Committed to trunk, backported to releases/gcc-11. On Fri, Feb 11, 2022 at 12:22 PM Jonathan Wakely <jwak...@redhat.com> wrote:
> On Fri, 11 Feb 2022 at 17:40, Thomas Rodgers via Libstdc++ > <libstd...@gcc.gnu.org> wrote: > > > > <recording this here for future reference> > > PR102994 "atomics: std::atomic<ptr>::wait is not marked const" raises the > > issue that the current libstdc++ implementation marks the notify members > > const, the implementation strategy used by libstdc++, as well as libc++ > > and the Microsoft STL, do not require the atomic to be mutable (it is > hard > > to conceive of a desirable implementation approach that would require > it). > > The original paper proposing the wait/notify functionality for atomics > > (p1185) also had these members marked const for the first three > revisions, > > but that was changed without explanation in r3 and subsequent revisions > of > > the paper. > > > > After raising the issue to the authors of p1185 and the author of the > > libc++ implementation, the consensus seems to be "meh, it's harmless" so > > there seems little appetite for an LWG issue to revisit the subject. > > > > This patch changes the libstdc++ implementation to be in agreement with > > the standard by removing const from those notify_one/notify_all members. > > > > libstdc++-v3/ChangeLog: > > Might as well add a "PR libstdc++/102994" here to the bug gets updated > automatically. > > OK for trunk with that change. > > > * include/bits/atomic_base.h (atomic_flag::notify_one, > > notify_all): Remove const qualification. > > (__atomic_base::notify_one, notify_all): Likewise. > > * include/std/atomic (atomic<bool>::notify_one, notify_all): > > Likewise. > > (atomic::notify_one, notify_all): Likewise. > > (atomic<T*>::notify_one, notify_all): Likewise. > > (atomic_notify_one, atomic_notify_all): Likewise. > > * testsuite/29_atomics/atomic/wait_notify/102994.cc: Adjust test > > to account for change in notify_one/notify_all signature. > > > > Tested x86_64-pc-linux-gnu. > >
