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/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
+}