From 3561b138f60b00f47a87cda799d3129b11d3a888 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34@live.cn>
Date: Wed, 9 Jul 2025 15:39:31 +0800
Subject: [PATCH] [libc++] Remove the `packaged_task::result_type` extension

No escape hatch added, as there doesn't seem anyone critically relying
on this.
---
 libcxx/docs/ReleaseNotes/21.rst               |  2 +-
 libcxx/include/future                         |  8 -----
 .../futures/futures.task/types.pass.cpp       | 34 -------------------
 .../futures.task.members/type.verify.cpp}     | 14 +++-----
 4 files changed, 5 insertions(+), 53 deletions(-)
 delete mode 100644 libcxx/test/libcxx/thread/futures/futures.task/types.pass.cpp
 rename libcxx/test/{libcxx/thread/futures/futures.task/type.depr.verify.cpp => std/thread/futures/futures.task/futures.task.members/type.verify.cpp} (62%)

diff --git a/libcxx/docs/ReleaseNotes/21.rst b/libcxx/docs/ReleaseNotes/21.rst
index 2cb560b3852f3..30c2159304b03 100644
--- a/libcxx/docs/ReleaseNotes/21.rst
+++ b/libcxx/docs/ReleaseNotes/21.rst
@@ -98,7 +98,7 @@ Deprecations and Removals
 - libc++ no longer adds ``constexpr`` to ``std::hash<std::vector<bool, A>>::operator()``, as the ``constexpr`` addition
   since C++20 was an unintended extension.
 
-- TODO: The non-conforming extension ``packaged_task::result_type`` has been removed in LLVM 21.
+- The non-conforming extension ``packaged_task::result_type`` has been removed in LLVM 21.
 
 Potentially breaking changes
 ----------------------------
diff --git a/libcxx/include/future b/libcxx/include/future
index 31932aeeb6b82..abdd82dc95dd7 100644
--- a/libcxx/include/future
+++ b/libcxx/include/future
@@ -322,8 +322,6 @@ template <class R, class... ArgTypes>
 class packaged_task<R(ArgTypes...)>
 {
 public:
-    typedef R result_type; // extension
-
     // construction and destruction
     packaged_task() noexcept;
     template <class F>
@@ -1605,9 +1603,6 @@ inline _Rp __packaged_task_function<_Rp(_ArgTypes...)>::operator()(_ArgTypes...
 
 template <class _Rp, class... _ArgTypes>
 class packaged_task<_Rp(_ArgTypes...)> {
-public:
-  using result_type _LIBCPP_DEPRECATED = _Rp; // extension
-
 private:
   __packaged_task_function<_Rp(_ArgTypes...)> __f_;
   promise<_Rp> __p_;
@@ -1699,9 +1694,6 @@ void packaged_task<_Rp(_ArgTypes...)>::reset() {
 
 template <class... _ArgTypes>
 class packaged_task<void(_ArgTypes...)> {
-public:
-  using result_type _LIBCPP_DEPRECATED = void; // extension
-
 private:
   __packaged_task_function<void(_ArgTypes...)> __f_;
   promise<void> __p_;
diff --git a/libcxx/test/libcxx/thread/futures/futures.task/types.pass.cpp b/libcxx/test/libcxx/thread/futures/futures.task/types.pass.cpp
deleted file mode 100644
index 659232caa46ec..0000000000000
--- a/libcxx/test/libcxx/thread/futures/futures.task/types.pass.cpp
+++ /dev/null
@@ -1,34 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// UNSUPPORTED: no-threads
-// UNSUPPORTED: c++03
-
-// <future>
-
-// template<class R, class... ArgTypes>
-//     class packaged_task<R(ArgTypes...)>
-// {
-// public:
-//     typedef R result_type; // extension
-
-// This is a libc++ extension.
-
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS
-
-#include <future>
-#include <type_traits>
-
-struct A {};
-
-int main(int, char**) {
-  static_assert((std::is_same<std::packaged_task<A(int, char)>::result_type, A>::value), "");
-  static_assert((std::is_same<std::packaged_task<void(int, char)>::result_type, void>::value), "");
-
-  return 0;
-}
diff --git a/libcxx/test/libcxx/thread/futures/futures.task/type.depr.verify.cpp b/libcxx/test/std/thread/futures/futures.task/futures.task.members/type.verify.cpp
similarity index 62%
rename from libcxx/test/libcxx/thread/futures/futures.task/type.depr.verify.cpp
rename to libcxx/test/std/thread/futures/futures.task/futures.task.members/type.verify.cpp
index 4065637e9eb2a..72171c99a6122 100644
--- a/libcxx/test/libcxx/thread/futures/futures.task/type.depr.verify.cpp
+++ b/libcxx/test/std/thread/futures/futures.task/futures.task.members/type.verify.cpp
@@ -11,18 +11,12 @@
 
 // <future>
 
-// template<class R, class... ArgTypes>
-//     class packaged_task<R(ArgTypes...)>
-// {
-// public:
-//     typedef R result_type; // extension
-
-// This libc++ extension is deprecated. See https://github.com/llvm/llvm-project/issues/112856.
+// Verify that the non-conforming extension packaged_task::result_type is removed.
+// See https://github.com/llvm/llvm-project/issues/112856.
 
 #include <future>
-#include <type_traits>
 
 struct A {};
 
-using RA = std::packaged_task<A(int, char)>::result_type;    // expected-warning {{'result_type' is deprecated}}
-using RV = std::packaged_task<void(int, char)>::result_type; // expected-warning {{'result_type' is deprecated}}
+using RA = std::packaged_task<A(int, char)>::result_type;    // expected-error {{no type named 'result_type'}}
+using RV = std::packaged_task<void(int, char)>::result_type; // expected-error {{no type named 'result_type'}}