The ultimate --help & spelling suggester handler

- short command usage output now lists subcommands instead of flags for
  parent commands

- mistyping a subcommand now results in a non-zero exit status

- requesting `--help` or `-h` for any command now prints help docs on
  stdout and exits with 0

cmd/gh/main.go

@@ -56,6 +56,9 @@ func main() {
 		printError(os.Stderr, err, cmd, hasDebug)
 		os.Exit(1)
 	}
+	if command.HasFailed() {
+		os.Exit(1)
+	}
 
 	newRelease := <-updateMessageChan
 	if newRelease != nil {

command/help.go

@@ -12,6 +12,18 @@ import (
 func rootUsageFunc(command *cobra.Command) error {
 	command.Printf("Usage:  %s", command.UseLine())
 
+	subcommands := command.Commands()
+	if len(subcommands) > 0 {
+		command.Print("\n\nAvailable commands:\n")
+		for _, c := range subcommands {
+			if c.Hidden {
+				continue
+			}
+			command.Printf("  %s\n", c.Name())
+		}
+		return nil
+	}
+
 	flagUsages := command.LocalFlags().FlagUsages()
 	if flagUsages != "" {
 		command.Printf("\n\nFlags:\n%s", flagUsages)
@@ -19,32 +31,40 @@ func rootUsageFunc(command *cobra.Command) error {
 	return nil
 }
 
-func rootHelpFunc(command *cobra.Command, args []string) {
-	// Display helpful error message in case subcommand name was mistyped.
-	// This matches Cobra's behavior for root command, which Cobra
-	// confusingly doesn't apply to nested commands.
-	if command != RootCmd {
-		if command.Parent() == RootCmd && len(args) >= 2 {
-			if command.SuggestionsMinimumDistance <= 0 {
-				command.SuggestionsMinimumDistance = 2
-			}
-			candidates := command.SuggestionsFor(args[1])
+var hasFailed bool
 
-			errOut := command.OutOrStderr()
-			fmt.Fprintf(errOut, "unknown command %q for %q\n", args[1], "gh "+args[0])
+// HasFailed signals that the main process should exit with non-zero status
+func HasFailed() bool {
+	return hasFailed
+}
 
-			if len(candidates) > 0 {
-				fmt.Fprint(errOut, "\nDid you mean this?\n")
-				for _, c := range candidates {
-					fmt.Fprintf(errOut, "\t%s\n", c)
-				}
-				fmt.Fprint(errOut, "\n")
-			}
+// Display helpful error message in case subcommand name was mistyped.
+// This matches Cobra's behavior for root command, which Cobra
+// confusingly doesn't apply to nested commands.
+func nestedSuggestFunc(command *cobra.Command, arg string) {
+	command.Printf("unknown command %q for `%s`\n", arg, command.UseLine())
 
-			oldOut := command.OutOrStdout()
-			command.SetOut(errOut)
-			defer command.SetOut(oldOut)
+	if command.SuggestionsMinimumDistance <= 0 {
+		command.SuggestionsMinimumDistance = 2
+	}
+	candidates := command.SuggestionsFor(arg)
+
+	if len(candidates) > 0 {
+		command.Print("\nDid you mean this?\n")
+		for _, c := range candidates {
+			command.Printf("\t%s\n", c)
 		}
+		command.Print("\n")
+	}
+
+	_ = rootUsageFunc(command)
+}
+
+func rootHelpFunc(command *cobra.Command, args []string) {
+	if command.Parent() == RootCmd && len(args) >= 2 && args[1] != "--help" && args[1] != "-h" {
+		nestedSuggestFunc(command, args[1])
+		hasFailed = true
+		return
 	}
 
 	coreCommands := []string{}