Complete hidden commands flags and its subcommands

This change enable to have a correct completion on hidden commands flags and
its subcommands if present, when using bash.
If an exact hidden command is typed on the command line and then the
user request completion, instead of printing other available subcommand
at the same level (which is thus incorrect), it will print any of its
subcommand if available.
Flags completion request (starting with -) will also work as expected,
as well as flag completion request on any subcommand (persistent flags
or local).

Merge spf13/cobra#983

Fixes spf13/cobra#981

bash_completions.go

@@ -293,6 +293,7 @@ __%[1]s_handle_flag()
     # if you set a flag which only applies to this command, don't show subcommands
     if __%[1]s_contains_word "${flagname}" "${local_nonpersistent_flags[@]}"; then
       commands=()
+      hidden_commands=()
     fi
 
     # keep flag value with flagname as flaghash
@@ -314,6 +315,7 @@ __%[1]s_handle_flag()
         # if we are looking for a flags value, don't show commands
         if [[ $c -eq $cword ]]; then
             commands=()
+            hidden_commands=()
         fi
     fi
 
@@ -365,6 +367,8 @@ __%[1]s_handle_word()
         __%[1]s_handle_flag
     elif __%[1]s_contains_word "${words[c]}" "${commands[@]}"; then
         __%[1]s_handle_command
+    elif __%[1]s_contains_word "${words[c]}" "${hidden_commands[@]}"; then
+        __%[1]s_handle_command
     elif [[ $c -eq 0 ]]; then
         __%[1]s_handle_command
     elif __%[1]s_contains_word "${words[c]}" "${command_aliases[@]}"; then
@@ -432,10 +436,14 @@ fi
 func writeCommands(buf io.StringWriter, cmd *Command) {
 	WriteStringAndCheck(buf, "    commands=()\n")
 	for _, c := range cmd.Commands() {
-		if !c.IsAvailableCommand() && c != cmd.helpCommand {
+		if !c.IsAvailableCommand() && !c.Hidden && c != cmd.helpCommand {
 			continue
 		}
-		WriteStringAndCheck(buf, fmt.Sprintf("    commands+=(%q)\n", c.Name()))
+		commands := "commands"
+		if c.Hidden {
+			commands = "hidden_commands"
+		}
+		WriteStringAndCheck(buf, fmt.Sprintf("    %s+=(%q)\n", commands, c.Name()))
 		writeCmdAliases(buf, c)
 	}
 	WriteStringAndCheck(buf, "\n")
@@ -639,7 +647,7 @@ func writeArgAliases(buf io.StringWriter, cmd *Command) {
 
 func gen(buf io.StringWriter, cmd *Command) {
 	for _, c := range cmd.Commands() {
-		if !c.IsAvailableCommand() && c != cmd.helpCommand {
+		if !c.IsAvailableCommand() && !c.Hidden && c != cmd.helpCommand {
 			continue
 		}
 		gen(buf, c)

bash_completions_test.go

@@ -131,6 +131,22 @@ func TestBashCompletions(t *testing.T) {
 		Run:        emptyRun,
 	}
 
+	hiddenCmd := &Command{
+		Use:    "hidden",
+		Short:  "A command which is hidden",
+		Long:   "an absolutely utterly useless command for testing for testing hiding.",
+		Hidden: true,
+		Run:    emptyRun,
+	}
+
+	hiddenSubCmd := &Command{
+		Use:    "subcommandForHidden",
+		Short:  "A command which is attached to a hidden one",
+		Long:   "an absolutely utterly useless command for testing for testing subcommand attached to hidden one.",
+		Hidden: true,
+		Run:    emptyRun,
+	}
+
 	colonCmd := &Command{
 		Use: "cmd:colon",
 		Run: emptyRun,
@@ -147,7 +163,8 @@ func TestBashCompletions(t *testing.T) {
 	}
 
 	echoCmd.AddCommand(timesCmd)
-	rootCmd.AddCommand(echoCmd, printCmd, deprecatedCmd, colonCmd)
+	hiddenCmd.AddCommand(hiddenSubCmd)
+	rootCmd.AddCommand(echoCmd, printCmd, deprecatedCmd, hiddenCmd, colonCmd)
 
 	buf := new(bytes.Buffer)
 	assertNoErr(t, rootCmd.GenBashCompletion(buf))
@@ -203,6 +220,13 @@ func TestBashCompletions(t *testing.T) {
 
 	checkOmit(t, output, deprecatedCmd.Name())
 
+	// check that hidden command and its subcommand functions are available
+	check(t, output, "_root_hidden")
+	check(t, output, "_root_hidden_subcommandForHidden")
+	checkOmit(t, output, ` commands+=("hidden")`)
+	check(t, output, `hidden_commands+=("hidden")`)
+	check(t, output, `commands+=("subcommandForHidden")`)
+
 	// If available, run shellcheck against the script.
 	if err := exec.Command("which", "shellcheck").Run(); err != nil {
 		return