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 AA9DA3850874; Tue, 28 Mar 2023 23:35:12 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org AA9DA3850874
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1680046512;
	bh=DO0zj51m4y11po5303fgbcW/tkS4QCJhnUk25O6zrRo=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=PKli6NoZdWndiVCjU551DvZjPFv9dZvgwSzF6lCFC/W8P3/pEQuu6pkOd854IZ2ua
	 TT0OTv3vz1NzkXwxKx32rBua/KXFEKJgYZXwRyw6Musuxt2ujC3uNfD4gMv2SxjULb
	 xHX/sA8aut/FyAG6u8r2o3GoahxhMwsoEFjixn2w=
From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/108554] [12 Regression] Warning "null pointer
 dereferece" raised when extracting a unique_ptr from a map and any "-O" flag
Date: Tue, 28 Mar 2023 23:35:11 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 12.2.0
X-Bugzilla-Keywords: diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: cvs-commit at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: redi at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 12.3
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-108554-4-yL6se7Uey8@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-108554-4@http.gcc.gnu.org/bugzilla/>
References: <bug-108554-4@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=3D108554

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:2fdfa3768b25c85df39eaf9b850e130e42a4dd6f

commit r12-9345-g2fdfa3768b25c85df39eaf9b850e130e42a4dd6f
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Jan 26 10:55:28 2023 +0000

    libstdc++: Add returns_nonnull to non-inline std::map detail [PR108554]

    std::map uses a non-inline function to rebalance its tree and the
    compiler can't see that it always returns a valid pointer (assuming
    valid inputs, which is a precondition anyway). This can result in
    -Wnull-derefernce warnings for valid code, because the compiler thinks
    there is a path where the function returns null.

    Adding the returns_nonnull attribute tells the compiler that is can't
    happen. While we're doing that, we might as well also add a nonnull
    attribute to the rebalancing functions too.

    libstdc++-v3/ChangeLog:

            PR libstdc++/108554
            * include/bits/stl_tree.h (_Rb_tree_insert_and_rebalance): Add
            nonnull attribute.
            (_Rb_tree_rebalance_for_erase): Add nonnull and returns_nonnull
            attributes.
            * testsuite/23_containers/map/modifiers/108554.cc: New test.

    (cherry picked from commit 3376467ce090aa0966d59ca3aea35db4f17a4b47)=