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 4493B3858401; Fri, 18 Aug 2023 13:34:19 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4493B3858401
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1692365659;
	bh=fpR7ACBG0PUUsutYZZ+/betp4Rp9RhYbueHK52w61BI=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=MJnbPLpIcKJgQFGUKrDsc6lItMFczCKjka6Uu8uGsHTFzntV+D6bIJLPppMSvqrHh
	 WIZmNglIEip3LMmKnyHjFhD/X6lBXFX5qdHx6OoMnUaI7bDPA1nO2t2DcKsZqixjqO
	 j7/l7+ZxM1EXYOUVm57Id5TyZxHhv3wymqikh/pc=
From: "xry111 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/111058] __builtin_nans (and its friends for other
 floating-point types) compiles to an external call to __builtin_nans for
 unsupported tag
Date: Fri, 18 Aug 2023 13:34:19 +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: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: xry111 at gcc dot gnu.org
X-Bugzilla-Status: NEW
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: 
Message-ID: <bug-111058-4-CUX7bPoo6O@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-111058-4@http.gcc.gnu.org/bugzilla/>
References: <bug-111058-4@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=3D111058

--- Comment #6 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to joseph@codesourcery.com from comment #5)
> We should absolutely *not* generate calls to a non-existent function=20
> "nans" based on a long-obsolescent standard proposal.  The modern way to=
=20
> generate a signaling NaN with given payload, as specified in C23, is to=20
> generate a signaling NaN with one of the *_SNAN macros (FLT128_SNAN in=20
> this case) in <float.h>, then use the relevant setpayload function=20
> (setpayloadf128 in this case) to set its payload.
>=20
> I don't think there is any bug here at all.

But generating an external call to __builtin_* just does not make sense at =
all.

If the payload won't be supported, we should just emit a diagnostic and rej=
ect
the code.=