From 72e54a1d0c9c11fe565479370ea705354d5d0727 Mon Sep 17 00:00:00 2001
From: Scott Wisniewski <scott@scottdw2.com>
Date: Sat, 19 Mar 2022 13:31:36 -0700
Subject: [PATCH] One more round of PR Feedback.

Make negatable bool * work.
---
 context.go   | 21 ++++++++++++++++++++-
 kong_test.go | 29 ++++++++++++++++++++++++++++-
 tag.go       |  4 +++-
 3 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/context.go b/context.go
index a97edb0..cefe728 100644
--- a/context.go
+++ b/context.go
@@ -663,6 +663,22 @@ func (c *Context) Apply() (string, error) {
 	return strings.Join(path, " "), nil
 }
 
+func flipBoolValue(value reflect.Value) error {
+	if value.Kind() == reflect.Bool {
+		value.SetBool(!value.Bool())
+		return nil
+	}
+
+	if value.Kind() == reflect.Ptr {
+		if !value.IsNil() {
+			return flipBoolValue(value.Elem())
+		}
+		return nil
+	}
+
+	return fmt.Errorf("cannot negate a value of %s", value.Type().String())
+}
+
 func (c *Context) parseFlag(flags []*Flag, match string) (err error) {
 	candidates := []string{}
 	for _, flag := range flags {
@@ -690,7 +706,10 @@ func (c *Context) parseFlag(flags []*Flag, match string) (err error) {
 		}
 		if flag.Negated {
 			value := c.getValue(flag.Value)
-			value.SetBool(!value.Bool())
+			err := flipBoolValue(value)
+			if err != nil {
+				return err
+			}
 			flag.Value.Apply(value)
 		}
 		c.Path = append(c.Path, &Path{Flag: flag})
diff --git a/kong_test.go b/kong_test.go
index 49ae4f5..1b2e1ea 100644
--- a/kong_test.go
+++ b/kong_test.go
@@ -1660,7 +1660,7 @@ func TestBoolPtr(t *testing.T) {
 	require.Equal(t, true, *cli.X)
 }
 
-func TestBoolPtrNegated(t *testing.T) {
+func TestBoolPtrFalse(t *testing.T) {
 	var cli struct {
 		X *bool
 	}
@@ -1674,6 +1674,33 @@ func TestBoolPtrNegated(t *testing.T) {
 	require.Equal(t, false, *cli.X)
 }
 
+func TestBoolPtrNegated(t *testing.T) {
+	var cli struct {
+		X *bool `negatable:""`
+	}
+	k, err := kong.New(&cli)
+	require.NoError(t, err)
+	require.NotNil(t, k)
+	ctx, err := k.Parse([]string{"--no-x"})
+	require.NoError(t, err)
+	require.NotNil(t, ctx)
+	require.NotNil(t, cli.X)
+	require.Equal(t, false, *cli.X)
+}
+
+func TestNilNegatableBoolPtr(t *testing.T) {
+	var cli struct {
+		X *bool `negatable:""`
+	}
+	k, err := kong.New(&cli)
+	require.NoError(t, err)
+	require.NotNil(t, k)
+	ctx, err := k.Parse([]string{})
+	require.NoError(t, err)
+	require.NotNil(t, ctx)
+	require.Nil(t, cli.X)
+}
+
 func TestBoolPtrNil(t *testing.T) {
 	var cli struct {
 		X *bool
diff --git a/tag.go b/tag.go
index 25cd242..b471613 100644
--- a/tag.go
+++ b/tag.go
@@ -169,9 +169,11 @@ func parseTag(parent reflect.Value, ft reflect.StructField) (*Tag, error) {
 func hydrateTag(t *Tag, typ reflect.Type) error { // nolint: gocyclo
 	var typeName string
 	var isBool bool
+	var isBoolPtr bool
 	if typ != nil {
 		typeName = typ.Name()
 		isBool = typ.Kind() == reflect.Bool
+		isBoolPtr = typ.Kind() == reflect.Ptr && typ.Elem().Kind() == reflect.Bool
 	}
 	var err error
 	t.Cmd = t.Has("cmd")
@@ -212,7 +214,7 @@ func hydrateTag(t *Tag, typ reflect.Type) error { // nolint: gocyclo
 	t.EnvPrefix = t.Get("envprefix")
 	t.Embed = t.Has("embed")
 	negatable := t.Has("negatable")
-	if negatable && !isBool {
+	if negatable && !isBool && !isBoolPtr {
 		return fmt.Errorf("negatable can only be set on booleans")
 	}
 	t.Negatable = negatable