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/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
+}