Implement code review feedback

context.go

@@ -649,7 +649,7 @@ func (c *Context) parseFlag(flags []*Flag, match string) (err error) {
 		if flag.Short != 0 {
 			candidates = append(candidates, short)
 		}
-		if short != match && long != match && neg != match {
+		if short != match && long != match && !(match == neg && flag.Tag.Negatable) {
 			continue
 		}
 		// Found a matching flag.

kong_test.go

@@ -382,6 +382,21 @@ func TestInvertedNegatedBooleanFlag(t *testing.T) {
 	require.Equal(t, true, cli.Cmd.Flag)
 }
 
+func TestExistingNoFlag(t *testing.T) {
+	var cli struct {
+		Cmd struct {
+			Flag   bool `kong:"default='true'"`
+			NoFlag string
+		} `kong:"cmd"`
+	}
+
+	p := mustNew(t, &cli)
+	_, err := p.Parse([]string{"cmd", "--no-flag=none"})
+	require.NoError(t, err)
+	require.Equal(t, true, cli.Cmd.Flag)
+	require.Equal(t, "none", cli.Cmd.NoFlag)
+}
+
 func TestInvalidNegatedNonBool(t *testing.T) {
 	var cli struct {
 		Cmd struct {

tag.go

@@ -160,7 +160,7 @@ func parseTag(fv reflect.Value, ft reflect.StructField) *Tag {
 	t.Prefix = t.Get("prefix")
 	t.Embed = t.Has("embed")
 	negatable := t.Has("negatable")
-	if negatable && ft.Type.Name() != "bool" {
+	if negatable && ft.Type.Kind() != reflect.Bool {
 		fail("negatable can only be set on booleans")
 	}
 	t.Negatable = negatable