https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118757
Tomasz Kamiński <tkaminsk at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |tkaminsk at gcc dot gnu.org
--- Comment #2 from Tomasz Kamiński <tkaminsk at gcc dot gnu.org> ---
I am looking at https://eel.is/c++draft/atomics.wait#4 that defines what waits
are eligle for notication:
4 A call to an atomic waiting operation on an atomic object M is eligible to be
unblocked by a call to an atomic notifying operation on M if there exist side
effects X and Y on M such that:
(4.1)
the atomic waiting operation has blocked after observing the result of X,
(4.2)
X precedes Y in the modification order of M, and
(4.3)
Y happens before the call to the atomic notifying operation.
The `p.store({ q, nullptr });` seem to be good candidate to producing side
effect of Y, however there is no side effect `X` that `p.wait(q)` is observing.
In particular construction is not atomic operator per
https://eel.is/c++draft/util.smartptr.atomic#shared-2:
> Effects: Initializes the object with the value desired. Initialization is not
> an atomic operation ([intro.multithread]).
