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 735E03858D1E; Wed, 21 Dec 2022 11:03:16 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 735E03858D1E
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1671620596;
	bh=t1b++VRPKwEUCKguoKSWpRvMH56iFskt3DE6B8N3Xic=;
	h=From:To:Subject:Date:From;
	b=Y6PIiDj02Ad1wB1Wf9NqtAJQom6+RQ+YD4IigBDsAc6r9dug+tjPN8ipGDpSPtU5e
	 rJ9t9UqmHj7gInK2bWl6kxfCdHnGsdsx+jqODe26M+iAfWWun2qCWtWeTJSUKlOm/C
	 dAeye1WaOPusXcR4DXrxCFiFvDmu4UqTqFifAJOw=
From: "pskocik at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/108194] New: GCC won't treat two compatible function types as
 compatible if any of them (or both of them) is declared _Noreturn
Date: Wed, 21 Dec 2022 11:03:16 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
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: pskocik 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_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-108194-4@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=3D108194

            Bug ID: 108194
           Summary: GCC won't treat two compatible function types as
                    compatible if any of them (or both of them) is
                    declared _Noreturn
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pskocik at gmail dot com
  Target Milestone: ---

(same with __attribute((noreturn))) Example (https://godbolt.org/z/ePGd95sW=
z):


void FN_A(void);
void FN_B(void);
_Noreturn void NR_FN_A(void);
_Noreturn void NR_FN_B(void);

_Static_assert(_Generic((__typeof(*(FN_A))*){0}, __typeof(*(FN_B))*: 1), ""=
);
//OK =E2=9C=93
_Static_assert(_Generic((__typeof(*(NR_FN_A))*){0}, __typeof(*(NR_FN_B))*: =
1),
""); //ERROR =E2=9C=97
_Static_assert(_Generic((__typeof(*(FN_A))*){0}, __typeof(*(NR_FN_B))*: 1),
""); //ERROR =E2=9C=97

As you can see from the Compiler Explorer link, clang accepts all three, wh=
ich
is as it should be as per the standard, where _Noreturn is a function speci=
fier
(https://port70.net/~nsz/c/c11/n1570.html#6.7.4), which means it shouldn't =
even
go into the type.

(Personally, I don't even mind it going into the type just as long as two
otherwise identical _Noreturn functio declarations are deemed as having the
same type).

Regards,
Petr Skocik=