[libcxx-commits] [libcxx] [libc++] fix `counting_semaphore` lost wakeups (PR #79265)

[Louis Dionne via libcxx-commits]

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@@ -62,9 +62,17 @@ struct __libcpp_atomic_wait_backoff_impl {
   }
 };
 
+template <class _Atp, class _Fn, class _Fn2>
+_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool
+__cxx_atomic_wait(_Atp* __a, _Fn&& __test_fn, _Fn2&& __test_with_old) {
+  __libcpp_atomic_wait_backoff_impl<_Atp, __decay_t<_Fn2> > __backoff_fn = {__a, __test_with_old};
+  return std::__libcpp_thread_poll_with_backoff(__test_fn, __backoff_fn);
+}
+
 template <class _Atp, class _Fn>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool __cxx_atomic_wait(_Atp* __a, _Fn&& __test_fn) {
-  __libcpp_atomic_wait_backoff_impl<_Atp, __decay_t<_Fn> > __backoff_fn = {__a, __test_fn};
+  auto __test_with_old = [&](auto&) { return __test_fn(); };
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ldionne wrote:

I think you need to use a struct here cause it seems this header needs to work in C++03 mode.

https://github.com/llvm/llvm-project/pull/79265