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From: "manu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/109123] Bogus warning: pointer used after 'realloc'
 -Wuse-after-free with -O2
Date: Tue, 14 Mar 2023 12:51:34 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109123

--- Comment #8 from Manuel L=C3=B3pez-Ib=C3=A1=C3=B1ez <manu at gcc dot gnu=
.org> ---
(In reply to Richard Biener from comment #7)
> Warning for "escapes" (the store is an escape point) is also sensible I
> think.

Would it be possible to make this distinction at the point of warning?=20

> Warning for other uses is really only sensible before any code motion pass
> took place.

Can you move the warning pass before the first code motion pass?=20

Or split it in two warning passes: warning for any uses (before code motion)
and warn for escapes and deref (after code motion)?

> Unfortunately the testsuite is full of cases expected to be diagnosed but
> are no longer with any change to the operation.

It is better to miss some warnings rather than warn too much because otherw=
ise
users will use any means available to silence them (often -Wno-use-after-fr=
ee)
and the useful warnings will be lost.

For comprehensive code analysis, users should look at the static analyzer.=