1 files changed, 51 insertions, 0 deletions

diff --git a/contrib/libc++/src/mutex_destructor.cpp b/contrib/libc++/src/mutex_destructor.cpp
new file mode 100644
index 000000000000..3a6b6b55eeb7
--- /dev/null
+++ b/contrib/libc++/src/mutex_destructor.cpp
@@ -0,0 +1,51 @@
+//===--------------------- mutex_destructor.cpp ---------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// Define ~mutex.
+//
+// On some platforms ~mutex has been made trivial and the definition is only
+// provided for ABI compatibility.
+//
+// In order to avoid ODR violations within libc++ itself, we need to ensure
+// that *nothing* sees the non-trivial mutex declaration. For this reason
+// we re-declare the entire class in this file instead of using
+// _LIBCPP_BUILDING_LIBRARY to change the definition in the headers.
+
+#include "__config"
+#include "__threading_support"
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#if _LIBCPP_ABI_VERSION == 1 || !defined(_LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION)
+#define NEEDS_MUTEX_DESTRUCTOR
+#endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef NEEDS_MUTEX_DESTRUCTOR
+class _LIBCPP_TYPE_VIS mutex
+{
+    __libcpp_mutex_t __m_ = _LIBCPP_MUTEX_INITIALIZER;
+
+public:
+    _LIBCPP_ALWAYS_INLINE _LIBCPP_INLINE_VISIBILITY
+    constexpr mutex() = default;
+    mutex(const mutex&) = delete;
+    mutex& operator=(const mutex&) = delete;
+    ~mutex() noexcept;
+};
+
+
+mutex::~mutex() _NOEXCEPT
+{
+    __libcpp_mutex_destroy(&__m_);
+}
+
+#endif // !_LIBCPP_HAS_NO_THREADS
+_LIBCPP_END_NAMESPACE_STD
+