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 B93363858D38; Tue, 11 Apr 2023 08:25:32 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B93363858D38
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1681201532;
	bh=/01foxTJjqofMxr8aem8RH5ReNjxO51uulUj0Su0Qyk=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=NF9uDhmLXgO4sTcr1Wj1nTD5oVHbDuT0LDOeD6T4HTeGSvHbk+47Lu0n96atbjOuC
	 XOMBlgtl2dDOtJTkh3TarEJjkO3FnKEU0lB9vVUoyraEPh7bbECcEAiRzGBazGx52H
	 v/+xH90b0GdC/mkkmaYkV42AWqZnyzTKlogU1LsE=
From: "xry111 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/109470] unexpected const & behavior
Date: Tue, 11 Apr 2023 08:25:32 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: xry111 at gcc dot gnu.org
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: INVALID
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 resolution bug_status
Message-ID: <bug-109470-4-EmEiYU2jKB@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109470-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109470-4@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=3D109470

Xi Ruoyao <xry111 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xry111 at gcc dot gnu.org
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #1 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
The standard says:

A temporary object bound to a reference parameter in a function call persis=
ts
until the completion of the full-expression containing the call.

So at the "assert" line the lifetime of the temporary object created by the
prvalue to glvalue materialization of (int)lenght has already ended.  Any
reference to the temporary is dangling and it's undefined behavior to use s=
uch
a reference.=