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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/108165] -Wdangling-reference false positive
Date: Wed, 01 Feb 2023 18:14:12 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108165

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #5)
> Sorry, I'm not sure if the false positive in comment 0 can be fixed.  I
> can't simply compare the type of the temporary argument and the return ty=
pe,
> because we may be returning a subobject of the temporary argument, which =
is
> still dangerous.

Well, you could e.g. walk recursively all the TYPE_FIELDS of the type of the
temporary
and compare to the type the return type references.  If the temporary has s=
ome
subobject of that type or if the temporary itself has that type, warn,
otherwise not warn.
There would still be false positives and false negatives, but those are wit=
hout
actually looking at the definition unavoidable.=