stop flag parsing after terminator --

Signed-off-by: David Wadden <dwadden@pivotal.io>

app_test.go

@@ -192,6 +192,50 @@ func TestApp_CommandWithArgBeforeFlags(t *testing.T) {
 	expect(t, firstArg, "my-arg")
 }
 
+func TestApp_CommandWithFlagBeforeTerminator(t *testing.T) {
+	var parsedOption string
+	var args []string
+
+	app := cli.NewApp()
+	command := cli.Command{
+		Name: "cmd",
+		Flags: []cli.Flag{
+			cli.StringFlag{Name: "option", Value: "", Usage: "some option"},
+		},
+		Action: func(c *cli.Context) {
+			parsedOption = c.String("option")
+			args = c.Args()
+		},
+	}
+	app.Commands = []cli.Command{command}
+
+	app.Run([]string{"", "cmd", "my-arg", "--option", "my-option", "--", "--notARealFlag"})
+
+	expect(t, parsedOption, "my-option")
+	expect(t, args[0], "my-arg")
+	expect(t, args[1], "--")
+	expect(t, args[2], "--notARealFlag")
+}
+
+func TestApp_CommandWithNoFlagBeforeTerminator(t *testing.T) {
+	var args []string
+
+	app := cli.NewApp()
+	command := cli.Command{
+		Name: "cmd",
+		Action: func(c *cli.Context) {
+			args = c.Args()
+		},
+	}
+	app.Commands = []cli.Command{command}
+
+	app.Run([]string{"", "cmd", "my-arg", "--", "notAFlagAtAll"})
+
+	expect(t, args[0], "my-arg")
+	expect(t, args[1], "--")
+	expect(t, args[2], "notAFlagAtAll")
+}
+
 func TestApp_Float64Flag(t *testing.T) {
 	var meters float64
 

command.go

@@ -56,18 +56,30 @@ func (c Command) Run(ctx *Context) error {
 	set.SetOutput(ioutil.Discard)
 
 	firstFlagIndex := -1
+	terminatorIndex := -1
 	for index, arg := range ctx.Args() {
-		if strings.HasPrefix(arg, "-") {
-			firstFlagIndex = index
+		if arg == "--" {
+			terminatorIndex = index
 			break
+		} else if strings.HasPrefix(arg, "-") && firstFlagIndex == -1 {
+			firstFlagIndex = index
 		}
 	}
 
 	var err error
 	if firstFlagIndex > -1 && !c.SkipFlagParsing {
 		args := ctx.Args()
-		regularArgs := args[1:firstFlagIndex]
-		flagArgs := args[firstFlagIndex:]
+		regularArgs := make([]string, len(args[1:firstFlagIndex]))
+		copy(regularArgs, args[1:firstFlagIndex])
+
+		var flagArgs []string
+		if terminatorIndex > -1 {
+			flagArgs = args[firstFlagIndex:terminatorIndex]
+			regularArgs = append(regularArgs, args[terminatorIndex:]...)
+		} else {
+			flagArgs = args[firstFlagIndex:]
+		}
+
 		err = set.Parse(append(flagArgs, regularArgs...))
 	} else {
 		err = set.Parse(ctx.Args().Tail())