1 files changed, 50 insertions, 37 deletions

diff --git a/libgo/go/cmd/go/internal/help/help.go b/libgo/go/cmd/go/internal/help/help.go
index b4c5217f836..a80afe36c41 100644
--- a/libgo/go/cmd/go/internal/help/help.go
+++ b/libgo/go/cmd/go/internal/help/help.go
@@ -21,82 +21,95 @@ import (
 
 // Help implements the 'help' command.
 func Help(args []string) {
-	if len(args) == 0 {
-		PrintUsage(os.Stdout)
-		// not exit 2: succeeded at 'go help'.
-		return
-	}
-	if len(args) != 1 {
-		fmt.Fprintf(os.Stderr, "usage: go help command\n\nToo many arguments given.\n")
-		os.Exit(2) // failed at 'go help'
-	}
-
-	arg := args[0]
-
 	// 'go help documentation' generates doc.go.
-	if arg == "documentation" {
+	if len(args) == 1 && args[0] == "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("// Code generated by mkalldocs.sh; DO NOT EDIT.")
 		fmt.Println("// Edit the documentation in other files and rerun mkalldocs.sh to generate this one.")
 		fmt.Println()
 		buf := new(bytes.Buffer)
-		PrintUsage(buf)
+		PrintUsage(buf, base.Go)
 		usage := &base.Command{Long: buf.String()}
-		tmpl(&commentWriter{W: os.Stdout}, documentationTemplate, append([]*base.Command{usage}, base.Commands...))
+		cmds := []*base.Command{usage}
+		for _, cmd := range base.Go.Commands {
+			if cmd.UsageLine == "gopath-get" {
+				// Avoid duplication of the "get" documentation.
+				continue
+			}
+			cmds = append(cmds, cmd)
+			cmds = append(cmds, cmd.Commands...)
+		}
+		tmpl(&commentWriter{W: os.Stdout}, documentationTemplate, cmds)
 		fmt.Println("package main")
 		return
 	}
 
-	for _, cmd := range base.Commands {
-		if cmd.Name() == arg {
-			tmpl(os.Stdout, helpTemplate, cmd)
-			// not exit 2: succeeded at 'go help cmd'.
-			return
+	cmd := base.Go
+Args:
+	for i, arg := range args {
+		for _, sub := range cmd.Commands {
+			if sub.Name() == arg {
+				cmd = sub
+				continue Args
+			}
+		}
+
+		// helpSuccess is the help command using as many args as possible that would succeed.
+		helpSuccess := "go help"
+		if i > 0 {
+			helpSuccess = " " + strings.Join(args[:i], " ")
 		}
+		fmt.Fprintf(os.Stderr, "go help %s: unknown help topic. Run '%s'.\n", strings.Join(args, " "), helpSuccess)
+		os.Exit(2) // failed at 'go help cmd'
 	}
 
-	fmt.Fprintf(os.Stderr, "Unknown help topic %#q. Run 'go help'.\n", arg)
-	os.Exit(2) // failed at 'go help cmd'
+	if len(cmd.Commands) > 0 {
+		PrintUsage(os.Stdout, cmd)
+	} else {
+		tmpl(os.Stdout, helpTemplate, cmd)
+	}
+	// not exit 2: succeeded at 'go help cmd'.
+	return
 }
 
-var usageTemplate = `Go is a tool for managing Go source code.
+var usageTemplate = `{{.Long | trim}}
 
 Usage:
 
-	go command [arguments]
+	{{.UsageLine}} <command> [arguments]
 
 The commands are:
-{{range .}}{{if .Runnable}}
+{{range .Commands}}{{if or (.Runnable) .Commands}}
 	{{.Name | printf "%-11s"}} {{.Short}}{{end}}{{end}}
 
-Use "go help [command]" for more information about a command.
-
+Use "go help{{with .LongName}} {{.}}{{end}} <command>" for more information about a command.
+{{if eq (.UsageLine) "go"}}
 Additional help topics:
-{{range .}}{{if not .Runnable}}
+{{range .Commands}}{{if and (not .Runnable) (not .Commands)}}
 	{{.Name | printf "%-11s"}} {{.Short}}{{end}}{{end}}
 
-Use "go help [topic]" for more information about that topic.
-
+Use "go help{{with .LongName}} {{.}}{{end}} <topic>" for more information about that topic.
+{{end}}
 `
 
-var helpTemplate = `{{if .Runnable}}usage: go {{.UsageLine}}
+var helpTemplate = `{{if .Runnable}}usage: {{.UsageLine}}
 
 {{end}}{{.Long | trim}}
 `
 
 var documentationTemplate = `{{range .}}{{if .Short}}{{.Short | capitalize}}
 
-{{end}}{{if .Runnable}}Usage:
+{{end}}{{if .Commands}}` + usageTemplate + `{{else}}{{if .Runnable}}Usage:
 
-	go {{.UsageLine}}
+	{{.UsageLine}}
 
 {{end}}{{.Long | trim}}
 
 
-{{end}}`
+{{end}}{{end}}`
 
 // commentWriter writes a Go comment to the underlying io.Writer,
 // using line comment form (//).
@@ -171,8 +184,8 @@ func capitalize(s string) string {
 	return string(unicode.ToTitle(r)) + s[n:]
 }
 
-func PrintUsage(w io.Writer) {
+func PrintUsage(w io.Writer, cmd *base.Command) {
 	bw := bufio.NewWriter(w)
-	tmpl(bw, usageTemplate, base.Commands)
+	tmpl(bw, usageTemplate, cmd)
 	bw.Flush()
 }