[libcxx-commits] [libcxx] [libc++] Always use uintptr_t as the state type of once_flag (PR #220603)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 created https://github.com/llvm/llvm-project/pull/220603

None

>From a51d1fcc898b707226a786d379b18ef542e9d7f2 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Wed, 2 Sep 2026 16:19:12 +0200
Subject: [PATCH] [libc++] Always use uintptr_t as the state type of once_flag

---
 libcxx/include/__mutex/once_flag.h | 16 +++++-----------
 libcxx/src/call_once.cpp           |  2 +-
 2 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/libcxx/include/__mutex/once_flag.h b/libcxx/include/__mutex/once_flag.h
index 63c97a2921412..c1051d4806800 100644
--- a/libcxx/include/__mutex/once_flag.h
+++ b/libcxx/include/__mutex/once_flag.h
@@ -52,18 +52,12 @@ struct once_flag {
   once_flag(const once_flag&)            = delete;
   once_flag& operator=(const once_flag&) = delete;
 
-#ifdef _WIN32
-  typedef uintptr_t _State_type;
-#else
-  typedef unsigned long _State_type;
-#endif
-
-  static const _State_type _Unset    = 0;
-  static const _State_type _Pending  = 1;
-  static const _State_type _Complete = ~_State_type(0);
+  static const uintptr_t _Unset    = 0;
+  static const uintptr_t _Pending  = 1;
+  static const uintptr_t _Complete = ~uintptr_t(0);
 
 private:
-  _State_type __state_;
+  uintptr_t __state_;
 
 #ifndef _LIBCPP_CXX03_LANG
   template <class _Callable, class... _Args>
@@ -114,7 +108,7 @@ void _LIBCPP_HIDE_FROM_ABI __call_once_proxy(void* __vp) {
 }
 
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
-_LIBCPP_EXPORTED_FROM_ABI void __call_once(volatile once_flag::_State_type&, void*, void (*)(void*));
+_LIBCPP_EXPORTED_FROM_ABI void __call_once(volatile uintptr_t&, void*, void (*)(void*));
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 
 template <class _ValueType>
diff --git a/libcxx/src/call_once.cpp b/libcxx/src/call_once.cpp
index 015b874cffa44..3f410871669d6 100644
--- a/libcxx/src/call_once.cpp
+++ b/libcxx/src/call_once.cpp
@@ -30,7 +30,7 @@ static constinit __libcpp_mutex_t mut  = _LIBCPP_MUTEX_INITIALIZER;
 static constinit __libcpp_condvar_t cv = _LIBCPP_CONDVAR_INITIALIZER;
 #endif
 
-void __call_once(volatile once_flag::_State_type& flag, void* arg, void (*func)(void*)) {
+void __call_once(volatile uintptr_t& flag, void* arg, void (*func)(void*)) {
 #if !_LIBCPP_HAS_THREADS
 
   if (flag == once_flag::_Unset) {