Hide non-user commands from autocomplete output

This PR hides non-user CLI commands from the list of autocomplete
suggestions.

vendor/github.com/mitchellh/cli/cli.go

@@ -59,8 +59,20 @@ type CLI struct {
 	// For example, if the key is "foo bar", then to access it our CLI
 	// must be accessed with "./cli foo bar". See the docs for CLI for
 	// notes on how this changes some other behavior of the CLI as well.
+	//
+	// The factory should be as cheap as possible, ideally only allocating
+	// a struct. The factory may be called multiple times in the course
+	// of a command execution and certain events such as help require the
+	// instantiation of all commands. Expensive initialization should be
+	// deferred to function calls within the interface implementation.
 	Commands map[string]CommandFactory
 
+	// HiddenCommands is a list of commands that are "hidden". Hidden
+	// commands are not given to the help function callback and do not
+	// show up in autocomplete. The values in the slice should be equivalent
+	// to the keys in the command map.
+	HiddenCommands []string
+
 	// Name defines the name of the CLI.
 	Name string
 
@@ -116,6 +128,7 @@ type CLI struct {
 	autocomplete   *complete.Complete
 	commandTree    *radix.Tree
 	commandNested  bool
+	commandHidden  map[string]struct{}
 	subcommand     string
 	subcommandArgs []string
 	topFlags       []string
@@ -298,6 +311,14 @@ func (c *CLI) init() {
 		c.HelpWriter = os.Stderr
 	}
 
+	// Build our hidden commands
+	if len(c.HiddenCommands) > 0 {
+		c.commandHidden = make(map[string]struct{})
+		for _, h := range c.HiddenCommands {
+			c.commandHidden[h] = struct{}{}
+		}
+	}
+
 	// Build our command tree
 	c.commandTree = radix.New()
 	c.commandNested = false
@@ -419,6 +440,11 @@ func (c *CLI) initAutocompleteSub(prefix string) complete.Command {
 			return false
 		}
 
+		// If the command is hidden, don't record it at all
+		if _, ok := c.commandHidden[fullKey]; ok {
+			return false
+		}
+
 		if cmd.Sub == nil {
 			cmd.Sub = complete.Commands(make(map[string]complete.Command))
 		}
@@ -566,6 +592,11 @@ func (c *CLI) helpCommands(prefix string) map[string]CommandFactory {
 			panic("not found: " + k)
 		}
 
+		// If this is a hidden command, don't show it
+		if _, ok := c.commandHidden[k]; ok {
+			continue
+		}
+
 		result[k] = raw.(CommandFactory)
 	}