cmd: move internal/str back to cmd/go

cmd/go is not subject to all the same restrictions as most of cmd.
In particular it need not be buildable with the bootstrap toolchain.
So it is better to keep as little code shared between cmd/go and
cmd/compile, cmd/link, cmd/cgo as possible.

cmd/internal/str started as cmd/go/internal/str but was moved
to cmd/internal in order to make use of the quoted string code.
Move that code to cmd/internal/quoted and then move the rest of
cmd/internal/str back to cmd/go/internal/str.

Change-Id: I3a98f754d545cc3af7e9a32c2b77a5a035ea7b9a
Reviewed-on: https://go-review.googlesource.com/c/go/+/355010
Trust: Russ Cox <[email protected]>
Run-TryBot: Russ Cox <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Bryan C. Mills <[email protected]>

Author: rsc

src/cmd/cgo/gcc.go

@@ -29,7 +29,7 @@ import (
 	"unicode"
 	"unicode/utf8"
 
-	"cmd/internal/str"
+	"cmd/internal/quoted"
 )
 
 var debugDefine = flag.Bool("debug-define", false, "print relevant #defines")
@@ -1568,7 +1568,7 @@ func checkGCCBaseCmd() ([]string, error) {
 	if value == "" {
 		value = defaultCC(goos, goarch)
 	}
-	args, err := str.SplitQuotedFields(value)
+	args, err := quoted.Split(value)
 	if err != nil {
 		return nil, err
 	}

src/cmd/compile/internal/ssa/stmtlines_test.go

@@ -2,7 +2,7 @@ package ssa_test
 
 import (
 	cmddwarf "cmd/internal/dwarf"
-	"cmd/internal/str"
+	"cmd/internal/quoted"
 	"debug/dwarf"
 	"debug/elf"
 	"debug/macho"
@@ -58,7 +58,7 @@ func TestStmtLines(t *testing.T) {
 		if extld == "" {
 			extld = "gcc"
 		}
-		extldArgs, err := str.SplitQuotedFields(extld)
+		extldArgs, err := quoted.Split(extld)
 		if err != nil {
 			t.Fatal(err)
 		}

src/cmd/dist/buildtool.go

@@ -46,8 +46,8 @@ var bootstrapDirs = []string{
 	"cmd/internal/obj/...",
 	"cmd/internal/objabi",
 	"cmd/internal/pkgpath",
+	"cmd/internal/quoted",
 	"cmd/internal/src",
-	"cmd/internal/str",
 	"cmd/internal/sys",
 	"cmd/link",
 	"cmd/link/internal/...",

src/cmd/go/internal/base/base.go

@@ -17,7 +17,7 @@ import (
 	"sync"
 
 	"cmd/go/internal/cfg"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 )
 
 // A Command is an implementation of a go command

src/cmd/go/internal/base/flag.go

@@ -9,7 +9,7 @@ import (
 
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/fsys"
-	"cmd/internal/str"
+	"cmd/internal/quoted"
 )
 
 // A StringsFlag is a command-line flag that interprets its argument
@@ -18,7 +18,7 @@ type StringsFlag []string
 
 func (v *StringsFlag) Set(s string) error {
 	var err error
-	*v, err = str.SplitQuotedFields(s)
+	*v, err = quoted.Split(s)
 	if *v == nil {
 		*v = []string{}
 	}

src/cmd/go/internal/envcmd/env.go

@@ -26,7 +26,7 @@ import (
 	"cmd/go/internal/load"
 	"cmd/go/internal/modload"
 	"cmd/go/internal/work"
-	"cmd/internal/str"
+	"cmd/internal/quoted"
 )
 
 var CmdEnv = &base.Command{
@@ -470,7 +470,7 @@ func checkEnvWrite(key, val string) error {
 		if val == "" {
 			break
 		}
-		args, err := str.SplitQuotedFields(val)
+		args, err := quoted.Split(val)
 		if err != nil {
 			return fmt.Errorf("invalid %s: %v", key, err)
 		}

src/cmd/go/internal/fix/fix.go

@@ -10,7 +10,7 @@ import (
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/load"
 	"cmd/go/internal/modload"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 	"context"
 	"fmt"
 	"os"

src/cmd/go/internal/generate/generate.go

@@ -26,7 +26,7 @@ import (
 	"cmd/go/internal/load"
 	"cmd/go/internal/modload"
 	"cmd/go/internal/work"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 )
 
 var CmdGenerate = &base.Command{

src/cmd/go/internal/get/get.go

@@ -20,7 +20,7 @@ import (
 	"cmd/go/internal/vcs"
 	"cmd/go/internal/web"
 	"cmd/go/internal/work"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 
 	"golang.org/x/mod/module"
 )

src/cmd/go/internal/list/list.go

@@ -24,7 +24,7 @@ import (
 	"cmd/go/internal/modinfo"
 	"cmd/go/internal/modload"
 	"cmd/go/internal/work"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 )
 
 var CmdList = &base.Command{

src/cmd/go/internal/load/flag.go

@@ -6,7 +6,7 @@ package load
 
 import (
 	"cmd/go/internal/base"
-	"cmd/internal/str"
+	"cmd/internal/quoted"
 	"fmt"
 	"strings"
 )
@@ -63,7 +63,7 @@ func (f *PerPackageFlag) set(v, cwd string) error {
 		match = MatchPackage(pattern, cwd)
 		v = v[i+1:]
 	}
-	flags, err := str.SplitQuotedFields(v)
+	flags, err := quoted.Split(v)
 	if err != nil {
 		return err
 	}

src/cmd/go/internal/load/pkg.go

@@ -38,9 +38,9 @@ import (
 	"cmd/go/internal/modload"
 	"cmd/go/internal/par"
 	"cmd/go/internal/search"
+	"cmd/go/internal/str"
 	"cmd/go/internal/trace"
 	"cmd/go/internal/vcs"
-	"cmd/internal/str"
 	"cmd/internal/sys"
 
 	"golang.org/x/mod/modfile"

src/cmd/go/internal/load/test.go

@@ -23,7 +23,7 @@ import (
 
 	"cmd/go/internal/fsys"
 	"cmd/go/internal/trace"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 )
 
 var TestMainDeps = []string{

src/cmd/go/internal/modcmd/vendor.go

@@ -24,7 +24,7 @@ import (
 	"cmd/go/internal/imports"
 	"cmd/go/internal/load"
 	"cmd/go/internal/modload"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 
 	"golang.org/x/mod/module"
 	"golang.org/x/mod/semver"

src/cmd/go/internal/modfetch/codehost/codehost.go

@@ -21,7 +21,7 @@ import (
 
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/lockedfile"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 )
 
 // Downloaded size limits.

src/cmd/go/internal/modfetch/codehost/vcs.go

@@ -20,7 +20,7 @@ import (
 
 	"cmd/go/internal/lockedfile"
 	"cmd/go/internal/par"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 )
 
 // A VCSError indicates an error using a version control system.

src/cmd/go/internal/modget/query.go

@@ -14,7 +14,7 @@ import (
 	"cmd/go/internal/base"
 	"cmd/go/internal/modload"
 	"cmd/go/internal/search"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 
 	"golang.org/x/mod/module"
 )

src/cmd/go/internal/modload/load.go

@@ -119,7 +119,7 @@ import (
 	"cmd/go/internal/mvs"
 	"cmd/go/internal/par"
 	"cmd/go/internal/search"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 
 	"golang.org/x/mod/module"
 	"golang.org/x/mod/semver"

src/cmd/go/internal/modload/query.go

@@ -22,7 +22,7 @@ import (
 	"cmd/go/internal/modfetch"
 	"cmd/go/internal/search"
 	"cmd/go/internal/trace"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 
 	"golang.org/x/mod/module"
 	"golang.org/x/mod/semver"

src/cmd/go/internal/run/run.go

@@ -19,7 +19,7 @@ import (
 	"cmd/go/internal/load"
 	"cmd/go/internal/modload"
 	"cmd/go/internal/work"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 )
 
 var CmdRun = &base.Command{

src/cmd/internal/str/path.go renamed to src/cmd/go/internal/str/path.go

@@ -0,0 +1,111 @@
+// 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
+}
+
+// Uniq removes consecutive duplicate strings from ss.
+func Uniq(ss *[]string) {
+	if len(*ss) <= 1 {
+		return
+	}
+	uniq := (*ss)[:1]
+	for _, s := range *ss {
+		if s != uniq[len(uniq)-1] {
+			uniq = append(uniq, s)
+		}
+	}
+	*ss = uniq
+}

src/cmd/go/internal/str/str.go

@@ -0,0 +1,29 @@
+// Copyright 2020 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
+
+import (
+	"testing"
+)
+
+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"},
+}
+
+func TestFoldDup(t *testing.T) {
+	for _, tt := range foldDupTests {
+		f1, f2 := 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)
+		}
+	}
+}

src/cmd/go/internal/str/str_test.go

@@ -33,7 +33,7 @@ import (
 	"cmd/go/internal/search"
 	"cmd/go/internal/trace"
 	"cmd/go/internal/work"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 	"cmd/internal/test2json"
 )
 

src/cmd/go/internal/test/test.go

@@ -27,7 +27,7 @@ import (
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/search"
 	"cmd/go/internal/web"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 
 	"golang.org/x/mod/module"
 )

src/cmd/go/internal/vcs/vcs.go

@@ -16,7 +16,7 @@ import (
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/fsys"
 	"cmd/internal/buildid"
-	"cmd/internal/str"
+	"cmd/go/internal/str"
 )
 
 // Build IDs