From 762eb40892061b43a2dabbfd99486e9940a149b9 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Fri, 13 Jan 2017 13:52:44 -0500
Subject: [PATCH] cmd/go: split out cmd/go/internal/str

This is one CL in a long sequence of changes to break up the
go command from one package into a plausible group of packages.

This sequence is concerned only with moving code, not changing
or cleaning up code. There will still be more cleanup after this sequence.

The entire sequence will be submitted together: it is not a goal
for the tree to build at every step.

For #18653.

Change-Id: I63f578f5ac99c707b599ac5659293c46b275567d
Reviewed-on: https://go-review.googlesource.com/36190
Reviewed-by: David Crawshaw <crawshaw@golang.org>
---
 src/cmd/go/build.go            | 35 ++++++------
 src/cmd/go/fix.go              |  4 +-
 src/cmd/go/fmt.go              |  3 +-
 src/cmd/go/get.go              |  5 +-
 src/cmd/go/internal/str/str.go | 97 ++++++++++++++++++++++++++++++++++
 src/cmd/go/main.go             | 77 +--------------------------
 src/cmd/go/pkg.go              | 15 +++---
 src/cmd/go/pkg_test.go         | 13 ++---
 src/cmd/go/run.go              |  3 +-
 src/cmd/go/test.go             | 18 ++-----
 src/cmd/go/vet.go              | 10 ++--
 11 files changed, 154 insertions(+), 126 deletions(-)
 create mode 100644 src/cmd/go/internal/str/str.go

diff --git a/src/cmd/go/build.go b/src/cmd/go/build.go
index d00090cf19..3cd6dca17d 100644
--- a/src/cmd/go/build.go
+++ b/src/cmd/go/build.go
@@ -7,6 +7,7 @@ package main
 import (
 	"bufio"
 	"bytes"
+	"cmd/go/internal/str"
 	"container/heap"
 	"debug/elf"
 	"errors"
@@ -2091,7 +2092,7 @@ func (b *builder) run(dir string, desc string, env []string, cmdargs ...interfac
 	out, err := b.runOut(dir, desc, env, cmdargs...)
 	if len(out) > 0 {
 		if desc == "" {
-			desc = b.fmtcmd(dir, "%s", strings.Join(stringList(cmdargs...), " "))
+			desc = b.fmtcmd(dir, "%s", strings.Join(str.StringList(cmdargs...), " "))
 		}
 		b.showOutput(dir, desc, b.processOutput(out))
 		if err != nil {
@@ -2121,7 +2122,7 @@ func (b *builder) processOutput(out []byte) string {
 // runOut runs the command given by cmdline in the directory dir.
 // It returns the command output and any errors that occurred.
 func (b *builder) runOut(dir string, desc string, env []string, cmdargs ...interface{}) ([]byte, error) {
-	cmdline := stringList(cmdargs...)
+	cmdline := str.StringList(cmdargs...)
 	if buildN || buildX {
 		var envcmdline string
 		for i := range env {
@@ -2450,7 +2451,7 @@ func toolVerify(b *builder, p *Package, newTool string, ofile string, args []int
 		return err
 	}
 	if !bytes.Equal(data1, data2) {
-		return fmt.Errorf("%s and %s produced different output files:\n%s\n%s", filepath.Base(args[1].(string)), newTool, strings.Join(stringList(args...), " "), strings.Join(stringList(newArgs...), " "))
+		return fmt.Errorf("%s and %s produced different output files:\n%s\n%s", filepath.Base(args[1].(string)), newTool, strings.Join(str.StringList(args...), " "), strings.Join(str.StringList(newArgs...), " "))
 	}
 	os.Remove(ofile + ".new")
 	return nil
@@ -2477,7 +2478,7 @@ func (gcToolchain) pack(b *builder, p *Package, objDir, afile string, ofiles []s
 	}
 
 	if buildN || buildX {
-		cmdline := stringList("pack", "r", absAfile, absOfiles)
+		cmdline := str.StringList("pack", "r", absAfile, absOfiles)
 		b.showcmd(p.Dir, "%s # internal", joinUnambiguously(cmdline))
 	}
 	if buildN {
@@ -2692,7 +2693,7 @@ func (tools gccgoToolchain) gc(b *builder, p *Package, archive, obj string, asmh
 	if p.localPrefix != "" {
 		gcargs = append(gcargs, "-fgo-relative-import-path="+p.localPrefix)
 	}
-	args := stringList(tools.compiler(), importArgs, "-c", gcargs, "-o", ofile, buildGccgoflags)
+	args := str.StringList(tools.compiler(), importArgs, "-c", gcargs, "-o", ofile, buildGccgoflags)
 	for _, f := range gofiles {
 		args = append(args, mkAbs(p.Dir, f))
 	}
@@ -2913,7 +2914,7 @@ func (tools gccgoToolchain) link(b *builder, root *action, out string, allaction
 		ldflags = append(ldflags, root.p.CgoLDFLAGS...)
 	}
 
-	ldflags = stringList("-Wl,-(", ldflags, "-Wl,-)")
+	ldflags = str.StringList("-Wl,-(", ldflags, "-Wl,-)")
 
 	for _, shlib := range shlibs {
 		ldflags = append(
@@ -3244,11 +3245,11 @@ func envList(key, def string) []string {
 func (b *builder) cflags(p *Package) (cppflags, cflags, cxxflags, fflags, ldflags []string) {
 	defaults := "-g -O2"
 
-	cppflags = stringList(envList("CGO_CPPFLAGS", ""), p.CgoCPPFLAGS)
-	cflags = stringList(envList("CGO_CFLAGS", defaults), p.CgoCFLAGS)
-	cxxflags = stringList(envList("CGO_CXXFLAGS", defaults), p.CgoCXXFLAGS)
-	fflags = stringList(envList("CGO_FFLAGS", defaults), p.CgoFFLAGS)
-	ldflags = stringList(envList("CGO_LDFLAGS", defaults), p.CgoLDFLAGS)
+	cppflags = str.StringList(envList("CGO_CPPFLAGS", ""), p.CgoCPPFLAGS)
+	cflags = str.StringList(envList("CGO_CFLAGS", defaults), p.CgoCFLAGS)
+	cxxflags = str.StringList(envList("CGO_CXXFLAGS", defaults), p.CgoCXXFLAGS)
+	fflags = str.StringList(envList("CGO_FFLAGS", defaults), p.CgoFFLAGS)
+	ldflags = str.StringList(envList("CGO_LDFLAGS", defaults), p.CgoLDFLAGS)
 	return
 }
 
@@ -3354,7 +3355,7 @@ func (b *builder) cgo(a *action, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofil
 	outGo = append(outGo, gofiles...)
 
 	// gcc
-	cflags := stringList(cgoCPPFLAGS, cgoCFLAGS)
+	cflags := str.StringList(cgoCPPFLAGS, cgoCFLAGS)
 	for _, cfile := range cfiles {
 		ofile := obj + cfile[:len(cfile)-1] + "o"
 		if err := b.gcc(p, ofile, cflags, obj+cfile); err != nil {
@@ -3372,7 +3373,7 @@ func (b *builder) cgo(a *action, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofil
 		outObj = append(outObj, ofile)
 	}
 
-	cxxflags := stringList(cgoCPPFLAGS, cgoCXXFLAGS)
+	cxxflags := str.StringList(cgoCPPFLAGS, cgoCXXFLAGS)
 	for _, file := range gxxfiles {
 		// Append .o to the file, just in case the pkg has file.c and file.cpp
 		ofile := obj + cgoRe.ReplaceAllString(filepath.Base(file), "_") + ".o"
@@ -3391,7 +3392,7 @@ func (b *builder) cgo(a *action, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofil
 		outObj = append(outObj, ofile)
 	}
 
-	fflags := stringList(cgoCPPFLAGS, cgoFFLAGS)
+	fflags := str.StringList(cgoCPPFLAGS, cgoFFLAGS)
 	for _, file := range ffiles {
 		// Append .o to the file, just in case the pkg has file.c and file.f
 		ofile := obj + cgoRe.ReplaceAllString(filepath.Base(file), "_") + ".o"
@@ -3440,7 +3441,7 @@ func (b *builder) dynimport(p *Package, obj, importGo, cgoExe string, cflags, cg
 		return err
 	}
 
-	linkobj := stringList(ofile, outObj, p.SysoFiles)
+	linkobj := str.StringList(ofile, outObj, p.SysoFiles)
 	dynobj := obj + "_cgo_.o"
 
 	// we need to use -pie for Linux/ARM to get accurate imported sym
@@ -3672,9 +3673,9 @@ func (b *builder) swigOne(p *Package, file, obj string, pcCFLAGS []string, cxx b
 	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, _, _ := b.cflags(p)
 	var cflags []string
 	if cxx {
-		cflags = stringList(cgoCPPFLAGS, pcCFLAGS, cgoCXXFLAGS)
+		cflags = str.StringList(cgoCPPFLAGS, pcCFLAGS, cgoCXXFLAGS)
 	} else {
-		cflags = stringList(cgoCPPFLAGS, pcCFLAGS, cgoCFLAGS)
+		cflags = str.StringList(cgoCPPFLAGS, pcCFLAGS, cgoCFLAGS)
 	}
 
 	n := 5 // length of ".swig"
diff --git a/src/cmd/go/fix.go b/src/cmd/go/fix.go
index 3af7adb4e1..01d5bbcc38 100644
--- a/src/cmd/go/fix.go
+++ b/src/cmd/go/fix.go
@@ -4,6 +4,8 @@
 
 package main
 
+import "cmd/go/internal/str"
+
 var cmdFix = &Command{
 	Run:       runFix,
 	UsageLine: "fix [packages]",
@@ -25,6 +27,6 @@ func runFix(cmd *Command, args []string) {
 		// Use pkg.gofiles instead of pkg.Dir so that
 		// the command only applies to this package,
 		// not to packages in subdirectories.
-		run(stringList(buildToolExec, tool("fix"), relPaths(pkg.allgofiles)))
+		run(str.StringList(buildToolExec, tool("fix"), relPaths(pkg.allgofiles)))
 	}
 }
diff --git a/src/cmd/go/fmt.go b/src/cmd/go/fmt.go
index 4ed7722575..4c40f9ab0b 100644
--- a/src/cmd/go/fmt.go
+++ b/src/cmd/go/fmt.go
@@ -5,6 +5,7 @@
 package main
 
 import (
+	"cmd/go/internal/str"
 	"os"
 	"path/filepath"
 )
@@ -39,7 +40,7 @@ func runFmt(cmd *Command, args []string) {
 		// Use pkg.gofiles instead of pkg.Dir so that
 		// the command only applies to this package,
 		// not to packages in subdirectories.
-		run(stringList(gofmt, "-l", "-w", relPaths(pkg.allgofiles)))
+		run(str.StringList(gofmt, "-l", "-w", relPaths(pkg.allgofiles)))
 	}
 }
 
diff --git a/src/cmd/go/get.go b/src/cmd/go/get.go
index 1d7677c615..c433cff812 100644
--- a/src/cmd/go/get.go
+++ b/src/cmd/go/get.go
@@ -5,6 +5,7 @@
 package main
 
 import (
+	"cmd/go/internal/str"
 	"fmt"
 	"go/build"
 	"os"
@@ -302,7 +303,7 @@ func download(arg string, parent *Package, stk *importStack, mode int) {
 	// due to wildcard expansion.
 	for _, p := range pkgs {
 		if *getFix {
-			run(buildToolExec, stringList(tool("fix"), relPaths(p.allgofiles)))
+			run(buildToolExec, str.StringList(tool("fix"), relPaths(p.allgofiles)))
 
 			// The imports might have changed, so reload again.
 			p = reloadPackage(arg, stk)
@@ -324,7 +325,7 @@ func download(arg string, parent *Package, stk *importStack, mode int) {
 			// Process test dependencies when -t is specified.
 			// (But don't get test dependencies for test dependencies:
 			// we always pass mode 0 to the recursive calls below.)
-			imports = stringList(imports, p.TestImports, p.XTestImports)
+			imports = str.StringList(imports, p.TestImports, p.XTestImports)
 		}
 		for i, path := range imports {
 			if path == "C" {
diff --git a/src/cmd/go/internal/str/str.go b/src/cmd/go/internal/str/str.go
new file mode 100644
index 0000000000..d3583b48e4
--- /dev/null
+++ b/src/cmd/go/internal/str/str.go
@@ -0,0 +1,97 @@
+// 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 str provides string manipulation utilities.
+package str
+
+import (
+	"bytes"
+	"fmt"
+	"unicode"
+	"unicode/utf8"
+)
+
+// StringList flattens its arguments into a single []string.
+// Each argument in args must have type string or []string.
+func StringList(args ...interface{}) []string {
+	var x []string
+	for _, arg := range args {
+		switch arg := arg.(type) {
+		case []string:
+			x = append(x, arg...)
+		case string:
+			x = append(x, arg)
+		default:
+			panic("stringList: invalid argument of type " + fmt.Sprintf("%T", arg))
+		}
+	}
+	return x
+}
+
+// toFold returns a string with the property that
+//	strings.EqualFold(s, t) iff toFold(s) == toFold(t)
+// This lets us test a large set of strings for fold-equivalent
+// duplicates without making a quadratic number of calls
+// to EqualFold. Note that strings.ToUpper and strings.ToLower
+// do not have the desired property in some corner cases.
+func toFold(s string) string {
+	// Fast path: all ASCII, no upper case.
+	// Most paths look like this already.
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if c >= utf8.RuneSelf || 'A' <= c && c <= 'Z' {
+			goto Slow
+		}
+	}
+	return s
+
+Slow:
+	var buf bytes.Buffer
+	for _, r := range s {
+		// SimpleFold(x) cycles to the next equivalent rune > x
+		// or wraps around to smaller values. Iterate until it wraps,
+		// and we've found the minimum value.
+		for {
+			r0 := r
+			r = unicode.SimpleFold(r0)
+			if r <= r0 {
+				break
+			}
+		}
+		// Exception to allow fast path above: A-Z => a-z
+		if 'A' <= r && r <= 'Z' {
+			r += 'a' - 'A'
+		}
+		buf.WriteRune(r)
+	}
+	return buf.String()
+}
+
+// FoldDup reports a pair of strings from the list that are
+// equal according to strings.EqualFold.
+// It returns "", "" if there are no such strings.
+func FoldDup(list []string) (string, string) {
+	clash := map[string]string{}
+	for _, s := range list {
+		fold := toFold(s)
+		if t := clash[fold]; t != "" {
+			if s > t {
+				s, t = t, s
+			}
+			return s, t
+		}
+		clash[fold] = s
+	}
+	return "", ""
+}
+
+// Contains reports whether x contains s.
+func Contains(x []string, s string) bool {
+	for _, t := range x {
+		if t == s {
+			return true
+		}
+	}
+	return false
+}
diff --git a/src/cmd/go/main.go b/src/cmd/go/main.go
index dfd0e9aa1f..abccc6e0fa 100644
--- a/src/cmd/go/main.go
+++ b/src/cmd/go/main.go
@@ -7,6 +7,7 @@ package main
 import (
 	"bufio"
 	"bytes"
+	"cmd/go/internal/str"
 	"flag"
 	"fmt"
 	"go/build"
@@ -453,7 +454,7 @@ func exitIfErrors() {
 }
 
 func run(cmdargs ...interface{}) {
-	cmdline := stringList(cmdargs...)
+	cmdline := str.StringList(cmdargs...)
 	if buildN || buildX {
 		fmt.Printf("%s\n", strings.Join(cmdline, " "))
 		if buildN {
@@ -730,77 +731,3 @@ func matchPackagesInFS(pattern string) []string {
 	})
 	return pkgs
 }
-
-// stringList's arguments should be a sequence of string or []string values.
-// stringList flattens them into a single []string.
-func stringList(args ...interface{}) []string {
-	var x []string
-	for _, arg := range args {
-		switch arg := arg.(type) {
-		case []string:
-			x = append(x, arg...)
-		case string:
-			x = append(x, arg)
-		default:
-			panic("stringList: invalid argument of type " + fmt.Sprintf("%T", arg))
-		}
-	}
-	return x
-}
-
-// toFold returns a string with the property that
-//	strings.EqualFold(s, t) iff toFold(s) == toFold(t)
-// This lets us test a large set of strings for fold-equivalent
-// duplicates without making a quadratic number of calls
-// to EqualFold. Note that strings.ToUpper and strings.ToLower
-// have the desired property in some corner cases.
-func toFold(s string) string {
-	// Fast path: all ASCII, no upper case.
-	// Most paths look like this already.
-	for i := 0; i < len(s); i++ {
-		c := s[i]
-		if c >= utf8.RuneSelf || 'A' <= c && c <= 'Z' {
-			goto Slow
-		}
-	}
-	return s
-
-Slow:
-	var buf bytes.Buffer
-	for _, r := range s {
-		// SimpleFold(x) cycles to the next equivalent rune > x
-		// or wraps around to smaller values. Iterate until it wraps,
-		// and we've found the minimum value.
-		for {
-			r0 := r
-			r = unicode.SimpleFold(r0)
-			if r <= r0 {
-				break
-			}
-		}
-		// Exception to allow fast path above: A-Z => a-z
-		if 'A' <= r && r <= 'Z' {
-			r += 'a' - 'A'
-		}
-		buf.WriteRune(r)
-	}
-	return buf.String()
-}
-
-// foldDup reports a pair of strings from the list that are
-// equal according to strings.EqualFold.
-// It returns "", "" if there are no such strings.
-func foldDup(list []string) (string, string) {
-	clash := map[string]string{}
-	for _, s := range list {
-		fold := toFold(s)
-		if t := clash[fold]; t != "" {
-			if s > t {
-				s, t = t, s
-			}
-			return s, t
-		}
-		clash[fold] = s
-	}
-	return "", ""
-}
diff --git a/src/cmd/go/pkg.go b/src/cmd/go/pkg.go
index 8fb6bddde1..032687e405 100644
--- a/src/cmd/go/pkg.go
+++ b/src/cmd/go/pkg.go
@@ -6,6 +6,7 @@ package main
 
 import (
 	"bytes"
+	"cmd/go/internal/str"
 	"crypto/sha1"
 	"errors"
 	"fmt"
@@ -971,19 +972,19 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 
 	// Build list of full paths to all Go files in the package,
 	// for use by commands like go fmt.
-	p.gofiles = stringList(p.GoFiles, p.CgoFiles, p.TestGoFiles, p.XTestGoFiles)
+	p.gofiles = str.StringList(p.GoFiles, p.CgoFiles, p.TestGoFiles, p.XTestGoFiles)
 	for i := range p.gofiles {
 		p.gofiles[i] = filepath.Join(p.Dir, p.gofiles[i])
 	}
 	sort.Strings(p.gofiles)
 
-	p.sfiles = stringList(p.SFiles)
+	p.sfiles = str.StringList(p.SFiles)
 	for i := range p.sfiles {
 		p.sfiles[i] = filepath.Join(p.Dir, p.sfiles[i])
 	}
 	sort.Strings(p.sfiles)
 
-	p.allgofiles = stringList(p.IgnoredGoFiles)
+	p.allgofiles = str.StringList(p.IgnoredGoFiles)
 	for i := range p.allgofiles {
 		p.allgofiles[i] = filepath.Join(p.Dir, p.allgofiles[i])
 	}
@@ -994,7 +995,7 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 	// To avoid problems on case-insensitive files, we reject any package
 	// where two different input files have equal names under a case-insensitive
 	// comparison.
-	f1, f2 := foldDup(stringList(
+	f1, f2 := str.FoldDup(str.StringList(
 		p.GoFiles,
 		p.CgoFiles,
 		p.IgnoredGoFiles,
@@ -1112,7 +1113,7 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 	// In the absence of errors lower in the dependency tree,
 	// check for case-insensitive collisions of import paths.
 	if len(p.DepsErrors) == 0 {
-		dep1, dep2 := foldDup(p.Deps)
+		dep1, dep2 := str.FoldDup(p.Deps)
 		if dep1 != "" {
 			p.Error = &PackageError{
 				ImportStack: stk.copy(),
@@ -1605,7 +1606,7 @@ func isStale(p *Package) (bool, string) {
 	// to test for write access, and then skip GOPATH roots we don't have write
 	// access to. But hopefully we can just use the mtimes always.
 
-	srcs := stringList(p.GoFiles, p.CFiles, p.CXXFiles, p.MFiles, p.HFiles, p.FFiles, p.SFiles, p.CgoFiles, p.SysoFiles, p.SwigFiles, p.SwigCXXFiles)
+	srcs := str.StringList(p.GoFiles, p.CFiles, p.CXXFiles, p.MFiles, p.HFiles, p.FFiles, p.SFiles, p.CgoFiles, p.SysoFiles, p.SwigFiles, p.SwigCXXFiles)
 	for _, src := range srcs {
 		if olderThan(filepath.Join(p.Dir, src)) {
 			return true, "newer source file"
@@ -1623,7 +1624,7 @@ func computeBuildID(p *Package) {
 
 	// Include the list of files compiled as part of the package.
 	// This lets us detect removed files. See issue 3895.
-	inputFiles := stringList(
+	inputFiles := str.StringList(
 		p.GoFiles,
 		p.CgoFiles,
 		p.CFiles,
diff --git a/src/cmd/go/pkg_test.go b/src/cmd/go/pkg_test.go
index fba13636cd..f822df8b6b 100644
--- a/src/cmd/go/pkg_test.go
+++ b/src/cmd/go/pkg_test.go
@@ -5,6 +5,7 @@
 package main
 
 import (
+	"cmd/go/internal/str"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -17,16 +18,16 @@ var foldDupTests = []struct {
 	list   []string
 	f1, f2 string
 }{
-	{stringList("math/rand", "math/big"), "", ""},
-	{stringList("math", "strings"), "", ""},
-	{stringList("strings"), "", ""},
-	{stringList("strings", "strings"), "strings", "strings"},
-	{stringList("Rand", "rand", "math", "math/rand", "math/Rand"), "Rand", "rand"},
+	{str.StringList("math/rand", "math/big"), "", ""},
+	{str.StringList("math", "strings"), "", ""},
+	{str.StringList("strings"), "", ""},
+	{str.StringList("strings", "strings"), "strings", "strings"},
+	{str.StringList("Rand", "rand", "math", "math/rand", "math/Rand"), "Rand", "rand"},
 }
 
 func TestFoldDup(t *testing.T) {
 	for _, tt := range foldDupTests {
-		f1, f2 := foldDup(tt.list)
+		f1, f2 := str.FoldDup(tt.list)
 		if f1 != tt.f1 || f2 != tt.f2 {
 			t.Errorf("foldDup(%q) = %q, %q, want %q, %q", tt.list, f1, f2, tt.f1, tt.f2)
 		}
diff --git a/src/cmd/go/run.go b/src/cmd/go/run.go
index 18387b5eaf..30d589777c 100644
--- a/src/cmd/go/run.go
+++ b/src/cmd/go/run.go
@@ -5,6 +5,7 @@
 package main
 
 import (
+	"cmd/go/internal/str"
 	"fmt"
 	"os"
 	"os/exec"
@@ -130,7 +131,7 @@ func runRun(cmd *Command, args []string) {
 // runProgram is the action for running a binary that has already
 // been compiled. We ignore exit status.
 func (b *builder) runProgram(a *action) error {
-	cmdline := stringList(findExecCmd(), a.deps[0].target, a.args)
+	cmdline := str.StringList(findExecCmd(), a.deps[0].target, a.args)
 	if buildN || buildX {
 		b.showcmd("", "%s", strings.Join(cmdline, " "))
 		if buildN {
diff --git a/src/cmd/go/test.go b/src/cmd/go/test.go
index 1445e9f395..ab0add32bb 100644
--- a/src/cmd/go/test.go
+++ b/src/cmd/go/test.go
@@ -6,6 +6,7 @@ package main
 
 import (
 	"bytes"
+	"cmd/go/internal/str"
 	"errors"
 	"fmt"
 	"go/ast"
@@ -636,15 +637,6 @@ func runTest(cmd *Command, args []string) {
 	b.do(root)
 }
 
-func contains(x []string, s string) bool {
-	for _, t := range x {
-		if t == s {
-			return true
-		}
-	}
-	return false
-}
-
 var windowsBadWords = []string{
 	"install",
 	"patch",
@@ -679,7 +671,7 @@ func builderTest(b *builder, p *Package) (buildAction, runAction, printAction *a
 			err.Pos = "" // show full import stack
 			return nil, nil, nil, err
 		}
-		if contains(p1.Deps, p.ImportPath) || p1.ImportPath == p.ImportPath {
+		if str.Contains(p1.Deps, p.ImportPath) || p1.ImportPath == p.ImportPath {
 			// Same error that loadPackage returns (via reusePackage) in pkg.go.
 			// Can't change that code, because that code is only for loading the
 			// non-test copy of a package.
@@ -764,7 +756,7 @@ func builderTest(b *builder, p *Package) (buildAction, runAction, printAction *a
 		ptest.GoFiles = append(ptest.GoFiles, p.GoFiles...)
 		ptest.GoFiles = append(ptest.GoFiles, p.TestGoFiles...)
 		ptest.target = ""
-		ptest.Imports = stringList(p.Imports, p.TestImports)
+		ptest.Imports = str.StringList(p.Imports, p.TestImports)
 		ptest.imports = append(append([]*Package{}, p.imports...), imports...)
 		ptest.pkgdir = testDir
 		ptest.fake = true
@@ -1016,7 +1008,7 @@ func testImportStack(top string, p *Package, target string) []string {
 Search:
 	for p.ImportPath != target {
 		for _, p1 := range p.imports {
-			if p1.ImportPath == target || contains(p1.Deps, target) {
+			if p1.ImportPath == target || str.Contains(p1.Deps, target) {
 				stk = append(stk, p1.ImportPath)
 				p = p1
 				continue Search
@@ -1103,7 +1095,7 @@ var noTestsToRun = []byte("\ntesting: warning: no tests to run\n")
 
 // builderRunTest is the action for running a test binary.
 func builderRunTest(b *builder, a *action) error {
-	args := stringList(findExecCmd(), a.deps[0].target, testArgs)
+	args := str.StringList(findExecCmd(), a.deps[0].target, testArgs)
 	a.testOutput = new(bytes.Buffer)
 
 	if buildN || buildX {
diff --git a/src/cmd/go/vet.go b/src/cmd/go/vet.go
index 8e296c8572..2e2d9e1de2 100644
--- a/src/cmd/go/vet.go
+++ b/src/cmd/go/vet.go
@@ -4,7 +4,11 @@
 
 package main
 
-import "path/filepath"
+import (
+	"path/filepath"
+
+	"cmd/go/internal/str"
+)
 
 func init() {
 	addBuildFlags(cmdVet)
@@ -36,10 +40,10 @@ func runVet(cmd *Command, args []string) {
 		// Vet expects to be given a set of files all from the same package.
 		// Run once for package p and once for package p_test.
 		if len(p.GoFiles)+len(p.CgoFiles)+len(p.TestGoFiles) > 0 {
-			runVetFiles(p, stringList(p.GoFiles, p.CgoFiles, p.TestGoFiles, p.SFiles))
+			runVetFiles(p, str.StringList(p.GoFiles, p.CgoFiles, p.TestGoFiles, p.SFiles))
 		}
 		if len(p.XTestGoFiles) > 0 {
-			runVetFiles(p, stringList(p.XTestGoFiles))
+			runVetFiles(p, str.StringList(p.XTestGoFiles))
 		}
 	}
 }
-- 
2.50.0