From d0c0180cecfd46203f91b16795cd70156a89b4ba Mon Sep 17 00:00:00 2001
From: Alec Thomas <alec@swapoff.org>
Date: Sat, 28 Aug 2021 16:54:20 +1000
Subject: [PATCH] Hydrate pointers to embedded structs.

---
 build.go     | 13 +++++--------
 kong_test.go | 12 +++++++++---
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/build.go b/build.go
index 85e18dc..f7893be 100644
--- a/build.go
+++ b/build.go
@@ -61,6 +61,11 @@ func flattenedFields(v reflect.Value) (out []flattenedField, err error) {
 		if tag.Ignored {
 			continue
 		}
+		// Command and embedded structs can be pointers, so we hydrate them now.
+		if (tag.Cmd || tag.Embed) && ft.Type.Kind() == reflect.Ptr {
+			fv = reflect.New(ft.Type.Elem()).Elem()
+			v.FieldByIndex(ft.Index).Set(fv.Addr())
+		}
 		if !ft.Anonymous && !tag.Embed {
 			if fv.CanSet() {
 				out = append(out, flattenedField{field: ft, value: fv, tag: tag})
@@ -133,14 +138,6 @@ MAIN:
 			name = tag.Prefix + name
 		}
 
-		fieldType := ft.Type
-		// Hydrate command structs that are pointers.
-		if tag.Cmd && fieldType.Kind() == reflect.Ptr {
-			fv = reflect.New(fieldType.Elem()).Elem()
-			field.value = fv
-			v.FieldByIndex(field.field.Index).Set(fv.Addr())
-		}
-
 		// Nested structs are either commands or args, unless they implement the Mapper interface.
 		if field.value.Kind() == reflect.Struct && (tag.Cmd || tag.Arg) && k.registry.ForValue(fv) == nil {
 			typ := CommandNode
diff --git a/kong_test.go b/kong_test.go
index 7d80d40..6bfd514 100644
--- a/kong_test.go
+++ b/kong_test.go
@@ -1283,19 +1283,25 @@ func TestDuplicateNestedShortFlags(t *testing.T) {
 	require.EqualError(t, err, "<anonymous struct>.Flag2: duplicate short flag -t")
 }
 
-func TestHydratePointerCommands(t *testing.T) {
+func TestHydratePointerCommandsAndEmbeds(t *testing.T) {
 	type cmd struct {
 		Flag bool
 	}
 
+	type embed struct {
+		Embed bool
+	}
+
 	var cli struct {
-		Cmd *cmd `cmd:""`
+		Cmd   *cmd   `cmd:""`
+		Embed *embed `embed:""`
 	}
 
 	k := mustNew(t, &cli)
-	_, err := k.Parse([]string{"cmd", "--flag"})
+	_, err := k.Parse([]string{"--embed", "cmd", "--flag"})
 	require.NoError(t, err)
 	require.Equal(t, &cmd{Flag: true}, cli.Cmd)
+	require.Equal(t, &embed{Embed: true}, cli.Embed)
 }
 
 // nolint