				default:
+					panic("XXX")
+				}
+			default:
+				panic("XXX")
+			}
+		case reflect.Int:
+			c := reflect.ValueOf(NodeToAST(fNode.Interface().(Node), state))
+			switch c.Kind() {
+			case reflect.String:
+				tok, ok := tokensByString[c.Interface().(string)]
+				if !ok {
+					// really we want to return an error here
+					panic("XXX")
+				}
+				fAST.SetInt(int64(tok))
+			case reflect.Int:
+				fAST.Set(c)
+			default:
+				panic(fmt.Sprintf("internal error: unexpected kind %s", c.Kind()))
+			}
+		default:
+			r := NodeToAST(fNode.Interface().(Node), state)
+			if r != nil {
+				fAST.Set(reflect.ValueOf(r))
+			}
+		}
+	}
+
+	return out.Interface().(ast.Node)
+}

vendor/honnef.co/go/tools/pattern/doc.go

@@ -0,0 +1,273 @@
+/*
+Package pattern implements a simple language for pattern matching Go ASTs.
+
+Design decisions and trade-offs
+
+The language is designed specifically for the task of filtering ASTs
+to simplify the implementation of analyses in staticcheck.
+It is also intended to be trivial to parse and execute.
+
+To that end, we make certain decisions that make the language more
+suited to its task, while making certain queries infeasible.
+
+Furthermore, it is fully expected that the majority of analyses will still require ordinary Go code
+to further process the filtered AST, to make use of type information and to enforce complex invariants.
+It is not our goal to design a scripting language for writing entire checks in.
+
+The language
+
+At its core, patterns are a representation of Go ASTs, allowing for the use of placeholders to enable pattern matching.
+Their syntax is inspired by LISP and Haskell, but unlike LISP, the core unit of patterns isn't the list, but the node.
+There is a fixed set of nodes, identified by name, and with the exception of the Or node, all nodes have a fixed number of arguments.
+In addition to nodes, there are atoms, which represent basic units such as strings or the nil value.
+
+Pattern matching is implemented via bindings, represented by the Binding node.
+A Binding can match nodes and associate them with names, to later recall the nodes.
+This allows for expressing "this node must be equal to that node" constraints.
+
+To simplify writing and reading patterns, a small amount of additional syntax exists on top of nodes and atoms.
+This additional syntax doesn't add any new features of its own, it simply provides shortcuts to creating nodes and atoms.
+
+To show an example of a pattern, first consider this snippet of Go code:
+
+	if x := fn(); x != nil {
+		for _, v := range x {
+			println(v, x)
+		}
+	}
+
+The corresponding AST expressed as an idiomatic pattern would look as follows:
+
+	(IfStmt
+		(AssignStmt (Ident "x") ":=" (CallExpr (Ident "fn") []))
+		(BinaryExpr (Ident "x") "!=" (Ident "nil"))
+		(RangeStmt
+			(Ident "_") (Ident "v") ":=" (Ident "x")
+			(CallExpr (Ident "println") [(Ident "v") (Ident "x")]))
+		nil)
+
+Two things are worth noting about this representation.
+First, the [el1 el2 ...] syntax is a short-hand for creating lists.
+It is a short-hand for el1:el2:[], which itself is a short-hand for (List el1 (List el2 (List nil nil)).
+Second, note the absence of a lot of lists in places that normally accept lists.
+For example, assignment assigns a number of right-hands to a number of left-hands, yet our AssignStmt is lacking any form of list.
+This is due to the fact that a single node can match a list of exactly one element.
+Thus, the two following forms have identical matching behavior:
+
+	(AssignStmt (Ident "x") ":=" (CallExpr (Ident "fn") []))
+	(AssignStmt [(Ident "x")] ":=" [(CallExpr (Ident "fn") [])])
+
+This section serves as an overview of the language's syntax.
+More in-depth explanations of the matching behavior as well as an exhaustive list of node types follows in the coming sections.
+
+Pattern matching
+
+TODO write about pattern matching
+
+- inspired by haskell syntax, but much, much simpler and naive
+
+Node types
+
+The language contains two kinds of nodes: those that map to nodes in the AST, and those that implement additional logic.
+
+Nodes that map directly to AST nodes are named identically to the types in the go/ast package.
+What follows is an exhaustive list of these nodes:
+
+	(ArrayType len elt)
+	(AssignStmt lhs tok rhs)
+	(BasicLit kind value)
+	(BinaryExpr x op y)
+	(BranchStmt tok label)
+	(CallExpr fun args)
+	(CaseClause list body)
+	(ChanType dir value)
+	(CommClause comm body)
+	(CompositeLit type elts)
+	(DeferStmt call)
+	(Ellipsis elt)
+	(EmptyStmt)
+	(Field names type tag)
+	(ForStmt init cond post body)
+	(FuncDecl recv name type body)
+	(FuncLit type body)
+	(FuncType params results)
+	(GenDecl specs)
+	(GoStmt call)
+	(Ident name)
+	(IfStmt init cond body else)
+	(ImportSpec name path)
+	(IncDecStmt x tok)
+	(IndexExpr x index)
+	(InterfaceType methods)
+	(KeyValueExpr key value)
+	(MapType key value)
+	(RangeStmt key value tok x body)
+	(ReturnStmt results)
+	(SelectStmt body)
+	(SelectorExpr x sel)
+	(SendStmt chan value)
+	(SliceExpr x low high max)
+	(StarExpr x)
+	(StructType fields)
+	(SwitchStmt init tag body)
+	(TypeAssertExpr)
+	(TypeSpec name type)
+	(TypeSwitchStmt init assign body)
+	(UnaryExpr op x)
+	(ValueSpec names type values)
+
+Additionally, there are the String, Token and nil atoms.
+Strings are double-quoted string literals, as in (Ident "someName").
+Tokens are also represented as double-quoted string literals, but are converted to token.Token values in contexts that require tokens,
+such as in (BinaryExpr x "<" y), where "<" is transparently converted to token.LSS during matching.
+The keyword 'nil' denotes the nil value, which represents the absence of any value.
+
+We also define the (List head tail) node, which is used to represent sequences of elements as a singly linked list.
+The head is a single element, and the tail is the remainder of the list.
+For example,
+
+	(List "foo" (List "bar" (List "baz" (List nil nil))))
+
+represents a list of three elements, "foo", "bar" and "baz". There is dedicated syntax for writing lists, which looks as follows:
+
+	["foo" "bar" "baz"]
+
+This syntax is itself syntactic sugar for the following form:
+
+	"foo":"bar":"baz":[]
+
+This form is of particular interest for pattern matching, as it allows matching on the head and tail. For example,
+
+	"foo":"bar":_
+
+would match any list with at least two elements, where the first two elements are "foo" and "bar". This is equivalent to writing
+
+	(List "foo" (List "bar" _))
+
+Note that it is not possible to match from the end of the list.
+That is, there is no way to express a query such as "a list of any length where the last element is foo".
+
+Note that unlike in LISP, nil and empty lists are distinct from one another.
+In patterns, with respect to lists, nil is akin to Go's untyped nil.
+It will match a nil ast.Node, but it will not match a nil []ast.Expr. Nil will, however, match pointers to named types such as *ast.Ident.
+Similarly, lists are akin to Go's
+slices. An empty list will match both a nil and an empty []ast.Expr, but it will not match a nil ast.Node.
+
+Due to the difference between nil and empty lists, an empty list is represented as (List nil nil), i.e. a list with no head or tail.
+Similarly, a list of one element is represented as (List el (List nil nil)). Unlike in LISP, it cannot be represented by (List el nil).
+
+Finally, there are nodes that implement special logic or matching behavior.
+
+(Any) matches any value. The underscore (_) maps to this node, making the following two forms equivalent:
+
+	(Ident _)
+	(Ident (Any))
+
+(Builtin name) matches a built-in identifier or function by name.
+This is a type-aware variant of (Ident name).
+Instead of only comparing the name, it resolves the object behind the name and makes sure it's a pre-declared identifier.
+
+For example, in the following piece of code
+
+	func fn() {
+		println(true)
+		true := false
+		println(true)
+	}
+
+the pattern
+
+	(Builtin "true")
+
+will match exactly once, on the first use of 'true' in the function.
+Subsequent occurrences of 'true' no longer refer to the pre-declared identifier.
+
+(Object name) matches an identifier by name, but yields the
+types.Object it refers to.
+
+(Function name) matches ast.Idents and ast.SelectorExprs that refer to a function with a given fully qualified name.
+For example, "net/url.PathEscape" matches the PathEscape function in the net/url package,
+and "(net/url.EscapeError).Error" refers to the Error method on the net/url.EscapeError type,
+either on an instance of the type, or on the type itself.
+
+For example, the following patterns match the following lines of code:
+
+	(CallExpr (Function "fmt.Println") _) // pattern 1
+	(CallExpr (Function "(net/url.EscapeError).Error") _) // pattern 2
+
+	fmt.Println("hello, world") // matches pattern 1
+	var x url.EscapeError
+	x.Error() // matches pattern 2
+	(url.EscapeError).Error(x) // also matches pattern 2
+
+(Binding name node) creates or uses a binding.
+Bindings work like variable assignments, allowing referring to already matched nodes.
+As an example, bindings are necessary to match self-assignment of the form "x = x",
+since we need to express that the right-hand side is identical to the left-hand side.
+
+If a binding's node is not nil, the matcher will attempt to match a node according to the pattern.
+If a binding's node is nil, the binding will either recall an existing value, or match the Any node.
+It is an error to provide a non-nil node to a binding that has already been bound.
+
+Referring back to the earlier example, the following pattern will match self-assignment of idents:
+
+	(AssignStmt (Binding "lhs" (Ident _)) "=" (Binding "lhs" nil))
+
+Because bindings are a crucial component of pattern matching, there is special syntax for creating and recalling bindings.
+Lower-case names refer to bindings. If standing on its own, the name "foo" will be equivalent to (Binding "foo" nil).
+If a name is followed by an at-sign (@) then it will create a binding for the node that follows.
+Together, this allows us to rewrite the earlier example as follows:
+
+	(AssignStmt lhs@(Ident _) "=" lhs)
+
+(Or nodes...) is a variadic node that tries matching each node until one succeeds. For example, the following pattern matches all idents of name "foo" or "bar":
+
+	(Ident (Or "foo" "bar"))
+
+We could also have written
+
+	(Or (Ident "foo") (Ident "bar"))
+
+and achieved the same result. We can also mix different kinds of nodes:
+
+	(Or (Ident "foo") (CallExpr (Ident "bar") _))
+
+When using bindings inside of nodes used inside Or, all or none of the bindings will be bound.
+That is, partially matched nodes that ultimately failed to match will not produce any bindings observable outside of the matching attempt.
+We can thus write
+
+	(Or (Ident name) (CallExpr name))
+
+and 'name' will either be a String if the first option matched, or an Ident or SelectorExpr if the second option matched.
+
+(Not node)
+
+The Not node negates a match. For example, (Not (Ident _)) will match all nodes that aren't identifiers.
+
+ChanDir(0)
+
+Automatic unnesting of AST nodes
+
+The Go AST has several types of nodes that wrap other nodes.
+To simplify matching, we automatically unwrap some of these nodes.
+
+These nodes are ExprStmt (for using expressions in a statement context),
+ParenExpr (for parenthesized expressions),
+DeclStmt (for declarations in a statement context),
+and LabeledStmt (for labeled statements).
+
+Thus, the query
+
+	(FuncLit _ [(CallExpr _ _)]
+
+will match a function literal containing a single function call,
+even though in the actual Go AST, the CallExpr is nested inside an ExprStmt,
+as function bodies are made up of sequences of statements.
+
+On the flip-side, there is no way to specifically match these wrapper nodes.
+For example, there is no way of searching for unnecessary parentheses, like in the following piece of Go code:
+
+	((x)) += 2
+
+*/
+package pattern

vendor/honnef.co/go/tools/pattern/fuzz.go

@@ -0,0 +1,51 @@
+//go:build gofuzz
+// +build gofuzz
+
+package pattern
+
+import (
+	"go/ast"
+	goparser "go/parser"
+	"go/token"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var files []*ast.File
+
+func init() {
+	fset := token.NewFileSet()
+	filepath.Walk("/usr/lib/go/src", func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			// XXX error handling
+			panic(err)
+		}
+		if !strings.HasSuffix(path, ".go") {
+			return nil
+		}
+		f, err := goparser.ParseFile(fset, path, nil, 0)
+		if err != nil {
+			return nil
+		}
+		files = append(files, f)
+		return nil
+	})
+}
+
+func Fuzz(data []byte) int {
+	p := &Parser{}
+	pat, err := p.Parse(string(data))
+	if err != nil {
+		if strings.Contains(err.Error(), "internal error") {
+			panic(err)
+		}
+		return 0
+	}
+	_ = pat.Root.String()
+
+	for _, f := range files {
+		Match(pat.Root, f)
+	}
+	return 1
+}

vendor/honnef.co/go/tools/pattern/lexer.go

@@ -0,0 +1,221 @@
+package pattern
+
+import (
+	"fmt"
+	"go/token"
+	"unicode"
+	"unicode/utf8"
+)
+
+type lexer struct {
+	f *token.File
+
+	input string
+	start int
+	pos   int
+	width int
+	items chan item
+}
+
+type itemType int
+
+const eof = -1
+
+const (
+	itemError itemType = iota
+	itemLeftParen
+	itemRightParen
+	itemLeftBracket
+	itemRightBracket
+	itemTypeName
+	itemVariable
+	itemAt
+	itemColon
+	itemBlank
+	itemString
+	itemEOF
+)
+
+func (typ itemType) String() string {
+	switch typ {
+	case itemError:
+		return "ERROR"
+	case itemLeftParen:
+		return "("
+	case itemRightParen:
+		return ")"
+	case itemLeftBracket:
+		return "["
+	case itemRightBracket:
+		return "]"
+	case itemTypeName:
+		return "TYPE"
+	case itemVariable:
+		return "VAR"
+	case itemAt:
+		return "@"
+	case itemColon:
+		return ":"
+	case itemBlank:
+		return "_"
+	case itemString:
+		return "STRING"
+	case itemEOF:
+		return "EOF"
+	default:
+		return fmt.Sprintf("itemType(%d)", typ)
+	}
+}
+
+type item struct {
+	typ itemType
+	val string
+	pos int
+}
+
+type stateFn func(*lexer) stateFn
+
+func (l *lexer) run() {
+	for state := lexStart; state != nil; {
+		state = state(l)
+	}
+	close(l.items)
+}
+
+func (l *lexer) emitValue(t itemType, value string) {
+	l.items <- item{t, value, l.start}
+	l.start = l.pos
+}
+
+func (l *lexer) emit(t itemType) {
+	l.items <- item{t, l.input[l.start:l.pos], l.start}
+	l.start = l.pos
+}
+
+func lexStart(l *lexer) stateFn {
+	switch r := l.next(); {
+	case r == eof:
+		l.emit(itemEOF)
+		return nil
+	case unicode.IsSpace(r):
+		l.ignore()
+	case r == '(':
+		l.emit(itemLeftParen)
+	case r == ')':
+		l.emit(itemRightParen)
+	case r == '[':
+		l.emit(itemLeftBracket)
+	case r == ']':
+		l.emit(itemRightBracket)
+	case r == '@':
+		l.emit(itemAt)
+	case r == ':':
+		l.emit(itemColon)
+	case r == '_':
+		l.emit(itemBlank)
+	case r == '"':
+		l.backup()
+		return lexString
+	case unicode.IsUpper(r):
+		l.backup()
+		return lexType
+	case unicode.IsLower(r):
+		l.backup()
+		return lexVariable
+	default:
+		return l.errorf("unexpected character %c", r)
+	}
+	return lexStart
+}
+
+func (l *lexer) next() (r rune) {
+	if l.pos >= len(l.input) {
+		l.width = 0
+		return eof
+	}
+	r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
+
+	if r == '\n' {
+		l.f.AddLine(l.pos)
+	}
+
+	l.pos += l.width
+
+	return r
+}
+
+func (l *lexer) ignore() {
+	l.start = l.pos
+}
+
+func (l *lexer) backup() {
+	l.pos -= l.width
+}
+
+func (l *lexer) errorf(format string, args ...interface{}) stateFn {
+	// TODO(dh): emit position information in errors
+	l.items <- item{
+		itemError,
+		fmt.Sprintf(format, args...),
+		l.start,
+	}
+	return nil
+}
+
+func isAlphaNumeric(r rune) bool {
+	return r >= '0' && r <= '9' ||
+		r >= 'a' && r <= 'z' ||
+		r >= 'A' && r <= 'Z'
+}
+
+func lexString(l *lexer) stateFn {
+	l.next() // skip quote
+	escape := false
+
+	var runes []rune
+	for {
+		switch r := l.next(); r {
+		case eof:
+			return l.errorf("unterminated string")
+		case '"':
+			if !escape {
+				l.emitValue(itemString, string(runes))
+				return lexStart
+			} else {
+				runes = append(runes, '"')
+				escape = false
+			}
+		case '\\':
+			if escape {
+				runes = append(runes, '\\')
+				escape = false
+			} else {
+				escape = true
+			}
+		default:
+			runes = append(runes, r)
+		}
+	}
+}
+
+func lexType(l *lexer) stateFn {
+	l.next()
+	for {
+		if !isAlphaNumeric(l.next()) {
+			l.backup()
+			l.emit(itemTypeName)
+			return lexStart
+		}
+	}
+}
+
+func lexVariable(l *lexer) stateFn {
+	l.next()
+	for {
+		if !isAlphaNumeric(l.next()) {
+			l.backup()
+			l.emit(itemVariable)
+			return lexStart
+		}
+	}
+}

vendor/honnef.co/go/tools/pattern/match.go

@@ -0,0 +1,620 @@
+package pattern
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"reflect"
+
+	"golang.org/x/exp/typeparams"
+)
+
+var tokensByString = map[string]Token{
+	"INT":         Token(token.INT),
+	"FLOAT":       Token(token.FLOAT),
+	"IMAG":        Token(token.IMAG),
+	"CHAR":        Token(token.CHAR),
+	"STRING":      Token(token.STRING),
+	"+":           Token(token.ADD),
+	"-":           Token(token.SUB),
+	"*":           Token(token.MUL),
+	"/":           Token(token.QUO),
+	"%":           Token(token.REM),
+	"&":           Token(token.AND),
+	"|":           Token(token.OR),
+	"^":           Token(token.XOR),
+	"<<":          Token(token.SHL),
+	">>":          Token(token.SHR),
+	"&^":          Token(token.AND_NOT),
+	"+=":          Token(token.ADD_ASSIGN),
+	"-=":          Token(token.SUB_ASSIGN),
+	"*=":          Token(token.MUL_ASSIGN),
+	"/=":          Token(token.QUO_ASSIGN),
+	"%=":          Token(token.REM_ASSIGN),
+	"&=":          Token(token.AND_ASSIGN),
+	"|=":          Token(token.OR_ASSIGN),
+	"^=":          Token(token.XOR_ASSIGN),
+	"<<=":         Token(token.SHL_ASSIGN),
+	">>=":         Token(token.SHR_ASSIGN),
+	"&^=":         Token(token.AND_NOT_ASSIGN),
+	"&&":          Token(token.LAND),
+	"||":          Token(token.LOR),
+	"<-":          Token(token.ARROW),
+	"++":          Token(token.INC),
+	"--":          Token(token.DEC),
+	"==":          Token(token.EQL),
+	"<":           Token(token.LSS),
+	">":           Token(token.GTR),
+	"=":           Token(token.ASSIGN),
+	"!":           Token(token.NOT),
+	"!=":          Token(token.NEQ),
+	"<=":          Token(token.LEQ),
+	">=":          Token(token.GEQ),
+	":=":          Token(token.DEFINE),
+	"...":         Token(token.ELLIPSIS),
+	"IMPORT":      Token(token.IMPORT),
+	"VAR":         Token(token.VAR),
+	"TYPE":        Token(token.TYPE),
+	"CONST":       Token(token.CONST),
+	"BREAK":       Token(token.BREAK),
+	"CONTINUE":    Token(token.CONTINUE),
+	"GOTO":        Token(token.GOTO),
+	"FALLTHROUGH": Token(token.FALLTHROUGH),
+}
+
+func maybeToken(node Node) (Node, bool) {
+	if node, ok := node.(String); ok {
+		if tok, ok := tokensByString[string(node)]; ok {
+			return tok, true
+		}
+		return node, false
+	}
+	return node, false
+}
+
+func isNil(v interface{}) bool {
+	if v == nil {
+		return true
+	}
+	if _, ok := v.(Nil); ok {
+		return true
+	}
+	return false
+}
+
+type matcher interface {
+	Match(*Matcher, interface{}) (interface{}, bool)
+}
+
+type State = map[string]interface{}
+
+type Matcher struct {
+	TypesInfo *types.Info
+	State     State
+}
+
+func (m *Matcher) fork() *Matcher {
+	state := make(State, len(m.State))
+	for k, v := range m.State {
+		state[k] = v
+	}
+	return &Matcher{
+		TypesInfo: m.TypesInfo,
+		State:     state,
+	}
+}
+
+func (m *Matcher) merge(mc *Matcher) {
+	m.State = mc.State
+}
+
+func (m *Matcher) Match(a Node, b ast.Node) bool {
+	m.State = State{}
+	_, ok := match(m, a, b)
+	return ok
+}
+
+func Match(a Node, b ast.Node) (*Matcher, bool) {
+	m := &Matcher{}
+	ret := m.Match(a, b)
+	return m, ret
+}
+
+// Match two items, which may be (Node, AST) or (AST, AST)
+func match(m *Matcher, l, r interface{}) (interface{}, bool) {
+	if _, ok := r.(Node); ok {
+		panic("Node mustn't be on right side of match")
+	}
+
+	switch l := l.(type) {
+	case *ast.ParenExpr:
+		return match(m, l.X, r)
+	case *ast.ExprStmt:
+		return match(m, l.X, r)
+	case *ast.DeclStmt:
+		return match(m, l.Decl, r)
+	case *ast.LabeledStmt:
+		return match(m, l.Stmt, r)
+	case *ast.BlockStmt:
+		return match(m, l.List, r)
+	case *ast.FieldList:
+		return match(m, l.List, r)
+	}
+
+	switch r := r.(type) {
+	case *ast.ParenExpr:
+		return match(m, l, r.X)
+	case *ast.ExprStmt:
+		return match(m, l, r.X)
+	case *ast.DeclStmt:
+		return match(m, l, r.Decl)
+	case *ast.LabeledStmt:
+		return match(m, l, r.Stmt)
+	case *ast.BlockStmt:
+		if r == nil {
+			return match(m, l, nil)
+		}
+		return match(m, l, r.List)
+	case *ast.FieldList:
+		if r == nil {
+			return match(m, l, nil)
+		}
+		return match(m, l, r.List)
+	case *ast.BasicLit:
+		if r == nil {
+			return match(m, l, nil)
+		}
+	}
+
+	if l, ok := l.(matcher); ok {
+		return l.Match(m, r)
+	}
+
+	if l, ok := l.(Node); ok {
+		// Matching of pattern with concrete value
+		return matchNodeAST(m, l, r)
+	}
+
+	if l == nil || r == nil {
+		return nil, l == r
+	}
+
+	{
+		ln, ok1 := l.(ast.Node)
+		rn, ok2 := r.(ast.Node)
+		if ok1 && ok2 {
+			return matchAST(m, ln, rn)
+		}
+	}
+
+	{
+		obj, ok := l.(types.Object)
+		if ok {
+			switch r := r.(type) {
+			case *ast.Ident:
+				return obj, obj == m.TypesInfo.ObjectOf(r)
+			case *ast.SelectorExpr:
+				return obj, obj == m.TypesInfo.ObjectOf(r.Sel)
+			default:
+				return obj, false
+			}
+		}
+	}
+
+	{
+		ln, ok1 := l.([]ast.Expr)
+		rn, ok2 := r.([]ast.Expr)
+		if ok1 || ok2 {
+			if ok1 && !ok2 {
+				rn = []ast.Expr{r.(ast.Expr)}
+			} else if !ok1 && ok2 {
+				ln = []ast.Expr{l.(ast.Expr)}
+			}
+
+			if len(ln) != len(rn) {
+				return nil, false
+			}
+			for i, ll := range ln {
+				if _, ok := match(m, ll, rn[i]); !ok {
+					return nil, false
+				}
+			}
+			return r, true
+		}
+	}
+
+	{
+		ln, ok1 := l.([]ast.Stmt)
+		rn, ok2 := r.([]ast.Stmt)
+		if ok1 || ok2 {
+			if ok1 && !ok2 {
+				rn = []ast.Stmt{r.(ast.Stmt)}
+			} else if !ok1 && ok2 {
+				ln = []ast.Stmt{l.(ast.Stmt)}
+			}
+
+			if len(ln) != len(rn) {
+				return nil, false
+			}
+			for i, ll := range ln {
+				if _, ok := match(m, ll, rn[i]); !ok {
+					return nil, false
+				}
+			}
+			return r, true
+		}
+	}
+
+	{
+		ln, ok1 := l.([]*ast.Field)
+		rn, ok2 := r.([]*ast.Field)
+		if ok1 || ok2 {
+			if ok1 && !ok2 {
+				rn = []*ast.Field{r.(*ast.Field)}
+			} else if !ok1 && ok2 {
+				ln = []*ast.Field{l.(*ast.Field)}
+			}
+
+			if len(ln) != len(rn) {
+				return nil, false
+			}
+			for i, ll := range ln {
+				if _, ok := match(m, ll, rn[i]); !ok {
+					return nil, false
+				}
+			}
+			return r, true
+		}
+	}
+
+	panic(fmt.Sprintf("unsupported comparison: %T and %T", l, r))
+}
+
+// Match a Node with an AST node
+func matchNodeAST(m *Matcher, a Node, b interface{}) (interface{}, bool) {
+	switch b := b.(type) {
+	case []ast.Stmt:
+		// 'a' is not a List or we'd be using its Match
+		// implementation.
+
+		if len(b) != 1 {
+			return nil, false
+		}
+		return match(m, a, b[0])
+	case []ast.Expr:
+		// 'a' is not a List or we'd be using its Match
+		// implementation.
+
+		if len(b) != 1 {
+			return nil, false
+		}
+		return match(m, a, b[0])
+	case ast.Node:
+		ra := reflect.ValueOf(a)
+		rb := reflect.ValueOf(b).Elem()
+
+		if ra.Type().Name() != rb.Type().Name() {
+			return nil, false
+		}
+
+		for i := 0; i < ra.NumField(); i++ {
+			af := ra.Field(i)
+			fieldName := ra.Type().Field(i).Name
+			bf := rb.FieldByName(fieldName)
+			if (bf == reflect.Value{}) {
+				panic(fmt.Sprintf("internal error: could not find field %s in type %t when comparing with %T", fieldName, b, a))
+			}
+			ai := af.Interface()
+			bi := bf.Interface()
+			if ai == nil {
+				return b, bi == nil
+			}
+			if _, ok := match(m, ai.(Node), bi); !ok {
+				return b, false
+			}
+		}
+		return b, true
+	case nil:
+		return nil, a == Nil{}
+	default:
+		panic(fmt.Sprintf("unhandled type %T", b))
+	}
+}
+
+// Match two AST nodes
+func matchAST(m *Matcher, a, b ast.Node) (interface{}, bool) {
+	ra := reflect.ValueOf(a)
+	rb := reflect.ValueOf(b)
+
+	if ra.Type() != rb.Type() {
+		return nil, false
+	}
+	if ra.IsNil() || rb.IsNil() {
+		return rb, ra.IsNil() == rb.IsNil()
+	}
+
+	ra = ra.Elem()
+	rb = rb.Elem()
+	for i := 0; i < ra.NumField(); i++ {
+		af := ra.Field(i)
+		bf := rb.Field(i)
+		if af.Type() == rtTokPos || af.Type() == rtObject || af.Type() == rtCommentGroup {
+			continue
+		}
+
+		switch af.Kind() {
+		case reflect.Slice:
+			if af.Len() != bf.Len() {
+				return nil, false
+			}
+			for j := 0; j < af.Len(); j++ {
+				if _, ok := match(m, af.Index(j).Interface().(ast.Node), bf.Index(j).Interface().(ast.Node)); !ok {
+					return nil, false
+				}
+			}
+		case reflect.String:
+			if af.String() != bf.String() {
+				return nil, false
+			}
+		case reflect.Int:
+			if af.Int() != bf.Int() {
+				return nil, false
+			}
+		case reflect.Bool:
+			if af.Bool() != bf.Bool() {
+				return nil, false
+			}
+		case reflect.Ptr, reflect.Interface:
+			if _, ok := match(m, af.Interface(), bf.Interface()); !ok {
+				return nil, false
+			}
+		default:
+			panic(fmt.Sprintf("internal error: unhandled kind %s (%T)", af.Kind(), af.Interface()))
+		}
+	}
+	return b, true
+}
+
+func (b Binding) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	if isNil(b.Node) {
+		v, ok := m.State[b.Name]
+		if ok {
+			// Recall value
+			return match(m, v, node)
+		}
+		// Matching anything
+		b.Node = Any{}
+	}
+
+	// Store value
+	if _, ok := m.State[b.Name]; ok {
+		panic(fmt.Sprintf("binding already created: %s", b.Name))
+	}
+	new, ret := match(m, b.Node, node)
+	if ret {
+		m.State[b.Name] = new
+	}
+	return new, ret
+}
+
+func (Any) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	return node, true
+}
+
+func (l List) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	v := reflect.ValueOf(node)
+	if v.Kind() == reflect.Slice {
+		if isNil(l.Head) {
+			return node, v.Len() == 0
+		}
+		if v.Len() == 0 {
+			return nil, false
+		}
+		// OPT(dh): don't check the entire tail if head didn't match
+		_, ok1 := match(m, l.Head, v.Index(0).Interface())
+		_, ok2 := match(m, l.Tail, v.Slice(1, v.Len()).Interface())
+		return node, ok1 && ok2
+	}
+	// Our empty list does not equal an untyped Go nil. This way, we can
+	// tell apart an if with no else and an if with an empty else.
+	return nil, false
+}
+
+func (s String) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	switch o := node.(type) {
+	case token.Token:
+		if tok, ok := maybeToken(s); ok {
+			return match(m, tok, node)
+		}
+		return nil, false
+	case string:
+		return o, string(s) == o
+	case types.TypeAndValue:
+		return o, o.Value != nil && o.Value.String() == string(s)
+	default:
+		return nil, false
+	}
+}
+
+func (tok Token) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	o, ok := node.(token.Token)
+	if !ok {
+		return nil, false
+	}
+	return o, token.Token(tok) == o
+}
+
+func (Nil) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	return nil, isNil(node) || reflect.ValueOf(node).IsNil()
+}
+
+func (builtin Builtin) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	r, ok := match(m, Ident(builtin), node)
+	if !ok {
+		return nil, false
+	}
+	ident := r.(*ast.Ident)
+	obj := m.TypesInfo.ObjectOf(ident)
+	if obj != types.Universe.Lookup(ident.Name) {
+		return nil, false
+	}
+	return ident, true
+}
+
+func (obj Object) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	r, ok := match(m, Ident(obj), node)
+	if !ok {
+		return nil, false
+	}
+	ident := r.(*ast.Ident)
+
+	id := m.TypesInfo.ObjectOf(ident)
+	_, ok = match(m, obj.Name, ident.Name)
+	return id, ok
+}
+
+func (fn Function) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	var name string
+	var obj types.Object
+
+	base := []Node{
+		Ident{Any{}},
+		SelectorExpr{Any{}, Any{}},
+	}
+	p := Or{
+		Nodes: append(base,
+			IndexExpr{Or{Nodes: base}, Any{}},
+			IndexListExpr{Or{Nodes: base}, Any{}})}
+
+	r, ok := match(m, p, node)
+	if !ok {
+		return nil, false
+	}
+
+	fun := r
+	switch idx := fun.(type) {
+	case *ast.IndexExpr:
+		fun = idx.X
+	case *typeparams.IndexListExpr:
+		fun = idx.X
+	}
+
+	switch fun := fun.(type) {
+	case *ast.Ident:
+		obj = m.TypesInfo.ObjectOf(fun)
+		switch obj := obj.(type) {
+		case *types.Func:
+			// OPT(dh): optimize this similar to code.FuncName
+			name = obj.FullName()
+		case *types.Builtin:
+			name = obj.Name()
+		case *types.TypeName:
+			name = types.TypeString(obj.Type(), nil)
+		default:
+			return nil, false
+		}
+	case *ast.SelectorExpr:
+		obj = m.TypesInfo.ObjectOf(fun.Sel)
+		switch obj := obj.(type) {
+		case *types.Func:
+			// OPT(dh): optimize this similar to code.FuncName
+			name = obj.FullName()
+		case *types.TypeName:
+			name = types.TypeString(obj.Type(), nil)
+		default:
+			return nil, false
+		}
+	default:
+		panic("unreachable")
+	}
+	_, ok = match(m, fn.Name, name)
+	return obj, ok
+}
+
+func (or Or) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	for _, opt := range or.Nodes {
+		mc := m.fork()
+		if ret, ok := match(mc, opt, node); ok {
+			m.merge(mc)
+			return ret, true
+		}
+	}
+	return nil, false
+}
+
+func (not Not) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	_, ok := match(m, not.Node, node)
+	if ok {
+		return nil, false
+	}
+	return node, true
+}
+
+var integerLiteralQ = MustParse(`(Or (BasicLit "INT" _) (UnaryExpr (Or "+" "-") (IntegerLiteral _)))`)
+
+func (lit IntegerLiteral) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	matched, ok := match(m, integerLiteralQ.Root, node)
+	if !ok {
+		return nil, false
+	}
+	tv, ok := m.TypesInfo.Types[matched.(ast.Expr)]
+	if !ok {
+		return nil, false
+	}
+	if tv.Value == nil {
+		return nil, false
+	}
+	_, ok = match(m, lit.Value, tv)
+	return matched, ok
+}
+
+func (texpr TrulyConstantExpression) Match(m *Matcher, node interface{}) (interface{}, bool) {
+	expr, ok := node.(ast.Expr)
+	if !ok {
+		return nil, false
+	}
+	tv, ok := m.TypesInfo.Types[expr]
+	if !ok {
+		return nil, false
+	}
+	if tv.Value == nil {
+		return nil, false
+	}
+	truly := true
+	ast.Inspect(expr, func(node ast.Node) bool {
+		if _, ok := node.(*ast.Ident); ok {
+			truly = false
+			return false
+		}
+		return true
+	})
+	if !truly {
+		return nil, false
+	}
+	_, ok = match(m, texpr.Value, tv)
+	return expr, ok
+}
+
+var (
+	// Types of fields in go/ast structs that we want to skip
+	rtTokPos       = reflect.TypeOf(token.Pos(0))
+	rtObject       = reflect.TypeOf((*ast.Object)(nil))
+	rtCommentGroup = reflect.TypeOf((*ast.CommentGroup)(nil))
+)
+
+var (
+	_ matcher = Binding{}
+	_ matcher = Any{}
+	_ matcher = List{}
+	_ matcher = String("")
+	_ matcher = Token(0)
+	_ matcher = Nil{}
+	_ matcher = Builtin{}
+	_ matcher = Object{}
+	_ matcher = Function{}
+	_ matcher = Or{}
+	_ matcher = Not{}
+	_ matcher = IntegerLiteral{}
+	_ matcher = TrulyConstantExpression{}
+)

vendor/honnef.co/go/tools/pattern/parser.go

@@ -0,0 +1,467 @@
+package pattern
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"reflect"
+)
+
+type Pattern struct {
+	Root Node
+	// Relevant contains instances of ast.Node that could potentially
+	// initiate a successful match of the pattern.
+	Relevant []reflect.Type
+}
+
+func MustParse(s string) Pattern {
+	p := &Parser{AllowTypeInfo: true}
+	pat, err := p.Parse(s)
+	if err != nil {
+		panic(err)
+	}
+	return pat
+}
+
+func roots(node Node) []reflect.Type {
+	switch node := node.(type) {
+	case Or:
+		var out []reflect.Type
+		for _, el := range node.Nodes {
+			out = append(out, roots(el)...)
+		}
+		return out
+	case Not:
+		return roots(node.Node)
+	case Binding:
+		return roots(node.Node)
+	case Nil, nil:
+		// this branch is reached via bindings
+		return allTypes
+	default:
+		Ts, ok := nodeToASTTypes[reflect.TypeOf(node)]
+		if !ok {
+			panic(fmt.Sprintf("internal error: unhandled type %T", node))
+		}
+		return Ts
+	}
+}
+
+var allTypes = []reflect.Type{
+	reflect.TypeOf((*ast.RangeStmt)(nil)),
+	reflect.TypeOf((*ast.AssignStmt)(nil)),
+	reflect.TypeOf((*ast.IndexExpr)(nil)),
+	reflect.TypeOf((*ast.Ident)(nil)),
+	reflect.TypeOf((*ast.ValueSpec)(nil)),
+	reflect.TypeOf((*ast.GenDecl)(nil)),
+	reflect.TypeOf((*ast.BinaryExpr)(nil)),
+	reflect.TypeOf((*ast.ForStmt)(nil)),
+	reflect.TypeOf((*ast.ArrayType)(nil)),
+	reflect.TypeOf((*ast.DeferStmt)(nil)),
+	reflect.TypeOf((*ast.MapType)(nil)),
+	reflect.TypeOf((*ast.ReturnStmt)(nil)),
+	reflect.TypeOf((*ast.SliceExpr)(nil)),
+	reflect.TypeOf((*ast.StarExpr)(nil)),
+	reflect.TypeOf((*ast.UnaryExpr)(nil)),
+	reflect.TypeOf((*ast.SendStmt)(nil)),
+	reflect.TypeOf((*ast.SelectStmt)(nil)),
+	reflect.TypeOf((*ast.ImportSpec)(nil)),
+	reflect.TypeOf((*ast.IfStmt)(nil)),
+	reflect.TypeOf((*ast.GoStmt)(nil)),
+	reflect.TypeOf((*ast.Field)(nil)),
+	reflect.TypeOf((*ast.SelectorExpr)(nil)),
+	reflect.TypeOf((*ast.StructType)(nil)),
+	reflect.TypeOf((*ast.KeyValueExpr)(nil)),
+	reflect.TypeOf((*ast.FuncType)(nil)),
+	reflect.TypeOf((*ast.FuncLit)(nil)),
+	reflect.TypeOf((*ast.FuncDecl)(nil)),
+	reflect.TypeOf((*ast.ChanType)(nil)),
+	reflect.TypeOf((*ast.CallExpr)(nil)),
+	reflect.TypeOf((*ast.CaseClause)(nil)),
+	reflect.TypeOf((*ast.CommClause)(nil)),
+	reflect.TypeOf((*ast.CompositeLit)(nil)),
+	reflect.TypeOf((*ast.EmptyStmt)(nil)),
+	reflect.TypeOf((*ast.SwitchStmt)(nil)),
+	reflect.TypeOf((*ast.TypeSwitchStmt)(nil)),
+	reflect.TypeOf((*ast.TypeAssertExpr)(nil)),
+	reflect.TypeOf((*ast.TypeSpec)(nil)),
+	reflect.TypeOf((*ast.InterfaceType)(nil)),
+	reflect.TypeOf((*ast.BranchStmt)(nil)),
+	reflect.TypeOf((*ast.IncDecStmt)(nil)),
+	reflect.TypeOf((*ast.BasicLit)(nil)),
+}
+
+var nodeToASTTypes = map[reflect.Type][]reflect.Type{
+	reflect.TypeOf(String("")):                nil,
+	reflect.TypeOf(Token(0)):                  nil,
+	reflect.TypeOf(List{}):                    {reflect.TypeOf((*ast.BlockStmt)(nil)), reflect.TypeOf((*ast.FieldList)(nil))},
+	reflect.TypeOf(Builtin{}):                 {reflect.TypeOf((*ast.Ident)(nil))},
+	reflect.TypeOf(Object{}):                  {reflect.TypeOf((*ast.Ident)(nil))},
+	reflect.TypeOf(Function{}):                {reflect.TypeOf((*ast.Ident)(nil)), reflect.TypeOf((*ast.SelectorExpr)(nil))},
+	reflect.TypeOf(Any{}):                     allTypes,
+	reflect.TypeOf(RangeStmt{}):               {reflect.TypeOf((*ast.RangeStmt)(nil))},
+	reflect.TypeOf(AssignStmt{}):              {reflect.TypeOf((*ast.AssignStmt)(nil))},
+	reflect.TypeOf(IndexExpr{}):               {reflect.TypeOf((*ast.IndexExpr)(nil))},
+	reflect.TypeOf(Ident{}):                   {reflect.TypeOf((*ast.Ident)(nil))},
+	reflect.TypeOf(ValueSpec{}):               {reflect.TypeOf((*ast.ValueSpec)(nil))},
+	reflect.TypeOf(GenDecl{}):                 {reflect.TypeOf((*ast.GenDecl)(nil))},
+	reflect.TypeOf(BinaryExpr{}):              {reflect.TypeOf((*ast.BinaryExpr)(nil))},
+	reflect.TypeOf(ForStmt{}):                 {reflect.TypeOf((*ast.ForStmt)(nil))},
+	reflect.TypeOf(ArrayType{}):               {reflect.TypeOf((*ast.ArrayType)(nil))},
+	reflect.TypeOf(DeferStmt{}):               {reflect.TypeOf((*ast.DeferStmt)(nil))},
+	reflect.TypeOf(MapType{}):                 {reflect.TypeOf((*ast.MapType)(nil))},
+	reflect.TypeOf(ReturnStmt{}):              {reflect.TypeOf((*ast.ReturnStmt)(nil))},
+	reflect.TypeOf(SliceExpr{}):               {reflect.TypeOf((*ast.SliceExpr)(nil))},
+	reflect.TypeOf(StarExpr{}):                {reflect.TypeOf((*ast.StarExpr)(nil))},
+	reflect.TypeOf(UnaryExpr{}):               {reflect.TypeOf((*ast.UnaryExpr)(nil))},
+	reflect.TypeOf(SendStmt{}):                {reflect.TypeOf((*ast.SendStmt)(nil))},
+	reflect.TypeOf(SelectStmt{}):              {reflect.TypeOf((*ast.SelectStmt)(nil))},
+	reflect.TypeOf(ImportSpec{}):              {reflect.TypeOf((*ast.ImportSpec)(nil))},
+	reflect.TypeOf(IfStmt{}):                  {reflect.TypeOf((*ast.IfStmt)(nil))},
+	reflect.TypeOf(GoStmt{}):                  {reflect.TypeOf((*ast.GoStmt)(nil))},
+	reflect.TypeOf(Field{}):                   {reflect.TypeOf((*ast.Field)(nil))},
+	reflect.TypeOf(SelectorExpr{}):            {reflect.TypeOf((*ast.SelectorExpr)(nil))},
+	reflect.TypeOf(StructType{}):              {reflect.TypeOf((*ast.StructType)(nil))},
+	reflect.TypeOf(KeyValueExpr{}):            {reflect.TypeOf((*ast.KeyValueExpr)(nil))},
+	reflect.TypeOf(FuncType{}):                {reflect.TypeOf((*ast.FuncType)(nil))},
+	reflect.TypeOf(FuncLit{}):                 {reflect.TypeOf((*ast.FuncLit)(nil))},
+	reflect.TypeOf(FuncDecl{}):                {reflect.TypeOf((*ast.FuncDecl)(nil))},
+	reflect.TypeOf(ChanType{}):                {reflect.TypeOf((*ast.ChanType)(nil))},
+	reflect.TypeOf(CallExpr{}):                {reflect.TypeOf((*ast.CallExpr)(nil))},
+	reflect.TypeOf(CaseClause{}):              {reflect.TypeOf((*ast.CaseClause)(nil))},
+	reflect.TypeOf(CommClause{}):              {reflect.TypeOf((*ast.CommClause)(nil))},
+	reflect.TypeOf(CompositeLit{}):            {reflect.TypeOf((*ast.CompositeLit)(nil))},
+	reflect.TypeOf(EmptyStmt{}):               {reflect.TypeOf((*ast.EmptyStmt)(nil))},
+	reflect.TypeOf(SwitchStmt{}):              {reflect.TypeOf((*ast.SwitchStmt)(nil))},
+	reflect.TypeOf(TypeSwitchStmt{}):          {reflect.TypeOf((*ast.TypeSwitchStmt)(nil))},
+	reflect.TypeOf(TypeAssertExpr{}):          {reflect.TypeOf((*ast.TypeAssertExpr)(nil))},
+	reflect.TypeOf(TypeSpec{}):                {reflect.TypeOf((*ast.TypeSpec)(nil))},
+	reflect.TypeOf(InterfaceType{}):           {reflect.TypeOf((*ast.InterfaceType)(nil))},
+	reflect.TypeOf(BranchStmt{}):              {reflect.TypeOf((*ast.BranchStmt)(nil))},
+	reflect.TypeOf(IncDecStmt{}):              {reflect.TypeOf((*ast.IncDecStmt)(nil))},
+	reflect.TypeOf(BasicLit{}):                {reflect.TypeOf((*ast.BasicLit)(nil))},
+	reflect.TypeOf(IntegerLiteral{}):          {reflect.TypeOf((*ast.BasicLit)(nil)), reflect.TypeOf((*ast.UnaryExpr)(nil))},
+	reflect.TypeOf(TrulyConstantExpression{}): allTypes, // this is an over-approximation, which is fine
+}
+
+var requiresTypeInfo = map[string]bool{
+	"Function": true,
+	"Builtin":  true,
+	"Object":   true,
+}
+
+type Parser struct {
+	// Allow nodes that rely on type information
+	AllowTypeInfo bool
+
+	lex   *lexer
+	cur   item
+	last  *item
+	items chan item
+}
+
+func (p *Parser) Parse(s string) (Pattern, error) {
+	p.cur = item{}
+	p.last = nil
+	p.items = nil
+
+	fset := token.NewFileSet()
+	p.lex = &lexer{
+		f:     fset.AddFile("<input>", -1, len(s)),
+		input: s,
+		items: make(chan item),
+	}
+	go p.lex.run()
+	p.items = p.lex.items
+	root, err := p.node()
+	if err != nil {
+		// drain lexer if parsing failed
+		for range p.lex.items {
+		}
+		return Pattern{}, err
+	}
+	if item := <-p.lex.items; item.typ != itemEOF {
+		return Pattern{}, fmt.Errorf("unexpected token %s after end of pattern", item.typ)
+	}
+	return Pattern{
+		Root:     root,
+		Relevant: roots(root),
+	}, nil
+}
+
+func (p *Parser) next() item {
+	if p.last != nil {
+		n := *p.last
+		p.last = nil
+		return n
+	}
+	var ok bool
+	p.cur, ok = <-p.items
+	if !ok {
+		p.cur = item{typ: eof}
+	}
+	return p.cur
+}
+
+func (p *Parser) rewind() {
+	p.last = &p.cur
+}
+
+func (p *Parser) peek() item {
+	n := p.next()
+	p.rewind()
+	return n
+}
+
+func (p *Parser) accept(typ itemType) (item, bool) {
+	n := p.next()
+	if n.typ == typ {
+		return n, true
+	}
+	p.rewind()
+	return item{}, false
+}
+
+func (p *Parser) unexpectedToken(valid string) error {
+	if p.cur.typ == itemError {
+		return fmt.Errorf("error lexing input: %s", p.cur.val)
+	}
+	var got string
+	switch p.cur.typ {
+	case itemTypeName, itemVariable, itemString:
+		got = p.cur.val
+	default:
+		got = "'" + p.cur.typ.String() + "'"
+	}
+
+	pos := p.lex.f.Position(token.Pos(p.cur.pos))
+	return fmt.Errorf("%s: expected %s, found %s", pos, valid, got)
+}
+
+func (p *Parser) node() (Node, error) {
+	if _, ok := p.accept(itemLeftParen); !ok {
+		return nil, p.unexpectedToken("'('")
+	}
+	typ, ok := p.accept(itemTypeName)
+	if !ok {
+		return nil, p.unexpectedToken("Node type")
+	}
+
+	var objs []Node
+	for {
+		if _, ok := p.accept(itemRightParen); ok {
+			break
+		} else {
+			p.rewind()
+			obj, err := p.object()
+			if err != nil {
+				return nil, err
+			}
+			objs = append(objs, obj)
+		}
+	}
+
+	return p.populateNode(typ.val, objs)
+}
+
+func populateNode(typ string, objs []Node, allowTypeInfo bool) (Node, error) {
+	T, ok := structNodes[typ]
+	if !ok {
+		return nil, fmt.Errorf("unknown node %s", typ)
+	}
+
+	if !allowTypeInfo && requiresTypeInfo[typ] {
+		return nil, fmt.Errorf("Node %s requires type information", typ)
+	}
+
+	pv := reflect.New(T)
+	v := pv.Elem()
+
+	if v.NumField() == 1 {
+		f := v.Field(0)
+		if f.Type().Kind() == reflect.Slice {
+			// Variadic node
+			f.Set(reflect.AppendSlice(f, reflect.ValueOf(objs)))
+			return v.Interface().(Node), nil
+		}
+	}
+	if len(objs) != v.NumField() {
+		return nil, fmt.Errorf("tried to initialize node %s with %d values, expected %d", typ, len(objs), v.NumField())
+	}
+	for i := 0; i < v.NumField(); i++ {
+		f := v.Field(i)
+		if f.Kind() == reflect.String {
+			if obj, ok := objs[i].(String); ok {
+				f.Set(reflect.ValueOf(string(obj)))
+			} else {
+				return nil, fmt.Errorf("first argument of (Binding name node) must be string, but got %s", objs[i])
+			}
+		} else {
+			f.Set(reflect.ValueOf(objs[i]))
+		}
+	}
+	return v.Interface().(Node), nil
+}
+
+func (p *Parser) populateNode(typ string, objs []Node) (Node, error) {
+	return populateNode(typ, objs, p.AllowTypeInfo)
+}
+
+var structNodes = map[string]reflect.Type{
+	"Any":                     reflect.TypeOf(Any{}),
+	"Ellipsis":                reflect.TypeOf(Ellipsis{}),
+	"List":                    reflect.TypeOf(List{}),
+	"Binding":                 reflect.TypeOf(Binding{}),
+	"RangeStmt":               reflect.TypeOf(RangeStmt{}),
+	"AssignStmt":              reflect.TypeOf(AssignStmt{}),
+	"IndexExpr":               reflect.TypeOf(IndexExpr{}),
+	"Ident":                   reflect.TypeOf(Ident{}),
+	"Builtin":                 reflect.TypeOf(Builtin{}),
+	"ValueSpec":               reflect.TypeOf(ValueSpec{}),
+	"GenDecl":                 reflect.TypeOf(GenDecl{}),
+	"BinaryExpr":              reflect.TypeOf(BinaryExpr{}),
+	"ForStmt":                 reflect.TypeOf(ForStmt{}),
+	"ArrayType":               reflect.TypeOf(ArrayType{}),
+	"DeferStmt":               reflect.TypeOf(DeferStmt{}),
+	"MapType":                 reflect.TypeOf(MapType{}),
+	"ReturnStmt":              reflect.TypeOf(ReturnStmt{}),
+	"SliceExpr":               reflect.TypeOf(SliceExpr{}),
+	"StarExpr":                reflect.TypeOf(StarExpr{}),
+	"UnaryExpr":               reflect.TypeOf(UnaryExpr{}),
+	"SendStmt":                reflect.TypeOf(SendStmt{}),
+	"SelectStmt":              reflect.TypeOf(SelectStmt{}),
+	"ImportSpec":              reflect.TypeOf(ImportSpec{}),
+	"IfStmt":                  reflect.TypeOf(IfStmt{}),
+	"GoStmt":                  reflect.TypeOf(GoStmt{}),
+	"Field":                   reflect.TypeOf(Field{}),
+	"SelectorExpr":            reflect.TypeOf(SelectorExpr{}),
+	"StructType":              reflect.TypeOf(StructType{}),
+	"KeyValueExpr":            reflect.TypeOf(KeyValueExpr{}),
+	"FuncType":                reflect.TypeOf(FuncType{}),
+	"FuncLit":                 reflect.TypeOf(FuncLit{}),
+	"FuncDecl":                reflect.TypeOf(FuncDecl{}),
+	"ChanType":                reflect.TypeOf(ChanType{}),
+	"CallExpr":                reflect.TypeOf(CallExpr{}),
+	"CaseClause":              reflect.TypeOf(CaseClause{}),
+	"CommClause":              reflect.TypeOf(CommClause{}),
+	"CompositeLit":            reflect.TypeOf(CompositeLit{}),
+	"EmptyStmt":               reflect.TypeOf(EmptyStmt{}),
+	"SwitchStmt":              reflect.TypeOf(SwitchStmt{}),
+	"TypeSwitchStmt":          reflect.TypeOf(TypeSwitchStmt{}),
+	"TypeAssertExpr":          reflect.TypeOf(TypeAssertExpr{}),
+	"TypeSpec":                reflect.TypeOf(TypeSpec{}),
+	"InterfaceType":           reflect.TypeOf(InterfaceType{}),
+	"BranchStmt":              reflect.TypeOf(BranchStmt{}),
+	"IncDecStmt":              reflect.TypeOf(IncDecStmt{}),
+	"BasicLit":                reflect.TypeOf(BasicLit{}),
+	"Object":                  reflect.TypeOf(Object{}),
+	"Function":                reflect.TypeOf(Function{}),
+	"Or":                      reflect.TypeOf(Or{}),
+	"Not":                     reflect.TypeOf(Not{}),
+	"IntegerLiteral":          reflect.TypeOf(IntegerLiteral{}),
+	"TrulyConstantExpression": reflect.TypeOf(TrulyConstantExpression{}),
+}
+
+func (p *Parser) object() (Node, error) {
+	n := p.next()
+	switch n.typ {
+	case itemLeftParen:
+		p.rewind()
+		node, err := p.node()
+		if err != nil {
+			return node, err
+		}
+		if p.peek().typ == itemColon {
+			p.next()
+			tail, err := p.object()
+			if err != nil {
+				return node, err
+			}
+			return List{Head: node, Tail: tail}, nil
+		}
+		return node, nil
+	case itemLeftBracket:
+		p.rewind()
+		return p.array()
+	case itemVariable:
+		v := n
+		if v.val == "nil" {
+			return Nil{}, nil
+		}
+		var b Binding
+		if _, ok := p.accept(itemAt); ok {
+			o, err := p.node()
+			if err != nil {
+				return nil, err
+			}
+			b = Binding{
+				Name: v.val,
+				Node: o,
+			}
+		} else {
+			p.rewind()
+			b = Binding{Name: v.val}
+		}
+		if p.peek().typ == itemColon {
+			p.next()
+			tail, err := p.object()
+			if err != nil {
+				return b, err
+			}
+			return List{Head: b, Tail: tail}, nil
+		}
+		return b, nil
+	case itemBlank:
+		if p.peek().typ == itemColon {
+			p.next()
+			tail, err := p.object()
+			if err != nil {
+				return Any{}, err
+			}
+			return List{Head: Any{}, Tail: tail}, nil
+		}
+		return Any{}, nil
+	case itemString:
+		return String(n.val), nil
+	default:
+		return nil, p.unexpectedToken("object")
+	}
+}
+
+func (p *Parser) array() (Node, error) {
+	if _, ok := p.accept(itemLeftBracket); !ok {
+		return nil, p.unexpectedToken("'['")
+	}
+
+	var objs []Node
+	for {
+		if _, ok := p.accept(itemRightBracket); ok {
+			break
+		} else {
+			p.rewind()
+			obj, err := p.object()
+			if err != nil {
+				return nil, err
+			}
+			objs = append(objs, obj)
+		}
+	}
+
+	tail := List{}
+	for i := len(objs) - 1; i >= 0; i-- {
+		l := List{
+			Head: objs[i],
+			Tail: tail,
+		}
+		tail = l
+	}
+	return tail, nil
+}
+
+/*
+Node ::= itemLeftParen itemTypeName Object* itemRightParen
+Object ::= Node | Array | Binding | itemVariable | itemBlank | itemString
+Array := itemLeftBracket Object* itemRightBracket
+Array := Object itemColon Object
+Binding ::= itemVariable itemAt Node
+*/

vendor/honnef.co/go/tools/pattern/pattern.go

@@ -0,0 +1,522 @@
+package pattern
+
+import (
+	"fmt"
+	"go/token"
+	"reflect"
+	"strings"
+)
+
+var (
+	_ Node = Ellipsis{}
+	_ Node = Binding{}
+	_ Node = RangeStmt{}
+	_ Node = AssignStmt{}
+	_ Node = IndexExpr{}
+	_ Node = IndexListExpr{}
+	_ Node = Ident{}
+	_ Node = Builtin{}
+	_ Node = String("")
+	_ Node = Any{}
+	_ Node = ValueSpec{}
+	_ Node = List{}
+	_ Node = GenDecl{}
+	_ Node = BinaryExpr{}
+	_ Node = ForStmt{}
+	_ Node = ArrayType{}
+	_ Node = DeferStmt{}
+	_ Node = MapType{}
+	_ Node = ReturnStmt{}
+	_ Node = SliceExpr{}
+	_ Node = StarExpr{}
+	_ Node = UnaryExpr{}
+	_ Node = SendStmt{}
+	_ Node = SelectStmt{}
+	_ Node = ImportSpec{}
+	_ Node = IfStmt{}
+	_ Node = GoStmt{}
+	_ Node = Field{}
+	_ Node = SelectorExpr{}
+	_ Node = StructType{}
+	_ Node = KeyValueExpr{}
+	_ Node = FuncType{}
+	_ Node = FuncLit{}
+	_ Node = FuncDecl{}
+	_ Node = Token(0)
+	_ Node = ChanType{}
+	_ Node = CallExpr{}
+	_ Node = CaseClause{}
+	_ Node = CommClause{}
+	_ Node = CompositeLit{}
+	_ Node = EmptyStmt{}
+	_ Node = SwitchStmt{}
+	_ Node = TypeSwitchStmt{}
+	_ Node = TypeAssertExpr{}
+	_ Node = TypeSpec{}
+	_ Node = InterfaceType{}
+	_ Node = BranchStmt{}
+	_ Node = IncDecStmt{}
+	_ Node = BasicLit{}
+	_ Node = Nil{}
+	_ Node = Object{}
+	_ Node = Function{}
+	_ Node = Not{}
+	_ Node = Or{}
+	_ Node = IntegerLiteral{}
+	_ Node = TrulyConstantExpression{}
+)
+
+type Function struct {
+	Name Node
+}
+
+type Token token.Token
+
+type Nil struct {
+}
+
+type Ellipsis struct {
+	Elt Node
+}
+
+type IncDecStmt struct {
+	X   Node
+	Tok Node
+}
+
+type BranchStmt struct {
+	Tok   Node
+	Label Node
+}
+
+type InterfaceType struct {
+	Methods Node
+}
+
+type TypeSpec struct {
+	Name Node
+	Type Node
+}
+
+type TypeAssertExpr struct {
+	X    Node
+	Type Node
+}
+
+type TypeSwitchStmt struct {
+	Init   Node
+	Assign Node
+	Body   Node
+}
+
+type SwitchStmt struct {
+	Init Node
+	Tag  Node
+	Body Node
+}
+
+type EmptyStmt struct {
+}
+
+type CompositeLit struct {
+	Type Node
+	Elts Node
+}
+
+type CommClause struct {
+	Comm Node
+	Body Node
+}
+
+type CaseClause struct {
+	List Node
+	Body Node
+}
+
+type CallExpr struct {
+	Fun  Node
+	Args Node
+	// XXX handle ellipsis
+}
+
+// TODO(dh): add a ChanDir node, and a way of instantiating it.
+
+type ChanType struct {
+	Dir   Node
+	Value Node
+}
+
+type FuncDecl struct {
+	Recv Node
+	Name Node
+	Type Node
+	Body Node
+}
+
+type FuncLit struct {
+	Type Node
+	Body Node
+}
+
+type FuncType struct {
+	Params  Node
+	Results Node
+}
+
+type KeyValueExpr struct {
+	Key   Node
+	Value Node
+}
+
+type StructType struct {
+	Fields Node
+}
+
+type SelectorExpr struct {
+	X   Node
+	Sel Node
+}
+
+type Field struct {
+	Names Node
+	Type  Node
+	Tag   Node
+}
+
+type GoStmt struct {
+	Call Node
+}
+
+type IfStmt struct {
+	Init Node
+	Cond Node
+	Body Node
+	Else Node
+}
+
+type ImportSpec struct {
+	Name Node
+	Path Node
+}
+
+type SelectStmt struct {
+	Body Node
+}
+
+type ArrayType struct {
+	Len Node
+	Elt Node
+}
+
+type DeferStmt struct {
+	Call Node
+}
+
+type MapType struct {
+	Key   Node
+	Value Node
+}
+
+type ReturnStmt struct {
+	Results Node
+}
+
+type SliceExpr struct {
+	X    Node
+	Low  Node
+	High Node
+	Max  Node
+}
+
+type StarExpr struct {
+	X Node
+}
+
+type UnaryExpr struct {
+	Op Node
+	X  Node
+}
+
+type SendStmt struct {
+	Chan  Node
+	Value Node
+}
+
+type Binding struct {
+	Name string
+	Node Node
+}
+
+type RangeStmt struct {
+	Key   Node
+	Value Node
+	Tok   Node
+	X     Node
+	Body  Node
+}
+
+type AssignStmt struct {
+	Lhs Node
+	Tok Node
+	Rhs Node
+}
+
+type IndexExpr struct {
+	X     Node
+	Index Node
+}
+
+type IndexListExpr struct {
+	X       Node
+	Indices Node
+}
+
+type Node interface {
+	String() string
+	isNode()
+}
+
+type Ident struct {
+	Name Node
+}
+
+type Object struct {
+	Name Node
+}
+
+type Builtin struct {
+	Name Node
+}
+
+type String string
+
+type Any struct{}
+
+type ValueSpec struct {
+	Names  Node
+	Type   Node
+	Values Node
+}
+
+type List struct {
+	Head Node
+	Tail Node
+}
+
+type GenDecl struct {
+	Tok   Node
+	Specs Node
+}
+
+type BasicLit struct {
+	Kind  Node
+	Value Node
+}
+
+// An IntegerLiteral is a constant expression made up of only integer basic literals and the "+" and "-" unary operators.
+// That is, 0, -4, -+42 are all integer literals, but 1 + 2 is not.
+type IntegerLiteral struct {
+	Value Node
+}
+
+type BinaryExpr struct {
+	X  Node
+	Op Node
+	Y  Node
+}
+
+type ForStmt struct {
+	Init Node
+	Cond Node
+	Post Node
+	Body Node
+}
+
+type Or struct {
+	Nodes []Node
+}
+
+type Not struct {
+	Node Node
+}
+
+// A TrulyConstantExpression is a constant expression that does not make use of any identifiers.
+// It is constant even under varying build tags.
+type TrulyConstantExpression struct {
+	Value Node
+}
+
+func stringify(n Node) string {
+	v := reflect.ValueOf(n)
+	var parts []string
+	parts = append(parts, v.Type().Name())
+	for i := 0; i < v.NumField(); i++ {
+		parts = append(parts, fmt.Sprintf("%s", v.Field(i)))
+	}
+	return "(" + strings.Join(parts, " ") + ")"
+}
+
+func (stmt AssignStmt) String() string              { return stringify(stmt) }
+func (expr IndexExpr) String() string               { return stringify(expr) }
+func (expr IndexListExpr) String() string           { return stringify(expr) }
+func (id Ident) String() string                     { return stringify(id) }
+func (spec ValueSpec) String() string               { return stringify(spec) }
+func (decl GenDecl) String() string                 { return stringify(decl) }
+func (lit BasicLit) String() string                 { return stringify(lit) }
+func (expr BinaryExpr) String() string              { return stringify(expr) }
+func (stmt ForStmt) String() string                 { return stringify(stmt) }
+func (stmt RangeStmt) String() string               { return stringify(stmt) }
+func (typ ArrayType) String() string                { return stringify(typ) }
+func (stmt DeferStmt) String() string               { return stringify(stmt) }
+func (typ MapType) String() string                  { return stringify(typ) }
+func (stmt ReturnStmt) String() string              { return stringify(stmt) }
+func (expr SliceExpr) String() string               { return stringify(expr) }
+func (expr StarExpr) String() string                { return stringify(expr) }
+func (expr UnaryExpr) String() string               { return stringify(expr) }
+func (stmt SendStmt) String() string                { return stringify(stmt) }
+func (spec ImportSpec) String() string              { return stringify(spec) }
+func (stmt SelectStmt) String() string              { return stringify(stmt) }
+func (stmt IfStmt) String() string                  { return stringify(stmt) }
+func (stmt IncDecStmt) String() string              { return stringify(stmt) }
+func (stmt GoStmt) String() string                  { return stringify(stmt) }
+func (field Field) String() string                  { return stringify(field) }
+func (expr SelectorExpr) String() string            { return stringify(expr) }
+func (typ StructType) String() string               { return stringify(typ) }
+func (expr KeyValueExpr) String() string            { return stringify(expr) }
+func (typ FuncType) String() string                 { return stringify(typ) }
+func (lit FuncLit) String() string                  { return stringify(lit) }
+func (decl FuncDecl) String() string                { return stringify(decl) }
+func (stmt BranchStmt) String() string              { return stringify(stmt) }
+func (expr CallExpr) String() string                { return stringify(expr) }
+func (clause CaseClause) String() string            { return stringify(clause) }
+func (typ ChanType) String() string                 { return stringify(typ) }
+func (clause CommClause) String() string            { return stringify(clause) }
+func (lit CompositeLit) String() string             { return stringify(lit) }
+func (stmt EmptyStmt) String() string               { return stringify(stmt) }
+func (typ InterfaceType) String() string            { return stringify(typ) }
+func (stmt SwitchStmt) String() string              { return stringify(stmt) }
+func (expr TypeAssertExpr) String() string          { return stringify(expr) }
+func (spec TypeSpec) String() string                { return stringify(spec) }
+func (stmt TypeSwitchStmt) String() string          { return stringify(stmt) }
+func (nil Nil) String() string                      { return "nil" }
+func (builtin Builtin) String() string              { return stringify(builtin) }
+func (obj Object) String() string                   { return stringify(obj) }
+func (fn Function) String() string                  { return stringify(fn) }
+func (el Ellipsis) String() string                  { return stringify(el) }
+func (not Not) String() string                      { return stringify(not) }
+func (lit IntegerLiteral) String() string           { return stringify(lit) }
+func (expr TrulyConstantExpression) String() string { return stringify(expr) }
+
+func (or Or) String() string {
+	s := "(Or"
+	for _, node := range or.Nodes {
+		s += " "
+		s += node.String()
+	}
+	s += ")"
+	return s
+}
+
+func isProperList(l List) bool {
+	if l.Head == nil && l.Tail == nil {
+		return true
+	}
+	switch tail := l.Tail.(type) {
+	case nil:
+		return false
+	case List:
+		return isProperList(tail)
+	default:
+		return false
+	}
+}
+
+func (l List) String() string {
+	if l.Head == nil && l.Tail == nil {
+		return "[]"
+	}
+
+	if isProperList(l) {
+		// pretty-print the list
+		var objs []string
+		for l.Head != nil {
+			objs = append(objs, l.Head.String())
+			l = l.Tail.(List)
+		}
+		return fmt.Sprintf("[%s]", strings.Join(objs, " "))
+	}
+
+	return fmt.Sprintf("%s:%s", l.Head, l.Tail)
+}
+
+func (bind Binding) String() string {
+	if bind.Node == nil {
+		return bind.Name
+	}
+	return fmt.Sprintf("%s@%s", bind.Name, bind.Node)
+}
+
+func (s String) String() string { return fmt.Sprintf("%q", string(s)) }
+
+func (tok Token) String() string {
+	return fmt.Sprintf("%q", strings.ToUpper(token.Token(tok).String()))
+}
+
+func (Any) String() string { return "_" }
+
+func (AssignStmt) isNode()              {}
+func (IndexExpr) isNode()               {}
+func (IndexListExpr) isNode()           {}
+func (Ident) isNode()                   {}
+func (ValueSpec) isNode()               {}
+func (GenDecl) isNode()                 {}
+func (BasicLit) isNode()                {}
+func (BinaryExpr) isNode()              {}
+func (ForStmt) isNode()                 {}
+func (RangeStmt) isNode()               {}
+func (ArrayType) isNode()               {}
+func (DeferStmt) isNode()               {}
+func (MapType) isNode()                 {}
+func (ReturnStmt) isNode()              {}
+func (SliceExpr) isNode()               {}
+func (StarExpr) isNode()                {}
+func (UnaryExpr) isNode()               {}
+func (SendStmt) isNode()                {}
+func (ImportSpec) isNode()              {}
+func (SelectStmt) isNode()              {}
+func (IfStmt) isNode()                  {}
+func (IncDecStmt) isNode()              {}
+func (GoStmt) isNode()                  {}
+func (Field) isNode()                   {}
+func (SelectorExpr) isNode()            {}
+func (StructType) isNode()              {}
+func (KeyValueExpr) isNode()            {}
+func (FuncType) isNode()                {}
+func (FuncLit) isNode()                 {}
+func (FuncDecl) isNode()                {}
+func (BranchStmt) isNode()              {}
+func (CallExpr) isNode()                {}
+func (CaseClause) isNode()              {}
+func (ChanType) isNode()                {}
+func (CommClause) isNode()              {}
+func (CompositeLit) isNode()            {}
+func (EmptyStmt) isNode()               {}
+func (InterfaceType) isNode()           {}
+func (SwitchStmt) isNode()              {}
+func (TypeAssertExpr) isNode()          {}
+func (TypeSpec) isNode()                {}
+func (TypeSwitchStmt) isNode()          {}
+func (Nil) isNode()                     {}
+func (Builtin) isNode()                 {}
+func (Object) isNode()                  {}
+func (Function) isNode()                {}
+func (Ellipsis) isNode()                {}
+func (Or) isNode()                      {}
+func (List) isNode()                    {}
+func (String) isNode()                  {}
+func (Token) isNode()                   {}
+func (Any) isNode()                     {}
+func (Binding) isNode()                 {}
+func (Not) isNode()                     {}
+func (IntegerLiteral) isNode()          {}
+func (TrulyConstantExpression) isNode() {}

vendor/honnef.co/go/tools/printf/fuzz.go

@@ -0,0 +1,12 @@
+//go:build gofuzz
+// +build gofuzz
+
+package printf
+
+func Fuzz(data []byte) int {
+	_, err := Parse(string(data))
+	if err == nil {
+		return 1
+	}
+	return 0
+}

vendor/honnef.co/go/tools/printf/printf.go

@@ -0,0 +1,197 @@
+// Package printf implements a parser for fmt.Printf-style format
+// strings.
+//
+// It parses verbs according to the following syntax:
+//     Numeric -> '0'-'9'
+//     Letter -> 'a'-'z' | 'A'-'Z'
+//     Index -> '[' Numeric+ ']'
+//     Star -> '*'
+//     Star -> Index '*'
+//
+//     Precision -> Numeric+ | Star
+//     Width -> Numeric+ | Star
+//
+//     WidthAndPrecision -> Width '.' Precision
+//     WidthAndPrecision -> Width '.'
+//     WidthAndPrecision -> Width
+//     WidthAndPrecision -> '.' Precision
+//     WidthAndPrecision -> '.'
+//
+//     Flag -> '+' | '-' | '#' | ' ' | '0'
+//     Verb -> Letter | '%'
+//
+//     Input -> '%' [ Flag+ ] [ WidthAndPrecision ] [ Index ] Verb
+package printf
+
+import (
+	"errors"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// ErrInvalid is returned for invalid format strings or verbs.
+var ErrInvalid = errors.New("invalid format string")
+
+type Verb struct {
+	Letter rune
+	Flags  string
+
+	Width     Argument
+	Precision Argument
+	// Which value in the argument list the verb uses.
+	// -1 denotes the next argument,
+	// values > 0 denote explicit arguments.
+	// The value 0 denotes that no argument is consumed. This is the case for %%.
+	Value int
+
+	Raw string
+}
+
+// Argument is an implicit or explicit width or precision.
+type Argument interface {
+	isArgument()
+}
+
+// The Default value, when no width or precision is provided.
+type Default struct{}
+
+// Zero is the implicit zero value.
+// This value may only appear for precisions in format strings like %6.f
+type Zero struct{}
+
+// Star is a * value, which may either refer to the next argument (Index == -1) or an explicit argument.
+type Star struct{ Index int }
+
+// A Literal value, such as 6 in %6d.
+type Literal int
+
+func (Default) isArgument() {}
+func (Zero) isArgument()    {}
+func (Star) isArgument()    {}
+func (Literal) isArgument() {}
+
+// Parse parses f and returns a list of actions.
+// An action may either be a literal string, or a Verb.
+func Parse(f string) ([]interface{}, error) {
+	var out []interface{}
+	for len(f) > 0 {
+		if f[0] == '%' {
+			v, n, err := ParseVerb(f)
+			if err != nil {
+				return nil, err
+			}
+			f = f[n:]
+			out = append(out, v)
+		} else {
+			n := strings.IndexByte(f, '%')
+			if n > -1 {
+				out = append(out, f[:n])
+				f = f[n:]
+			} else {
+				out = append(out, f)
+				f = ""
+			}
+		}
+	}
+
+	return out, nil
+}
+
+func atoi(s string) int {
+	n, _ := strconv.Atoi(s)
+	return n
+}
+
+// ParseVerb parses the verb at the beginning of f.
+// It returns the verb, how much of the input was consumed, and an error, if any.
+func ParseVerb(f string) (Verb, int, error) {
+	if len(f) < 2 {
+		return Verb{}, 0, ErrInvalid
+	}
+	const (
+		flags = 1
+
+		width      = 2
+		widthStar  = 3
+		widthIndex = 5
+
+		dot       = 6
+		prec      = 7
+		precStar  = 8
+		precIndex = 10
+
+		verbIndex = 11
+		verb      = 12
+	)
+
+	m := re.FindStringSubmatch(f)
+	if m == nil {
+		return Verb{}, 0, ErrInvalid
+	}
+
+	v := Verb{
+		Letter: []rune(m[verb])[0],
+		Flags:  m[flags],
+		Raw:    m[0],
+	}
+
+	if m[width] != "" {
+		// Literal width
+		v.Width = Literal(atoi(m[width]))
+	} else if m[widthStar] != "" {
+		// Star width
+		if m[widthIndex] != "" {
+			v.Width = Star{atoi(m[widthIndex])}
+		} else {
+			v.Width = Star{-1}
+		}
+	} else {
+		// Default width
+		v.Width = Default{}
+	}
+
+	if m[dot] == "" {
+		// default precision
+		v.Precision = Default{}
+	} else {
+		if m[prec] != "" {
+			// Literal precision
+			v.Precision = Literal(atoi(m[prec]))
+		} else if m[precStar] != "" {
+			// Star precision
+			if m[precIndex] != "" {
+				v.Precision = Star{atoi(m[precIndex])}
+			} else {
+				v.Precision = Star{-1}
+			}
+		} else {
+			// Zero precision
+			v.Precision = Zero{}
+		}
+	}
+
+	if m[verb] == "%" {
+		v.Value = 0
+	} else if m[verbIndex] != "" {
+		v.Value = atoi(m[verbIndex])
+	} else {
+		v.Value = -1
+	}
+
+	return v, len(m[0]), nil
+}
+
+const (
+	flags             = `([+#0 -]*)`
+	verb              = `([a-zA-Z%])`
+	index             = `(?:\[([0-9]+)\])`
+	star              = `((` + index + `)?\*)`
+	width1            = `([0-9]+)`
+	width2            = star
+	width             = `(?:` + width1 + `|` + width2 + `)`
+	precision         = width
+	widthAndPrecision = `(?:(?:` + width + `)?(?:(\.)(?:` + precision + `)?)?)`
+)
+
+var re = regexp.MustCompile(`^%` + flags + widthAndPrecision + `?` + index + `?` + verb)