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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libstdc++/104719] Use of `std::move` in libstdc++ leads to
 worsened debug performance
Date: Mon, 28 Feb 2022 17:16:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104719

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|https://gcc.gnu.org/bugzill |
                   |a/show_bug.cgi?id=3D67906,    |
                   |https://gcc.gnu.org/bugzill |
                   |a/show_bug.cgi?id=3D81159,    |
                   |https://gcc.gnu.org/bugzill |
                   |a/show_bug.cgi?id=3D90428     |

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #3)
> Seems related to some of the requests for more warnings about uses of
> std::move that might degrade performance, e.g. bug 67906, bug 81159, bug
> 90428
>=20
> Also, Marek's blog post about std::move seems relevant here:
> https://developers.redhat.com/blog/2019/04/12/understanding-when-not-to-
> stdmove-in-c

I don't think any of those are relevant, they're about *unnecessary* uses of
std::move where that is either entirely redundant or doesn't change semanti=
cs
but prevents the optimizer doing better on its own. This is about *necessar=
y*
uses of std::move, and removing the move here would change semantics and
potentially break the code. The request is to replace it with some kind of
magic that does the same as std::move without actually writing std::move.=