From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id B66253857012; Sat, 27 Aug 2022 07:17:18 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B66253857012
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1661584638;
	bh=plTz54s+Q6RzS255iGb5IH3trUREIdaS/zPHTFj/tP4=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=KQ01UHGvNmuEvi7gg8pUeUzHNZmxkxW2rcAAWgqTCBWAJI7Skkxikp9kzd1HDoEmN
	 rh4Vb/fLD+Wnb+3qrdiAjjSvhjR0X4dESkJeTj3GZNGwR3Ypjb9f4D0DSU7inD/aCS
	 F85PADbdVu6DbgfxDav5z6zvBP0Vy554q+g5W2K4=
From: "simon at josefsson dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/106427] -Wuse-after-free=3 false alarm about int
 (not pointer) variable
Date: Sat, 27 Aug 2022 07:17:18 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 12.1.1
X-Bugzilla-Keywords: diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: simon at josefsson dot org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: cc
Message-ID: <bug-106427-4-Nf9yXXj4aq@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-106427-4@http.gcc.gnu.org/bugzilla/>
References: <bug-106427-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106427

Simon Josefsson <simon at josefsson dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simon at josefsson dot org

--- Comment #1 from Simon Josefsson <simon at josefsson dot org> ---
I ran into this problem too, here is a simple reproducer:

$ gcc -Werror -Wuse-after-free=3D3 -g -O2 -o foo foo.c
foo.c: In function 'main':
foo.c:18:6: error: pointer may be used after 'free' [-Werror=3Duse-after-fr=
ee]
   18 |   if (strstr (in, "FOO"))
      |      ^
foo.c:21:3: note: call to 'free' here
   21 |   free (in);
      |   ^~~~~~~~~
cc1: all warnings being treated as errors

#include <string.h>
#include <stdlib.h>

extern int readln (char **out);

int
main (void)
{
  char *in =3D NULL;
  int i =3D 0;

  if (!readln (&in))
    return 0;

  if (in =3D=3D NULL)
    return 0;

  if (strstr (in, "FOO"))
    i =3D 1;

  free (in);
  in =3D NULL;

  if (!readln (&in))
    return 0;

  if (in =3D=3D NULL)
    return 0;

  free (in);

  return i;
}=