From c2b74fd7cf2668d288f46da42565e5eb954e5e1f Mon Sep 17 00:00:00 2001
From: Thomas Rodgers <rodgert@twrodgers.com>
Date: Fri, 14 Jan 2022 18:30:27 -0800
Subject: [PATCH] libstdc++: Add missing free functions for atomic_flag
 [PR103934]

libstdc++-v3/ChangeLog:

	PR103934
	* include/std/atomic: Add missing free functions.
	* testsuite/29_atomics/atomic_flag/wait_notify/1.cc:
	Add test case to cover missing atomic_flag free functions.
---
 libstdc++-v3/include/std/atomic               | 39 +++++++++++++++++++
 .../29_atomics/atomic_flag/wait_notify/1.cc   | 27 +++++++++++--
 2 files changed, 63 insertions(+), 3 deletions(-)

diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index 9df17704f7e..92c96a9b047 100644
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -1216,6 +1216,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 				    memory_order __m) noexcept
   { return __a->test_and_set(__m); }
 
+#if __cpp_lib_atomic_flag_test
+  inline bool
+  atomic_flag_test(const atomic_flag* __a) noexcept
+  { return __a->test(); }
+
+  inline bool
+  atomic_flag_test(const volatile atomic_flag* __a) noexcept
+  { return __a->test(); }
+
+  inline bool
+  atomic_flag_test_explicit(const atomic_flag* __a,
+			    memory_order __m) noexcept
+  { return __a->test(__m); }
+
+  inline bool
+  atomic_flag_test_explicit(const volatile atomic_flag* __a,
+			    memory_order __m) noexcept
+  { return __a->test(__m); }
+#endif
+
   inline void
   atomic_flag_clear_explicit(atomic_flag* __a, memory_order __m) noexcept
   { __a->clear(__m); }
@@ -1241,6 +1261,25 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   atomic_flag_clear(volatile atomic_flag* __a) noexcept
   { atomic_flag_clear_explicit(__a, memory_order_seq_cst); }
 
+#if __cpp_lib_atomic_wait
+  inline void
+  atomic_flag_wait(const atomic_flag* __a, bool __old) noexcept
+  { __a->wait(__old); }
+
+  inline void
+  atomic_flag_wait_explicit(const atomic_flag* __a, bool __old,
+		       std::memory_order __m) noexcept
+  { __a->wait(__old, __m); }
+
+  inline void
+  atomic_flag_notify_one(const atomic_flag* __a) noexcept
+  { __a->notify_one(); }
+
+  inline void
+  atomic_flag_notify_all(const atomic_flag* __a) noexcept
+  { __a->notify_all(); }
+#endif // __cpp_lib_atomic_wait
+
 
   template<typename _Tp>
     using __atomic_val_t = typename atomic<_Tp>::value_type;
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_flag/wait_notify/1.cc b/libstdc++-v3/testsuite/29_atomics/atomic_flag/wait_notify/1.cc
index 87a104059ff..1050b72a1c6 100644
--- a/libstdc++-v3/testsuite/29_atomics/atomic_flag/wait_notify/1.cc
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_flag/wait_notify/1.cc
@@ -26,8 +26,8 @@
 
 #include <testsuite_hooks.h>
 
-int
-main()
+void
+test01()
 {
   std::atomic_flag a;
   VERIFY( !a.test() );
@@ -39,5 +39,26 @@ main()
     });
   a.wait(false);
   t.join();
-  return 0;
+}
+
+void
+test02()
+{
+  std::atomic_flag a;
+  VERIFY( !std::atomic_flag_test(&a) );
+  std::atomic_flag_wait(&a, true);
+  std::thread t([&]
+    {
+      std::atomic_flag_test_and_set(&a);
+      std::atomic_flag_notify_one(&a);
+    });
+  std::atomic_flag_wait(&a, false);
+  t.join();
+}
+
+int
+main()
+{
+  test01();
+  test02();
 }
-- 
2.31.1