[libcxx-commits] [libcxx] c4953a0 - [libc++][NFC] Move checks whether mutex/condition_variable are trivial to their headers (#236806)

[via libcxx-commits]

Author: Nikolas Klauser
Date: 2026-10-30T14:11:31+01:00
New Revision: c4953a08cd91b86c4f02e9380f43483c8bffcd2b

URL: https://github.com/llvm/llvm-project/commit/c4953a08cd91b86c4f02e9380f43483c8bffcd2b
DIFF: https://github.com/llvm/llvm-project/commit/c4953a08cd91b86c4f02e9380f43483c8bffcd2b.diff

LOG: [libc++][NFC] Move checks whether mutex/condition_variable are trivial to their headers (#236806)

The moved macros are only used as implementation details of `mutex` and
`condition_variable` aren't used widely within the library, so they can
be moved to be more local.

Added: 
    

Modified: 
    libcxx/include/__condition_variable/condition_variable.h
    libcxx/include/__config
    libcxx/include/__mutex/mutex.h

Removed: 
    


################################################################################
diff  --git a/libcxx/include/__condition_variable/condition_variable.h b/libcxx/include/__condition_variable/condition_variable.h
index 0e1e811d987679..ab3cbdf5711e15 100644
--- a/libcxx/include/__condition_variable/condition_variable.h
+++ b/libcxx/include/__condition_variable/condition_variable.h
@@ -100,6 +100,20 @@ chrono::steady_clock::time_point __rel_to_abs(const _Duration& __rel_time) {
   return chrono::steady_clock::now() + chrono::__ceil<chrono::steady_clock::duration>(__rel_time);
 }
 
+// Destroying a condvar is a nop on Windows.
+//
+// This optimization can't be performed on Apple platforms, where
+// pthread_cond_destroy can allow the kernel to release resources.
+// See https://llvm.org/D64298 for details.
+//
+// TODO(EricWF): This is potentially true for some pthread implementations
+// as well.
+#  if (_LIBCPP_HAS_THREAD_API_C11 && defined(__Fuchsia__)) || _LIBCPP_HAS_THREAD_API_WIN32
+#    define _LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION 1
+#  else
+#    define _LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION 0
+#  endif
+
 class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_WARN_UNUSED condition_variable {
   __libcpp_condvar_t __cv_ = _LIBCPP_CONDVAR_INITIALIZER;
 

diff  --git a/libcxx/include/__config b/libcxx/include/__config
index ade43d42dc283d..635999f8101745 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -230,38 +230,6 @@ typedef __char32_t char32_t;
 #    define __STDCPP_THREADS__ 1
 #  endif
 
-// The glibc and Bionic implementation of pthreads implements
-// pthread_mutex_destroy as nop for regular mutexes. Additionally, Win32
-// mutexes have no destroy mechanism.
-//
-// This optimization can't be performed on Apple platforms, where
-// pthread_mutex_destroy can allow the kernel to release resources.
-// See https://llvm.org/D64298 for details.
-//
-// clang-format off
-#  if (_LIBCPP_HAS_THREAD_API_PTHREAD && (defined(__GLIBC__) || defined(__BIONIC__))) ||                                \
-      (_LIBCPP_HAS_THREAD_API_C11 && defined(__Fuchsia__)) ||                                                          \
-       _LIBCPP_HAS_THREAD_API_WIN32
-// clang-format on
-#    define _LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION 1
-#  else
-#    define _LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION 0
-#  endif
-
-// Destroying a condvar is a nop on Windows.
-//
-// This optimization can't be performed on Apple platforms, where
-// pthread_cond_destroy can allow the kernel to release resources.
-// See https://llvm.org/D64298 for details.
-//
-// TODO(EricWF): This is potentially true for some pthread implementations
-// as well.
-#  if (_LIBCPP_HAS_THREAD_API_C11 && defined(__Fuchsia__)) || _LIBCPP_HAS_THREAD_API_WIN32
-#    define _LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION 1
-#  else
-#    define _LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION 0
-#  endif
-
 // We often repeat things just for handling wide characters in the library.
 // When wide characters are disabled, it can be useful to have a quick way of
 // disabling it without having to resort to #if-#endif, which has a larger

diff  --git a/libcxx/include/__mutex/mutex.h b/libcxx/include/__mutex/mutex.h
index 699783ec7929d6..e559997489436d 100644
--- a/libcxx/include/__mutex/mutex.h
+++ b/libcxx/include/__mutex/mutex.h
@@ -22,6 +22,24 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
+// The glibc and Bionic implementation of pthreads implements
+// pthread_mutex_destroy as nop for regular mutexes. Additionally, Win32
+// mutexes have no destroy mechanism.
+//
+// This optimization can't be performed on Apple platforms, where
+// pthread_mutex_destroy can allow the kernel to release resources.
+// See https://llvm.org/D64298 for details.
+//
+// clang-format off
+#  if (_LIBCPP_HAS_THREAD_API_PTHREAD && (defined(__GLIBC__) || defined(__BIONIC__))) ||                                \
+      (_LIBCPP_HAS_THREAD_API_C11 && defined(__Fuchsia__)) ||                                                          \
+       _LIBCPP_HAS_THREAD_API_WIN32
+// clang-format on
+#    define _LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION 1
+#  else
+#    define _LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION 0
+#  endif
+
 class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_CAPABILITY("mutex") _LIBCPP_WARN_UNUSED mutex {
   __libcpp_mutex_t __m_ = _LIBCPP_MUTEX_INITIALIZER;