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From: "mpolacek at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/107532] [13 Regression] -Werror=dangling-reference false
 positives in libcamera-0.0.1
Date: Mon, 13 Mar 2023 15:53:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107532

--- Comment #23 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to Kohei Takahashi from comment #21)
> (In reply to Marek Polacek from comment #18)
> > (In reply to Barnab=C3=A1s P=C5=91cze from comment #17)
> > > The simple test case with std::span still triggers the warning:
> > > https://gcc.godbolt.org/z/43cKxdqr3. I feel that without deeper code
> > > analysis such a warning will generate too many false positives and pe=
ople
> > > will simply turn it off.
> >=20
> > There really haven't been that many, except this and one with range-bas=
ed
> > for loops.
>=20
> I think it warns many usage of zip_iterator idiom such as boost.iterator =
and
> P2321 style flat_map. Those uses tuple of references like std::tuple<T&..=
.>
> by dereferencing iterator, so that any algorithms may yield this warning.

Ah, would you please have a testcase?  If that's the case and the warning c=
an't
be taught to recognize that pattern, then I think we need to move it to
-Wextra.  Thanks.=