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From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 20 Oct 2021 09:42:29 +0100
Message-ID: <CACb0b4nBpiY9youtM40_TEHWQUjcqytomCQFWZC4hUTwSsm7cg@mail.gmail.com>
Subject: Re: [committed] libstdc++: Implement monadic operations for
 std::optional (P0798R8)
To: Tim Song <t.canens.cpp@gmail.com>
Cc: "libstdc++" <libstdc++@gcc.gnu.org>, gcc-patches <gcc-patches@gcc.gnu.org>
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On Wed, 20 Oct 2021 at 06:48, Tim Song wrote:
>
> On Tue, Oct 19, 2021 at 9:05 AM Jonathan Wakely via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > +constexpr bool
> > +test_copy_elision()
> > +{
> > +  return true;
> > +}
> > +
> > +static_assert( test_copy_elision() );
> > +
>
> This isn't much of a test :)

The ultimate copy elision. The copies even get removed from the source code.

Thanks for spotting it. I meant to check we're constructing directly
into the union member without materializing the temporary early. I'll
add that today.