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 F0C26385357C; Wed, 24 Aug 2022 13:26:43 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org F0C26385357C
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1661347603;
	bh=JpGeY5W4kaEBSDvSSf41PFSijHTbpOH3o5iWkqcQZrU=;
	h=From:To:Subject:Date:From;
	b=g82K0yS2kKksx/4UT30/pEEiVPT3bLSO4r9huATWFFXCQk6yt6MxyAKllvCt/K/xK
	 aH28n1OlpMf4Ee7jDR+Omt1SdpwsBia/drGh11xzM6cZO3nCMeio1CrQCo0kDdKgCS
	 zdLkQtAnR8CaV6/NonxQEvMLCpFC2gfw1CkR89lI=
From: "jakob at schmutz dot co.uk" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/106734] New: [requires] std::same_as in compound
 requirements doesn't produce expected result
Date: Wed, 24 Aug 2022 13:26:43 +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: 12.2.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakob at schmutz dot co.uk
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-106734-4@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=3D106734

            Bug ID: 106734
           Summary: [requires] std::same_as in compound requirements
                    doesn't produce expected result
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakob at schmutz dot co.uk
  Target Milestone: ---

On gcc version 12.2.0 (and 11.3.0) I would expect the following code


```
#include <iostream>

struct Bar {
};

int main()
{
    Bar bar;
    constexpr bool same =3D requires
    {
        { bar } -> std::same_as<Bar>;
    };

    constexpr bool conv =3D requires
    {
        { bar } -> std::convertible_to<Bar>;
    };

    if constexpr (std::same_as<decltype(bar), Bar>)
    {
        std::cout << "AS SAME" << std::endl;
    }

    if constexpr (std::is_same_v<decltype(bar), Bar>)
    {
        std::cout << "IS SAME" << std::endl;
    }

    if constexpr (same)
    {
        std::cout << "REQUIRES SAME" << std::endl;
    }

    if constexpr (conv)
    {
        std::cout << "CONVERTIBLE" << std::endl;
    }

    return 0;
}
```

to return

```
AS SAME
IS SAME
REQUIRES SAME
CONVERTIBLE
```

based on how how [compound
requires](https://en.cppreference.com/w/cpp/language/requires) section reads


but instead it returns

```
IS SAME
REQUIRES SAME
CONVERTIBLE
```

compiled with `g++ temp.cpp -std=3Dc++20`

compiling with `clang++ temp.cpp -std=3Dc++20` produces the expected output=