Re: [PATCH] Avoid allocator operator== in _Safe_container

[Jonathan Wakely <jwakely@redhat.com>]

On Mon, 9 Aug 2021 at 13:08, François Dumont <frs.dumont@gmail.com> wrote:
>
> On 09/08/21 1:52 pm, François Dumont wrote:
> > On 09/08/21 12:45 pm, Jonathan Wakely wrote:
> >> On Mon, 9 Aug 2021 at 11:34, Jonathan Wakely wrote:
> >>> On Mon, 9 Aug 2021 at 11:33, Jonathan Wakely wrote:
> >>>> On Mon, 9 Aug 2021 at 11:26, François Dumont via Libstdc++
> >>>> <libstdc++@gcc.gnu.org> wrote:
> >>>>> Some newly introduced tests in
> >>>>> 23_containers/unordered_map/cons/default.cc revealed that we are
> >>>>> forcing
> >>>>> the allocator type to have a operator==.
> >>>> All allocators are required to have operator== so that should not be a
> >>>> problem. What is the error?
> >>> OK, I see it. I just forgot to define operator== and operator!= for
> >>> the custom allocator in that new test, and that should be added.
> >> Fixed like this instead. Tested x86_64-linux with -D_GLIBCXX_DEBUG.
> >> Pushed to trunk.
> >
> > Ok, I thought my change was better because we have many allocator
> > types in tests without operator ==/!= (see
> > 23_containers/*/cons/noexcept_default_construct.cc). But of course the
> > tests are not making any use of it for the moment, no big deal.

Those tests are all OK, the allocators inherit from std::allocator so
can use its equality operators.

But if I did mess up any more test allocators then we should fix those ones too.

> > So this patch is just an optimization, may I still commit it ? Unless
> > you like the fact that Debug mode is checking that those operators are
> > provided when allocator-aware move constructor is being used.
> >
> >
> A simpler version, using _Safe_container move constructor when allocator
> instances are always equals.

Yes, this optimization is good. OK for trunk, thanks!