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 32093385DC00; Sat,  4 Apr 2020 15:45:43 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 32093385DC00
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1586015143;
 bh=oCtXHWf8QsZFOozBL36RWA40yOfPaSn6TPAc77hr7eM=;
 h=From:To:Subject:Date:In-Reply-To:References:From;
 b=yv8kj5ZRbxAzVdLvIG+MdqJcpbMIr1CncmS5wl3ROx/Ab0kcmmJgtbfk7SWKzzReU
 yneqEzhovJ7hvpXGo5k4OmgCce7K0IFch++kTxt1bh8/2JyQ/6P515pCzjcCeQtsoz
 NbGfM4X3wNpKV/JslTRdv6Wqlht18cPeVbzXsMrU=
From: "dimitri.gorokhovik at free dot fr" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/94485] [10.0.1, c++2a] g++ optimizes away necessary code,
 accepts arbitrary inline asm
Date: Sat, 04 Apr 2020 15:45:43 +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: dimitri.gorokhovik at free dot fr
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: 
Message-ID: <bug-94485-4-5LJJ3G9EKs@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-94485-4@http.gcc.gnu.org/bugzilla/>
References: <bug-94485-4@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
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <http://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Sat, 04 Apr 2020 15:45:43 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94485

--- Comment #3 from Dimitri Gorokhovik <dimitri.gorokhovik at free dot fr> =
---
(In reply to Andrew Pinski from comment #2)
> Also c++20 changes constexpr is handled which is why inline asm is accept=
ed
> now IIRC.

This code:

constexpr auto f()
{
  asm("before:");
  constexpr auto r =3D 129;
  asm("after:");

  return r;
};

produces:
bug-2.cpp: In function =E2=80=98constexpr auto f()=E2=80=99:
bug-2.cpp:3:3: error: inline assembly is not a constant expression
    3 |   asm("before:");
      |   ^~~
bug-2.cpp:3:3: note: only unevaluated inline assembly is allowed in a
=E2=80=98constexpr=E2=80=99 function in C++2a=