Merge pull request mitchellh#82 from mitchellh/noop-autocomplete

Noop autocomplete setup if we're not autocompleting

cli.go

@@ -3,6 +3,7 @@ package cli
 import (
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"regexp"
 	"sort"
@@ -403,6 +404,16 @@ func (c *CLI) initAutocomplete() {
 		c.autocompleteInstaller = &realAutocompleteInstaller{}
 	}
 
+	// We first set c.autocomplete to a noop autocompleter that outputs
+	// to nul so that we can detect if we're autocompleting or not. If we're
+	// not, then we do nothing. This saves a LOT of compute cycles since
+	// initAutoCompleteSub has to walk every command.
+	c.autocomplete = complete.New(c.Name, complete.Command{})
+	c.autocomplete.Out = ioutil.Discard
+	if !c.autocomplete.Complete() {
+		return
+	}
+
 	// Build the root command
 	cmd := c.initAutocompleteSub("")
 

cli_test.go

@@ -1412,6 +1412,10 @@ func TestCLIAutocomplete_subcommandArgs(t *testing.T) {
 				Autocomplete: true,
 			}
 
+			// We need to initialize the autocomplete environment so that
+			// the cli doesn't no-op the autocomplete init
+			defer testAutocomplete(t, "must be non-empty")()
+
 			// Initialize
 			cli.init()