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 93FE13858CDB; Wed, 21 Sep 2022 17:51:12 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 93FE13858CDB
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1663782672;
	bh=yF86AUXEf3bt9ybb0uI8c8KcshXTw2f1vB3N0DHY9lo=;
	h=From:To:Subject:Date:From;
	b=s5Lx5kxz+pCqAs6u0C1/3VJM6OKMoM0UT9E1BHe/rUhqlz+G32UJPoqbFf8ue80u/
	 sDiWKEzJyuUDEdydtbl44XdD5WkWQAqEGDfvJJ+OFrBV/QXpeVsmEx1Y96igPTrXCe
	 7fihZWc66TuyXNYVAwG8ew4O+E1XhRYn/FtQZHqQ=
From: "rogerio.souza at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107004] New: GCC12 warning in OOB access:
 array subscript is partly outside array bounds
Date: Wed, 21 Sep 2022 17:51:12 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 12.2.0
X-Bugzilla-Keywords: TREE
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rogerio.souza at gmail dot com
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: bug_id short_desc product version bug_file_loc
 bug_status keywords bug_severity priority component assigned_to reporter
 target_milestone
Message-ID: <bug-107004-4@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=3D107004

            Bug ID: 107004
           Summary: GCC12 warning in OOB access: array subscript is partly
                    outside array bounds
           Product: gcc
           Version: 12.2.0
               URL: https://godbolt.org/z/aoYh66EYb
            Status: UNCONFIRMED
          Keywords: TREE
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rogerio.souza at gmail dot com
  Target Milestone: ---

The code below triggers the warning:

/opt/compiler-explorer/gcc-12.2.0/include/c++/12.2.0/bits/stl_construct.h:1=
19:7:
warning: array subscript 'int*[0]' is partly outside array bounds of 'unsig=
ned
char [8]' [-Warray-bounds]
  119 |       ::new((void*)__p) _Tp(std::forward<_Args>(__args)...);
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Source code:

#include <vector>
#include <cassert>

void foo(std::vector<int*>& v)
{
    assert(v.size() >=3D 1);
    v.resize(1);
}

Build command line:
g++ -std=3Dc++20 -Wall -Wextra -pedantic -O3

Using -O2 prevents the warning, also if we use "-Wno-array-bounds". This is=
sue
is not reproducible on GCC 11.3 or older.

Would this issue be a duplicate from
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105348?

The issue could be reproduced on Compiler Explorer:
https://godbolt.org/z/aoYh66EYb

Regards,
Rogerio=