This patch did not get committed in a timely manner after it was OK'd. In
revisiting the patch some issues were found that have lead me to resubmit
for review -

Specifically -

The original commit to add C++20 atomic_flag::test did not include the free
functions for atomic_flag_test[_explicit]
The original commit to add C++20 atomic_flag::wait/notify did not include
the free functions for atomic_flag_wait/notify[_explicit]

These two commits landed in GCC10 and GCC11 respectively. My original patch
included both sets of free functions, but
that complicates the backporting of these changes to GCC10, GCC11, and
GCC12.

Additionally commit 7c2155 removed const qualification from
atomic_flag::notify_one/notify_all but the original version of this
patch accepts the atomic flag as const.

The original version of this patch did not include test cases for the
atomic_flag_test[_explicit] free functions.

I have split the original patch into two patches, on for the
atomic_flag_test free functions, and one for the atomic_flag_wait/notify
free functions.


On Wed, Feb 2, 2022 at 1:35 PM Jonathan Wakely <jwakely@redhat.com> wrote:

> >+  inline void
> >+  atomic_flag_wait_explicit(const atomic_flag* __a, bool __old,
> >+               std::memory_order __m) noexcept
>
> No need for the std:: qualification, and check the indentation.
>
>
> > libstdc++-v3/ChangeLog:
> >
> >    PR103934
>
> This needs to include the component: PR libstdc++/103934
>
> >    * include/std/atomic: Add missing free functions.
>
> Please name the new functions in the changelog, in the usual format.
> Just the names is fine, no need for the full signatures with
> parameters.
>
> OK for trunk with those changes.
>
>