[gcc r12-9238] libstdc++: Add missing free functions for atomic_flag [PR103934]

[gcc r12-9238] libstdc++: Add missing free functions for atomic_flag [PR103934]

[Thomas Rodgers]

https://gcc.gnu.org/g:1784d252cecb0c8f4025ee587af4c29cc0992923

commit r12-9238-g1784d252cecb0c8f4025ee587af4c29cc0992923
Author: Thomas W Rodgers <rodgert@twrodgers.com>
Date:   Fri Feb 10 10:09:06 2023 -0800

    libstdc++: Add missing free functions for atomic_flag [PR103934]
    
    This patch adds -
      atomic_flag_wait
      atomic_flag_wait_explicit
      atomic_flag_notify
      atomic_flag_notify_explicit
    
    Which were missed when commit 83a1be introduced C++20 atomic wait.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/103934
            * include/std/atomic (atomic_flag_wait): Add.
            (atomic_flag_wait_explicit): Add.
            (atomic_flag_notify): Add.
            (atomic_flag_notify_explicit): Add.
            * testsuite/29_atomics/atomic_flag/wait_notify/1.cc:
            Add test case to cover missing atomic_flag free functions.
    
    (cherry picked from commit 56cf9372c0596c4df4003c72dc4665a306fbfe31)

Diff:
---
 libstdc++-v3/include/std/atomic                    | 24 ++++++++++++++++++--
 .../29_atomics/atomic_flag/wait_notify/1.cc        | 26 ++++++++++++++++++++--
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index 9e042d8ce44..faf7eb95594 100644
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -388,7 +388,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { return compare_exchange_strong(__e, __i, __m,
                                        __cmpexch_failure_order(__m)); }
 
-#if __cpp_lib_atomic_wait 
+#if __cpp_lib_atomic_wait
     void
     wait(_Tp __old, memory_order __m = memory_order_seq_cst) const noexcept
     {
@@ -405,7 +405,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     void
     notify_all() noexcept
     { std::__atomic_notify_address(&_M_i, true); }
-#endif // __cpp_lib_atomic_wait 
+#endif // __cpp_lib_atomic_wait
 
     };
 #undef _GLIBCXX20_INIT
@@ -1261,6 +1261,26 @@ _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(atomic_flag* __a, bool __old) noexcept
+  { __a->wait(__old); }
+
+  inline void
+  atomic_flag_wait_explicit(atomic_flag* __a, bool __old,
+                                memory_order __m) noexcept
+  { __a->wait(__old, __m); }
+
+  inline void
+  atomic_flag_notify_one(atomic_flag* __a) noexcept
+  { __a->notify_one(); }
+
+  inline void
+  atomic_flag_notify_all(atomic_flag* __a) noexcept
+  { __a->notify_all(); }
+#endif // __cpp_lib_atomic_wait
+
+  /// @cond undocumented
   // _GLIBCXX_RESOLVE_LIB_DEFECTS
   // 3220. P0558 broke conforming C++14 uses of atomic shared_ptr
   template<typename _Tp>
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..dbd34609049 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 +39,27 @@ main()
     });
   a.wait(false);
   t.join();
+}
+
+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();
   return 0;
 }