cmd/go: remove invalid space in import comment docs

Generate package comment in alldocs.go using line comments rather than
general comments. This scales better, general comments cannot contain the
"*/" character sequence. Line comments do not have any restrictions on
the comment text that can be contained.

Remove the dependency on sed, which is not cross-platform, not go-gettable
external command.

Remove trailing whitespace from usage string in test.go. It's unnecessary.

Fixes #16030.

Change-Id: I3c0bc9955e7c7603c3d1fb4878218b0719d02e04
Reviewed-on: https://go-review.googlesource.com/23968
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/main.go

@@ -214,15 +214,7 @@ var helpTemplate = `{{if .Runnable}}usage: go {{.UsageLine}}
 {{end}}{{.Long | trim}}
 `
 
-var documentationTemplate = `// Copyright 2011 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.
-
-// DO NOT EDIT THIS FILE. GENERATED BY mkalldocs.sh.
-// Edit the documentation in other files and rerun mkalldocs.sh to generate this one.
-
-/*
-{{range .}}{{if .Short}}{{.Short | capitalize}}
+var documentationTemplate = `{{range .}}{{if .Short}}{{.Short | capitalize}}
 
 {{end}}{{if .Runnable}}Usage:
 
@@ -231,9 +223,39 @@ var documentationTemplate = `// Copyright 2011 The Go Authors. All rights reserv
 {{end}}{{.Long | trim}}
 
 
-{{end}}*/
-package main
-`
+{{end}}`
+
+// commentWriter writes a Go comment to the underlying io.Writer,
+// using line comment form (//).
+type commentWriter struct {
+	W            io.Writer
+	wroteSlashes bool // Wrote "//" at the beginning of the current line.
+}
+
+func (c *commentWriter) Write(p []byte) (int, error) {
+	var n int
+	for i, b := range p {
+		if !c.wroteSlashes {
+			s := "//"
+			if b != '\n' {
+				s = "// "
+			}
+			if _, err := io.WriteString(c.W, s); err != nil {
+				return n, err
+			}
+			c.wroteSlashes = true
+		}
+		n0, err := c.W.Write(p[i : i+1])
+		n += n0
+		if err != nil {
+			return n, err
+		}
+		if b == '\n' {
+			c.wroteSlashes = false
+		}
+	}
+	return len(p), nil
+}
 
 // An errWriter wraps a writer, recording whether a write error occurred.
 type errWriter struct {
@@ -310,10 +332,18 @@ func help(args []string) {
 
 	// 'go help documentation' generates doc.go.
 	if arg == "documentation" {
+		fmt.Println("// Copyright 2011 The Go Authors. All rights reserved.")
+		fmt.Println("// Use of this source code is governed by a BSD-style")
+		fmt.Println("// license that can be found in the LICENSE file.")
+		fmt.Println()
+		fmt.Println("// DO NOT EDIT THIS FILE. GENERATED BY mkalldocs.sh.")
+		fmt.Println("// Edit the documentation in other files and rerun mkalldocs.sh to generate this one.")
+		fmt.Println()
 		buf := new(bytes.Buffer)
 		printUsage(buf)
 		usage := &Command{Long: buf.String()}
-		tmpl(os.Stdout, documentationTemplate, append([]*Command{usage}, commands...))
+		tmpl(&commentWriter{W: os.Stdout}, documentationTemplate, append([]*Command{usage}, commands...))
+		fmt.Println("package main")
 		return
 	}
 

src/cmd/go/mkalldocs.sh

@@ -6,7 +6,6 @@
 set -e
 
 go build -o go.latest
-./go.latest help documentation | sed 's; \*/; * /;' >alldocs.go
+./go.latest help documentation >alldocs.go
 gofmt -w alldocs.go
 rm go.latest
-