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 43F40385841A; Wed, 27 Mar 2024 00:20:18 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 43F40385841A
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1711498818;
	bh=VxliiLtpS57cZ5ZCnxAWCX1GdSjng5E5z7nGsKV6uaQ=;
	h=From:To:Subject:Date:From;
	b=cN52LYvtU/x9OVEkAFVps+Jwn/6ejN4Jfb1VwJDecn5MjL5Uyhi8LNz3EQoIf4p1i
	 eVsYUT9k1zGEhf1lENLgbBp9LhVVcmof/i7C6sijZ8iJJLuqqmzjNh1I/7sES7lduV
	 1fnq97QRWBGDJmS+lyhJhqrYcCPMDaLrJV2NeslM=
From: "christoph.schied at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/114491] New: incorrect identifier namespacing with variadic
 templates
Date: Wed, 27 Mar 2024 00:20:17 +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: christoph.schied 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
 attachments.created
Message-ID: <bug-114491-4@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=3D114491

            Bug ID: 114491
           Summary: incorrect identifier namespacing with variadic
                    templates
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: christoph.schied at gmail dot com
  Target Milestone: ---

Created attachment 57818
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D57818&action=3Dedit
same source code as posted in the description

The following code fails to compile with g++, however it works with clang. I
tried various versions of gcc in godbolt (https://godbolt.org/z/xqfoc4Yce)
using std=3Dc++17 and std=3Dc++20 and the code fails to compile on all vers=
ions. It
appears that the dependent type T gets confused with the template argument =
of
the function.

template<typename A, typename... X>
void works()
{
    typename A::T var;
}

template<typename A, typename... T>
void broken()
{
    typename A::T var; /* A::T and T seem to clash */
}


results in:
<source>: In function 'void broken()':
<source>:10:19: error: parameter packs not expanded with '...':
   10 |     typename A::T var; /* A::T and T seem to clash */
      |                   ^~~
<source>:10:19: note:         'T'=