[libcxx-commits] [libcxx] [libcxx] LWG4172 fix self-move-assignment in {unique|shared}_lock (PR #129542)

[A. Jiang via libcxx-commits]

================
@@ -74,13 +74,7 @@ class unique_lock {
   }
 
   _LIBCPP_HIDE_FROM_ABI unique_lock& operator=(unique_lock&& __u) _NOEXCEPT {
-    if (__owns_)
-      __m_->unlock();
-
-    __m_        = __u.__m_;
-    __owns_     = __u.__owns_;
-    __u.__m_    = nullptr;
-    __u.__owns_ = false;
+    unique_lock{std::move(__u)}.swap(*this);
----------------
frederick-vs-ja wrote:

You should include `<__utility/move.h>` in `<__mutex/unique_lock.h>` and `<shared_mutex>`. And then you need to add

```C++
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
```
immediately before
```C++
_LIBCPP_BEGIN_NAMESPACE_STD
```

, and

```C++
_LIBCPP_POP_MACROS
```
immediately after
```C++
_LIBCPP_END_NAMESPACE_STD
```

https://github.com/llvm/llvm-project/pull/129542