From de4b665298ab33496c036d15260f0c98a0ce7fbd Mon Sep 17 00:00:00 2001
From: Shannon Booth <shannon@serenityos.org>
Date: Fri, 29 May 2026 21:47:42 +0200
Subject: [PATCH] AK: Fix rvalue Variant downcast to variant aliases

Pass the required TypeWrapper through the rvalue downcast<Variant<...>>
path, matching the existing const& overload.
---
 AK/Variant.h             | 2 +-
 Tests/AK/TestVariant.cpp | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/AK/Variant.h b/AK/Variant.h
index b812b362af..17d81debec 100644
--- a/AK/Variant.h
+++ b/AK/Variant.h
@@ -430,7 +430,7 @@ public:
     decltype(auto) downcast() &&
     {
         if constexpr (sizeof...(NewTs) == 1 && (IsSpecializationOf<NewTs, Variant> && ...)) {
-            return move(*this).template downcast_variant<NewTs...>();
+            return move(*this).downcast_variant(TypeWrapper<NewTs...> {});
         } else {
             Variant<NewTs...> instance { Variant<NewTs...>::invalid_index, Detail::VariantConstructTag {} };
             visit([&](auto& value) {
diff --git a/Tests/AK/TestVariant.cpp b/Tests/AK/TestVariant.cpp
index d97f58019a..9ed2631961 100644
--- a/Tests/AK/TestVariant.cpp
+++ b/Tests/AK/TestVariant.cpp
@@ -132,6 +132,11 @@ TEST_CASE(as)
     EXPECT(one_integer_to_rule_them_all.has<i8>());
     EXPECT_EQ(fake_integer.get<i8>(), 60);
     EXPECT_EQ(one_integer_to_rule_them_all.get<i8>(), 60);
+
+    using OptionalFancyType = Variant<i8, i16, Empty>;
+    auto definitely_fancy = OptionalFancyType { static_cast<i16>(12) }.downcast<SomeFancyType>();
+    EXPECT(definitely_fancy.has<i16>());
+    EXPECT_EQ(definitely_fancy.get<i16>(), 12);
 }
 
 TEST_CASE(moved_from_state)