[libcxx-commits] [libcxx] 9bde15d - [libc++] Deprecate std::launch::any extension (#173397)

[via libcxx-commits]

Author: sohail
Date: 2026-01-30T13:51:52+08:00
New Revision: 9bde15d76dd8d1c93ce7b9b2e25265f57ac3a9f4

URL: https://github.com/llvm/llvm-project/commit/9bde15d76dd8d1c93ce7b9b2e25265f57ac3a9f4
DIFF: https://github.com/llvm/llvm-project/commit/9bde15d76dd8d1c93ce7b9b2e25265f57ac3a9f4.diff

LOG: [libc++] Deprecate std::launch::any extension (#173397)

`std::launch::any` was a draft C++11 feature that was removed before the
final standard but it has remained in libc++ as an extension. This patch
marks it as deprecated and suggests using `std::launch::async |
std::launch::deferred` instead.

- Used `_LIBCPP_DEPRECATED_` to mark `std::launch::any` as deprecated
with an associated warning message recommending `std::launch::async |
std::launch::deferred` instead.
- Added a `.verify.cpp` test to validate the deprecation warning.
- Updated existing tests to avoid using the deprecated extension.
- Added note about deprecation in docs.

Fixes #173219

---------

Co-authored-by: Louis Dionne <ldionne.2 at gmail.com>

Added: 
    libcxx/test/libcxx/thread/futures/launch_any_deprecated.verify.cpp

Modified: 
    libcxx/docs/ReleaseNotes/23.rst
    libcxx/include/future
    libcxx/test/libcxx/thread/nodiscard.verify.cpp
    libcxx/test/std/thread/futures/futures.async/async.pass.cpp
    libcxx/test/std/thread/futures/futures.overview/launch.pass.cpp

Removed: 
    


################################################################################
diff  --git a/libcxx/docs/ReleaseNotes/23.rst b/libcxx/docs/ReleaseNotes/23.rst
index bec665c167ce3..c19a731a006d7 100644
--- a/libcxx/docs/ReleaseNotes/23.rst
+++ b/libcxx/docs/ReleaseNotes/23.rst
@@ -46,6 +46,9 @@ Improvements and New Features
 Deprecations and Removals
 -------------------------
 
+- The ``std::launch::any`` enumerator that was accidentally provided as an extension is now deprecated.
+  It will be removed in LLVM 25.
+
 Potentially breaking changes
 ----------------------------
 

diff  --git a/libcxx/include/future b/libcxx/include/future
index 4cd5e8ab2aec8..4084148e52af6 100644
--- a/libcxx/include/future
+++ b/libcxx/include/future
@@ -435,7 +435,12 @@ struct is_error_code_enum<future_errc::__lx> : public true_type {};
 #    endif
 
 // enum class launch
-_LIBCPP_DECLARE_STRONG_ENUM(launch){async = 1, deferred = 2, any = async | deferred};
+_LIBCPP_DECLARE_STRONG_ENUM(launch){
+    async                                                     = 1,
+    deferred                                                  = 2,
+    any _LIBCPP_DEPRECATED_("std::launch::any is a deprecated extension. "
+                            "Use std::launch::async | std::launch::deferred instead. "
+                            "It will be removed in LLVM 25.") = async | deferred};
 _LIBCPP_DECLARE_STRONG_ENUM_EPILOG(launch)
 
 #    ifndef _LIBCPP_CXX03_LANG
@@ -1876,7 +1881,7 @@ async(launch __policy, _Fp&& __f, _Args&&... __args) {
 template <class _Fp, class... _Args>
 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI future<__invoke_result_t<__decay_t<_Fp>, __decay_t<_Args>...> >
 async(_Fp&& __f, _Args&&... __args) {
-  return std::async(launch::any, std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
+  return std::async(launch::async | launch::deferred, std::forward<_Fp>(__f), std::forward<_Args>(__args)...);
 }
 
 #    endif // C++03

diff  --git a/libcxx/test/libcxx/thread/futures/launch_any_deprecated.verify.cpp b/libcxx/test/libcxx/thread/futures/launch_any_deprecated.verify.cpp
new file mode 100644
index 0000000000000..28e02b2c646f0
--- /dev/null
+++ b/libcxx/test/libcxx/thread/futures/launch_any_deprecated.verify.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <future>
+
+// enum class launch;
+
+// Verify that std::launch::any is deprecated.
+// It was a draft C++11 feature that was removed, but libc++ kept it as an extension.
+
+#include <future>
+
+void test() {
+  (void)std::launch::any; // expected-warning {{std::launch::any is a deprecated extension}}
+}

diff  --git a/libcxx/test/libcxx/thread/nodiscard.verify.cpp b/libcxx/test/libcxx/thread/nodiscard.verify.cpp
index fe4c2b091c080..23a7554d3095a 100644
--- a/libcxx/test/libcxx/thread/nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/thread/nodiscard.verify.cpp
@@ -111,7 +111,7 @@ void test() {
       // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
       std::async([]() {});
       // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
-      std::async(std::launch::any, []() {});
+      std::async(std::launch::async | std::launch::deferred, []() {});
     }
 #endif
 

diff  --git a/libcxx/test/std/thread/futures/futures.async/async.pass.cpp b/libcxx/test/std/thread/futures/futures.async/async.pass.cpp
index 81232492c2545..28ca384a37b65 100644
--- a/libcxx/test/std/thread/futures/futures.async/async.pass.cpp
+++ b/libcxx/test/std/thread/futures/futures.async/async.pass.cpp
@@ -114,7 +114,6 @@ int main(int, char**)
     bool DPID = DefaultPolicyIsDeferred;
 
     std::launch AnyPolicy = std::launch::async | std::launch::deferred;
-    LIBCPP_ASSERT(AnyPolicy == std::launch::any);
 
     {
         auto checkInt = [](std::future<int>& f) { return f.get() == 3; };

diff  --git a/libcxx/test/std/thread/futures/futures.overview/launch.pass.cpp b/libcxx/test/std/thread/futures/futures.overview/launch.pass.cpp
index 37ad2ff4a8645..a894a8600676d 100644
--- a/libcxx/test/std/thread/futures/futures.overview/launch.pass.cpp
+++ b/libcxx/test/std/thread/futures/futures.overview/launch.pass.cpp
@@ -14,7 +14,6 @@
 // {
 //     async = 1,
 //     deferred = 2,
-//     any = async | deferred /* EXTENSION */
 // };
 
 #include <future>
@@ -24,22 +23,17 @@
 
 int main(int, char**)
 {
-#if TEST_STD_VER < 11
-   LIBCPP_STATIC_ASSERT(static_cast<int>(std::launch::any) ==
-                 (static_cast<int>(std::launch::async) | static_cast<int>(std::launch::deferred)), "");
-#else
-    LIBCPP_STATIC_ASSERT(std::launch::any == (std::launch::async | std::launch::deferred), "");
-    static_assert(std::launch(0) == (std::launch::async & std::launch::deferred), "");
-    LIBCPP_STATIC_ASSERT(std::launch::any == (std::launch::async ^ std::launch::deferred), "");
-    LIBCPP_STATIC_ASSERT(std::launch::deferred == ~std::launch::async, "");
-    std::launch x = std::launch::async;
-    x &= std::launch::deferred;
-    assert(x == std::launch(0));
-    x = std::launch::async;
-    x |= std::launch::deferred;
-    LIBCPP_ASSERT(x == std::launch::any);
-    x ^= std::launch::deferred;
-    assert(x == std::launch::async);
+#if TEST_STD_VER >= 11
+  static_assert(std::launch(0) == (std::launch::async & std::launch::deferred), "");
+  LIBCPP_STATIC_ASSERT(std::launch::deferred == ~std::launch::async, "");
+  std::launch x = std::launch::async;
+  x &= std::launch::deferred;
+  assert(x == std::launch(0));
+  x = std::launch::async;
+  x |= std::launch::deferred;
+  assert(x == (std::launch::async | std::launch::deferred));
+  x ^= std::launch::deferred;
+  assert(x == std::launch::async);
 #endif
     static_assert(static_cast<int>(std::launch::async) == 1, "");
     static_assert(static_cast<int>(std::launch::deferred) == 2, "");