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 E96FB3858C2F; Fri,  6 Oct 2023 05:31:11 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E96FB3858C2F
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1696570271;
	bh=EnUSi9XQ7SNf/4t52Iwccz8acOzCp9l703mYKcP+Ihg=;
	h=From:To:Subject:Date:From;
	b=ZjmRTLA7otA2Ckyp0Xhj54rtzCRUOTKjXWtljAc5D+XBa8fuuTGdZS9A49BDfsCCH
	 0Quw6idDim011HQdLaWr5NVlT/1FJS+cHiy5d1NXihKjAusxkaX3oMrLx6hQKnoe9P
	 sdKEI98+bsflz/MI/ReJSTe6VsjEP3sboxy/P3Hg=
From: "hewillk at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/111712] New: Syntax error when passing function parameter
 as NTTP in requires-clause
Date: Fri, 06 Oct 2023 05:31:11 +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: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: hewillk 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-111712-4@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=3D111712

            Bug ID: 111712
           Summary: Syntax error when passing function parameter as NTTP
                    in requires-clause
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

Regardless of whether the code is well-formed or not, this should be valid
syntax

https://godbolt.org/z/4qM9nG4WP

#include <type_traits>

template<bool B>
void f(std::bool_constant<B> b)
  requires requires { typename std::bool_constant<b()>; };

int main() {
  f(std::true_type{});
}

However, GCC givs

<source>:5:54: error: template argument 1 is invalid
<source>:5:37: error: invalid use of template-name 'std::bool_constant' wit=
hout
an argument list
    5 |   requires requires { typename std::bool_constant<b()>; };
      |                                     ^~~~~~~~~~~~~
In file included from <source>:1:
/opt/compiler-explorer/gcc-trunk-20231005/include/c++/14.0.0/type_traits:12=
0:11:
note: 'template<bool __v> using std::bool_constant =3D std::__bool_constant=
<__v>'
declared here
  120 |     using bool_constant =3D __bool_constant<__v>;
      |           ^~~~~~~~~~~~~
<source>:5:50: error: expected '(' before '<' token
    5 |   requires requires { typename std::bool_constant<b()>; };
      |                                                  ^
      |                                                  (
<source>:5:55: error: expected primary-expression before ';' token
    5 |   requires requires { typename std::bool_constant<b()>; };
      |                                                       ^=