src/cmd/dist/buildtool.go - go - Git at Google

 // 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.

 // Build toolchain using Go 1.4.
 //
 // The general strategy is to copy the source files we need into
 // a new GOPATH workspace, adjust import paths appropriately,
 // invoke the Go 1.4 go command to build those sources,
 // and then copy the binaries back.

 package main

 import (
 	"fmt"
 	"os"
 	"path/filepath"
 	"runtime"
 	"strings"
 )

 // bootstrapDirs is a list of directories holding code that must be
 // compiled with a Go 1.4 toolchain to produce the bootstrapTargets.
 // All directories in this list are relative to and must be below $GOROOT/src.
 //
 // The list has have two kinds of entries: names beginning with cmd/ with
 // no other slashes, which are commands, and other paths, which are packages
 // supporting the commands. Packages in the standard library can be listed
 // if a newer copy needs to be substituted for the Go 1.4 copy when used
 // by the command packages.
 // These will be imported during bootstrap as bootstrap/name, like bootstrap/math/big.
 var bootstrapDirs = []string{
 	"cmd/asm",
 	"cmd/asm/internal/arch",
 	"cmd/asm/internal/asm",
 	"cmd/asm/internal/flags",
 	"cmd/asm/internal/lex",
 	"cmd/cgo",
 	"cmd/compile",
 	"cmd/compile/internal/amd64",
 	"cmd/compile/internal/arm",
 	"cmd/compile/internal/arm64",
 	"cmd/compile/internal/gc",
 	"cmd/compile/internal/logopt",
 	"cmd/compile/internal/mips",
 	"cmd/compile/internal/mips64",
 	"cmd/compile/internal/ppc64",
 	"cmd/compile/internal/riscv64",
 	"cmd/compile/internal/s390x",
 	"cmd/compile/internal/ssa",
 	"cmd/compile/internal/syntax",
 	"cmd/compile/internal/types",
 	"cmd/compile/internal/x86",
 	"cmd/compile/internal/wasm",
 	"cmd/internal/bio",
 	"cmd/internal/gcprog",
 	"cmd/internal/dwarf",
 	"cmd/internal/edit",
 	"cmd/internal/goobj",
 	"cmd/internal/objabi",
 	"cmd/internal/obj",
 	"cmd/internal/obj/arm",
 	"cmd/internal/obj/arm64",
 	"cmd/internal/obj/mips",
 	"cmd/internal/obj/ppc64",
 	"cmd/internal/obj/riscv",
 	"cmd/internal/obj/s390x",
 	"cmd/internal/obj/x86",
 	"cmd/internal/obj/wasm",
 	"cmd/internal/src",
 	"cmd/internal/sys",
 	"cmd/link",
 	"cmd/link/internal/amd64",
 	"cmd/link/internal/arm",
 	"cmd/link/internal/arm64",
 	"cmd/link/internal/benchmark",
 	"cmd/link/internal/ld",
 	"cmd/link/internal/loadelf",
 	"cmd/link/internal/loader",
 	"cmd/link/internal/loadmacho",
 	"cmd/link/internal/loadpe",
 	"cmd/link/internal/loadxcoff",
 	"cmd/link/internal/mips",
 	"cmd/link/internal/mips64",
 	"cmd/link/internal/ppc64",
 	"cmd/link/internal/riscv64",
 	"cmd/link/internal/s390x",
 	"cmd/link/internal/sym",
 	"cmd/link/internal/x86",
 	"compress/flate",
 	"compress/zlib",
 	"cmd/link/internal/wasm",
 	"container/heap",
 	"debug/dwarf",
 	"debug/elf",
 	"debug/macho",
 	"debug/pe",
 	"internal/goversion",
 	"internal/race",
 	"internal/unsafeheader",
 	"internal/xcoff",
 	"math/big",
 	"math/bits",
 	"sort",
 }

 // File prefixes that are ignored by go/build anyway, and cause
 // problems with editor generated temporary files (#18931).
 var ignorePrefixes = []string{
 	".",
 	"_",
 }

 // File suffixes that use build tags introduced since Go 1.4.
 // These must not be copied into the bootstrap build directory.
 // Also ignore test files.
 var ignoreSuffixes = []string{
 	"_arm64.s",
 	"_arm64.go",
 	"_riscv64.s",
 	"_riscv64.go",
 	"_wasm.s",
 	"_wasm.go",
 	"_test.s",
 }

 func bootstrapBuildTools() {
 	goroot_bootstrap := os.Getenv("GOROOT_BOOTSTRAP")
 	if goroot_bootstrap == "" {
 		goroot_bootstrap = pathf("%s/go1.4", os.Getenv("HOME"))
 	}
 	xprintf("Building Go toolchain1 using %s.\n", goroot_bootstrap)

 	mkzbootstrap(pathf("%s/src/cmd/internal/objabi/zbootstrap.go", goroot))

 	// Use $GOROOT/pkg/bootstrap as the bootstrap workspace root.
 	// We use a subdirectory of $GOROOT/pkg because that's the
 	// space within $GOROOT where we store all generated objects.
 	// We could use a temporary directory outside $GOROOT instead,
 	// but it is easier to debug on failure if the files are in a known location.
 	workspace := pathf("%s/pkg/bootstrap", goroot)
 	xremoveall(workspace)
 	xatexit(func() { xremoveall(workspace) })
 	base := pathf("%s/src/bootstrap", workspace)
 	xmkdirall(base)

 	// Copy source code into $GOROOT/pkg/bootstrap and rewrite import paths.
 	writefile("module bootstrap\n", pathf("%s/%s", base, "go.mod"), 0)
 	for _, dir := range bootstrapDirs {
 		src := pathf("%s/src/%s", goroot, dir)
 		dst := pathf("%s/%s", base, dir)
 		xmkdirall(dst)
 		if dir == "cmd/cgo" {
 			// Write to src because we need the file both for bootstrap
 			// and for later in the main build.
 			mkzdefaultcc("", pathf("%s/zdefaultcc.go", src))
 		}
 	Dir:
 		for _, name := range xreaddirfiles(src) {
 			for _, pre := range ignorePrefixes {
 				if strings.HasPrefix(name, pre) {
 					continue Dir
 				}
 			}
 			for _, suf := range ignoreSuffixes {
 				if strings.HasSuffix(name, suf) {
 					continue Dir
 				}
 			}
 			srcFile := pathf("%s/%s", src, name)
 			dstFile := pathf("%s/%s", dst, name)
 			text := bootstrapRewriteFile(srcFile)
 			writefile(text, dstFile, 0)
 		}
 	}

 	// Set up environment for invoking Go 1.4 go command.
 	// GOROOT points at Go 1.4 GOROOT,
 	// GOPATH points at our bootstrap workspace,
 	// GOBIN is empty, so that binaries are installed to GOPATH/bin,
 	// and GOOS, GOHOSTOS, GOARCH, and GOHOSTOS are empty,
 	// so that Go 1.4 builds whatever kind of binary it knows how to build.
 	// Restore GOROOT, GOPATH, and GOBIN when done.
 	// Don't bother with GOOS, GOHOSTOS, GOARCH, and GOHOSTARCH,
 	// because setup will take care of those when bootstrapBuildTools returns.

 	defer os.Setenv("GOROOT", os.Getenv("GOROOT"))
 	os.Setenv("GOROOT", goroot_bootstrap)

 	defer os.Setenv("GOPATH", os.Getenv("GOPATH"))
 	os.Setenv("GOPATH", workspace)

 	defer os.Setenv("GOBIN", os.Getenv("GOBIN"))
 	os.Setenv("GOBIN", "")

 	os.Setenv("GOOS", "")
 	os.Setenv("GOHOSTOS", "")
 	os.Setenv("GOARCH", "")
 	os.Setenv("GOHOSTARCH", "")

 	// Run Go 1.4 to build binaries. Use -gcflags=-l to disable inlining to
 	// workaround bugs in Go 1.4's compiler. See discussion thread:
 	// https://groups.google.com/d/msg/golang-dev/Ss7mCKsvk8w/Gsq7VYI0AwAJ
 	// Use the math_big_pure_go build tag to disable the assembly in math/big
 	// which may contain unsupported instructions.
 	// Note that if we are using Go 1.10 or later as bootstrap, the -gcflags=-l
 	// only applies to the final cmd/go binary, but that's OK: if this is Go 1.10
 	// or later we don't need to disable inlining to work around bugs in the Go 1.4 compiler.
 	cmd := []string{
 		pathf("%s/bin/go", goroot_bootstrap),
 		"install",
 		"-gcflags=-l",
 		"-tags=math_big_pure_go compiler_bootstrap",
 	}
 	if vflag > 0 {
 		cmd = append(cmd, "-v")
 	}
 	if tool := os.Getenv("GOBOOTSTRAP_TOOLEXEC"); tool != "" {
 		cmd = append(cmd, "-toolexec="+tool)
 	}
 	cmd = append(cmd, "bootstrap/cmd/...")
 	run(base, ShowOutput|CheckExit, cmd...)

 	// Copy binaries into tool binary directory.
 	for _, name := range bootstrapDirs {
 		if !strings.HasPrefix(name, "cmd/") {
 			continue
 		}
 		name = name[len("cmd/"):]
 		if !strings.Contains(name, "/") {
 			copyfile(pathf("%s/%s%s", tooldir, name, exe), pathf("%s/bin/%s%s", workspace, name, exe), writeExec)
 		}
 	}

 	if vflag > 0 {
 		xprintf("\n")
 	}
 }

 var ssaRewriteFileSubstring = filepath.FromSlash("src/cmd/compile/internal/ssa/rewrite")

 // isUnneededSSARewriteFile reports whether srcFile is a
 // src/cmd/compile/internal/ssa/rewriteARCHNAME.go file for an
 // architecture that isn't for the current runtime.GOARCH.
 //
 // When unneeded is true archCaps is the rewrite base filename without
 // the "rewrite" prefix or ".go" suffix: AMD64, 386, ARM, ARM64, etc.
 func isUnneededSSARewriteFile(srcFile string) (archCaps string, unneeded bool) {
 	if !strings.Contains(srcFile, ssaRewriteFileSubstring) {
 		return "", false
 	}
 	fileArch := strings.TrimSuffix(strings.TrimPrefix(filepath.Base(srcFile), "rewrite"), ".go")
 	if fileArch == "" {
 		return "", false
 	}
 	b := fileArch[0]
 	if b == '_' || ('a' <= b && b <= 'z') {
 		return "", false
 	}
 	archCaps = fileArch
 	fileArch = strings.ToLower(fileArch)
 	fileArch = strings.TrimSuffix(fileArch, "splitload")
 	if fileArch == os.Getenv("GOHOSTARCH") {
 		return "", false
 	}
 	if fileArch == strings.TrimSuffix(runtime.GOARCH, "le") {
 		return "", false
 	}
 	if fileArch == strings.TrimSuffix(os.Getenv("GOARCH"), "le") {
 		return "", false
 	}
 	return archCaps, true
 }

 func bootstrapRewriteFile(srcFile string) string {
 	// During bootstrap, generate dummy rewrite files for
 	// irrelevant architectures. We only need to build a bootstrap
 	// binary that works for the current runtime.GOARCH.
 	// This saves 6+ seconds of bootstrap.
 	if archCaps, ok := isUnneededSSARewriteFile(srcFile); ok {
 		return fmt.Sprintf(`// Code generated by go tool dist; DO NOT EDIT.

 package ssa

 func rewriteValue%s(v *Value) bool { panic("unused during bootstrap") }
 func rewriteBlock%s(b *Block) bool { panic("unused during bootstrap") }
 `, archCaps, archCaps)
 	}

 	return bootstrapFixImports(srcFile)
 }

 func bootstrapFixImports(srcFile string) string {
 	lines := strings.SplitAfter(readfile(srcFile), "\n")
 	inBlock := false
 	for i, line := range lines {
 		if strings.HasPrefix(line, "import (") {
 			inBlock = true
 			continue
 		}
 		if inBlock && strings.HasPrefix(line, ")") {
 			inBlock = false
 			continue
 		}
 		if strings.HasPrefix(line, `import "`) || strings.HasPrefix(line, `import . "`) ||
 			inBlock && (strings.HasPrefix(line, "\t\"") || strings.HasPrefix(line, "\t. \"")) {
 			line = strings.Replace(line, `"cmd/`, `"bootstrap/cmd/`, -1)
 			for _, dir := range bootstrapDirs {
 				if strings.HasPrefix(dir, "cmd/") {
 					continue
 				}
 				line = strings.Replace(line, `"`+dir+`"`, `"bootstrap/`+dir+`"`, -1)
 			}
 			lines[i] = line
 		}
 	}

 	lines[0] = "// Code generated by go tool dist; DO NOT EDIT.\n// This is a bootstrap copy of " + srcFile + "\n\n//line " + srcFile + ":1\n" + lines[0]

 	return strings.Join(lines, "")
 }
	// 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.

	// Build toolchain using Go 1.4.
	//
	// The general strategy is to copy the source files we need into
	// a new GOPATH workspace, adjust import paths appropriately,
	// invoke the Go 1.4 go command to build those sources,
	// and then copy the binaries back.

	package main

	import (
	"fmt"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	)

	// bootstrapDirs is a list of directories holding code that must be
	// compiled with a Go 1.4 toolchain to produce the bootstrapTargets.
	// All directories in this list are relative to and must be below $GOROOT/src.
	//
	// The list has have two kinds of entries: names beginning with cmd/ with
	// no other slashes, which are commands, and other paths, which are packages
	// supporting the commands. Packages in the standard library can be listed
	// if a newer copy needs to be substituted for the Go 1.4 copy when used
	// by the command packages.
	// These will be imported during bootstrap as bootstrap/name, like bootstrap/math/big.
	var bootstrapDirs = []string{
	"cmd/asm",
	"cmd/asm/internal/arch",
	"cmd/asm/internal/asm",
	"cmd/asm/internal/flags",
	"cmd/asm/internal/lex",
	"cmd/cgo",
	"cmd/compile",
	"cmd/compile/internal/amd64",
	"cmd/compile/internal/arm",
	"cmd/compile/internal/arm64",
	"cmd/compile/internal/gc",
	"cmd/compile/internal/logopt",
	"cmd/compile/internal/mips",
	"cmd/compile/internal/mips64",
	"cmd/compile/internal/ppc64",
	"cmd/compile/internal/riscv64",
	"cmd/compile/internal/s390x",
	"cmd/compile/internal/ssa",
	"cmd/compile/internal/syntax",
	"cmd/compile/internal/types",
	"cmd/compile/internal/x86",
	"cmd/compile/internal/wasm",
	"cmd/internal/bio",
	"cmd/internal/gcprog",
	"cmd/internal/dwarf",
	"cmd/internal/edit",
	"cmd/internal/goobj",
	"cmd/internal/objabi",
	"cmd/internal/obj",
	"cmd/internal/obj/arm",
	"cmd/internal/obj/arm64",
	"cmd/internal/obj/mips",
	"cmd/internal/obj/ppc64",
	"cmd/internal/obj/riscv",
	"cmd/internal/obj/s390x",
	"cmd/internal/obj/x86",
	"cmd/internal/obj/wasm",
	"cmd/internal/src",
	"cmd/internal/sys",
	"cmd/link",
	"cmd/link/internal/amd64",
	"cmd/link/internal/arm",
	"cmd/link/internal/arm64",
	"cmd/link/internal/benchmark",
	"cmd/link/internal/ld",
	"cmd/link/internal/loadelf",
	"cmd/link/internal/loader",
	"cmd/link/internal/loadmacho",
	"cmd/link/internal/loadpe",
	"cmd/link/internal/loadxcoff",
	"cmd/link/internal/mips",
	"cmd/link/internal/mips64",
	"cmd/link/internal/ppc64",
	"cmd/link/internal/riscv64",
	"cmd/link/internal/s390x",
	"cmd/link/internal/sym",
	"cmd/link/internal/x86",
	"compress/flate",
	"compress/zlib",
	"cmd/link/internal/wasm",
	"container/heap",
	"debug/dwarf",
	"debug/elf",
	"debug/macho",
	"debug/pe",
	"internal/goversion",
	"internal/race",
	"internal/unsafeheader",
	"internal/xcoff",
	"math/big",
	"math/bits",
	"sort",
	}

	// File prefixes that are ignored by go/build anyway, and cause
	// problems with editor generated temporary files (#18931).
	var ignorePrefixes = []string{
	".",
	"_",
	}

	// File suffixes that use build tags introduced since Go 1.4.
	// These must not be copied into the bootstrap build directory.
	// Also ignore test files.
	var ignoreSuffixes = []string{
	"_arm64.s",
	"_arm64.go",
	"_riscv64.s",
	"_riscv64.go",
	"_wasm.s",
	"_wasm.go",
	"_test.s",
	}

	func bootstrapBuildTools() {
	goroot_bootstrap := os.Getenv("GOROOT_BOOTSTRAP")
	if goroot_bootstrap == "" {
	goroot_bootstrap = pathf("%s/go1.4", os.Getenv("HOME"))
	}
	xprintf("Building Go toolchain1 using %s.\n", goroot_bootstrap)

	mkzbootstrap(pathf("%s/src/cmd/internal/objabi/zbootstrap.go", goroot))

	// Use $GOROOT/pkg/bootstrap as the bootstrap workspace root.
	// We use a subdirectory of $GOROOT/pkg because that's the
	// space within $GOROOT where we store all generated objects.
	// We could use a temporary directory outside $GOROOT instead,
	// but it is easier to debug on failure if the files are in a known location.
	workspace := pathf("%s/pkg/bootstrap", goroot)
	xremoveall(workspace)
	xatexit(func() { xremoveall(workspace) })
	base := pathf("%s/src/bootstrap", workspace)
	xmkdirall(base)

	// Copy source code into $GOROOT/pkg/bootstrap and rewrite import paths.
	writefile("module bootstrap\n", pathf("%s/%s", base, "go.mod"), 0)
	for _, dir := range bootstrapDirs {
	src := pathf("%s/src/%s", goroot, dir)
	dst := pathf("%s/%s", base, dir)
	xmkdirall(dst)
	if dir == "cmd/cgo" {
	// Write to src because we need the file both for bootstrap
	// and for later in the main build.
	mkzdefaultcc("", pathf("%s/zdefaultcc.go", src))
	}
	Dir:
	for _, name := range xreaddirfiles(src) {
	for _, pre := range ignorePrefixes {
	if strings.HasPrefix(name, pre) {
	continue Dir
	}
	}
	for _, suf := range ignoreSuffixes {
	if strings.HasSuffix(name, suf) {
	continue Dir
	}
	}
	srcFile := pathf("%s/%s", src, name)
	dstFile := pathf("%s/%s", dst, name)
	text := bootstrapRewriteFile(srcFile)
	writefile(text, dstFile, 0)
	}
	}

	// Set up environment for invoking Go 1.4 go command.
	// GOROOT points at Go 1.4 GOROOT,
	// GOPATH points at our bootstrap workspace,
	// GOBIN is empty, so that binaries are installed to GOPATH/bin,
	// and GOOS, GOHOSTOS, GOARCH, and GOHOSTOS are empty,
	// so that Go 1.4 builds whatever kind of binary it knows how to build.
	// Restore GOROOT, GOPATH, and GOBIN when done.
	// Don't bother with GOOS, GOHOSTOS, GOARCH, and GOHOSTARCH,
	// because setup will take care of those when bootstrapBuildTools returns.

	defer os.Setenv("GOROOT", os.Getenv("GOROOT"))
	os.Setenv("GOROOT", goroot_bootstrap)

	defer os.Setenv("GOPATH", os.Getenv("GOPATH"))
	os.Setenv("GOPATH", workspace)

	defer os.Setenv("GOBIN", os.Getenv("GOBIN"))
	os.Setenv("GOBIN", "")

	os.Setenv("GOOS", "")
	os.Setenv("GOHOSTOS", "")
	os.Setenv("GOARCH", "")
	os.Setenv("GOHOSTARCH", "")

	// Run Go 1.4 to build binaries. Use -gcflags=-l to disable inlining to
	// workaround bugs in Go 1.4's compiler. See discussion thread:
	// https://groups.google.com/d/msg/golang-dev/Ss7mCKsvk8w/Gsq7VYI0AwAJ
	// Use the math_big_pure_go build tag to disable the assembly in math/big
	// which may contain unsupported instructions.
	// Note that if we are using Go 1.10 or later as bootstrap, the -gcflags=-l
	// only applies to the final cmd/go binary, but that's OK: if this is Go 1.10
	// or later we don't need to disable inlining to work around bugs in the Go 1.4 compiler.
	cmd := []string{
	pathf("%s/bin/go", goroot_bootstrap),
	"install",
	"-gcflags=-l",
	"-tags=math_big_pure_go compiler_bootstrap",
	}
	if vflag > 0 {
	cmd = append(cmd, "-v")
	}
	if tool := os.Getenv("GOBOOTSTRAP_TOOLEXEC"); tool != "" {
	cmd = append(cmd, "-toolexec="+tool)
	}
	cmd = append(cmd, "bootstrap/cmd/...")
	run(base, ShowOutput\|CheckExit, cmd...)

	// Copy binaries into tool binary directory.
	for _, name := range bootstrapDirs {
	if !strings.HasPrefix(name, "cmd/") {
	continue
	}
	name = name[len("cmd/"):]
	if !strings.Contains(name, "/") {
	copyfile(pathf("%s/%s%s", tooldir, name, exe), pathf("%s/bin/%s%s", workspace, name, exe), writeExec)
	}
	}

	if vflag > 0 {
	xprintf("\n")
	}
	}

	var ssaRewriteFileSubstring = filepath.FromSlash("src/cmd/compile/internal/ssa/rewrite")

	// isUnneededSSARewriteFile reports whether srcFile is a
	// src/cmd/compile/internal/ssa/rewriteARCHNAME.go file for an
	// architecture that isn't for the current runtime.GOARCH.
	//
	// When unneeded is true archCaps is the rewrite base filename without
	// the "rewrite" prefix or ".go" suffix: AMD64, 386, ARM, ARM64, etc.
	func isUnneededSSARewriteFile(srcFile string) (archCaps string, unneeded bool) {
	if !strings.Contains(srcFile, ssaRewriteFileSubstring) {
	return "", false
	}
	fileArch := strings.TrimSuffix(strings.TrimPrefix(filepath.Base(srcFile), "rewrite"), ".go")
	if fileArch == "" {
	return "", false
	}
	b := fileArch[0]
	if b == '_' \|\| ('a' <= b && b <= 'z') {
	return "", false
	}
	archCaps = fileArch
	fileArch = strings.ToLower(fileArch)
	fileArch = strings.TrimSuffix(fileArch, "splitload")
	if fileArch == os.Getenv("GOHOSTARCH") {
	return "", false
	}
	if fileArch == strings.TrimSuffix(runtime.GOARCH, "le") {
	return "", false
	}
	if fileArch == strings.TrimSuffix(os.Getenv("GOARCH"), "le") {
	return "", false
	}
	return archCaps, true
	}

	func bootstrapRewriteFile(srcFile string) string {
	// During bootstrap, generate dummy rewrite files for
	// irrelevant architectures. We only need to build a bootstrap
	// binary that works for the current runtime.GOARCH.
	// This saves 6+ seconds of bootstrap.
	if archCaps, ok := isUnneededSSARewriteFile(srcFile); ok {
	return fmt.Sprintf(`// Code generated by go tool dist; DO NOT EDIT.

	package ssa

	func rewriteValue%s(v *Value) bool { panic("unused during bootstrap") }
	func rewriteBlock%s(b *Block) bool { panic("unused during bootstrap") }
	`, archCaps, archCaps)
	}

	return bootstrapFixImports(srcFile)
	}

	func bootstrapFixImports(srcFile string) string {
	lines := strings.SplitAfter(readfile(srcFile), "\n")
	inBlock := false
	for i, line := range lines {
	if strings.HasPrefix(line, "import (") {
	inBlock = true
	continue
	}
	if inBlock && strings.HasPrefix(line, ")") {
	inBlock = false
	continue
	}
	if strings.HasPrefix(line, `import "`) \|\| strings.HasPrefix(line, `import . "`) \|\|
	inBlock && (strings.HasPrefix(line, "\t\"") \|\| strings.HasPrefix(line, "\t. \"")) {
	line = strings.Replace(line, `"cmd/`, `"bootstrap/cmd/`, -1)
	for _, dir := range bootstrapDirs {
	if strings.HasPrefix(dir, "cmd/") {
	continue
	}
	line = strings.Replace(line, `"`+dir+`"`, `"bootstrap/`+dir+`"`, -1)
	}
	lines[i] = line
	}
	}

	lines[0] = "// Code generated by go tool dist; DO NOT EDIT.\n// This is a bootstrap copy of " + srcFile + "\n\n//line " + srcFile + ":1\n" + lines[0]

	return strings.Join(lines, "")
	}