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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libstdc++/97936] [11 Regression] 30_threads/latch/3.cc hangs
Date: Wed, 25 Nov 2020 01:30:12 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97936

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #1)
> Also:
>=20
> FAIL: 29_atomics/atomic_integral/wait_notify.cc

This looks like a bug in the test:

  std::atomic<Tp> a(val1);
  std::thread t([&]
                {
                  cv.notify_one();
                  a.wait(val1);
                  if (a.load() !=3D val2)
                    a =3D val1;
                });
  std::unique_lock<std::mutex> l(m);
  cv.wait(l);


The new thread might run cv.notify_one() before cv.wait(l) so we get a miss=
ed
notification and block forever.=