[Bug c++/61857] New: An init-capturing lambda is parsed incorrectly when used in a braced-init-list

[Bug c++/61857] New: An init-capturing lambda is parsed incorrectly when used in a braced-init-list

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61857

            Bug ID: 61857
           Summary: An init-capturing lambda is parsed incorrectly when
                    used in a braced-init-list
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ville.voutilainen at gmail dot com

struct A { 
    A(int val){} 
};

int main()
{ 
    A a{ [x=123]{ return x; }() }; 
} 

init-capture2.cpp: In function ‘int main()’:
init-capture2.cpp:7:11: error: ‘x’ was not declared in this scope
     A a{ [x=123]{ return x; }() }; 

Clang recently fixed this bug, for clang it was caused by the parser
getting confused with the lambda and designated initializers, perhaps
gcc has a similar bug. With parentheses the code works:

struct A { 
    A(int val){} 
};

int main()
{ 
    A a( [x=123]{ return x; }() ); 
}
>From gcc-bugs-return-456803-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sun Jul 20 12:28:47 2014
Return-Path: <gcc-bugs-return-456803-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 5995 invoked by alias); 20 Jul 2014 12:28:45 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 5914 invoked by uid 48); 20 Jul 2014 12:28:41 -0000
From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/61857] An init-capturing lambda is parsed incorrectly when used in a braced-init-list
Date: Sun, 20 Jul 2014 12:28:00 -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: 4.10.0
X-Bugzilla-Keywords: rejects-valid
X-Bugzilla-Severity: normal
X-Bugzilla-Who: redi at gcc dot gnu.org
X-Bugzilla-Status: NEW
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_status cf_reconfirmed_on everconfirmed
Message-ID: <bug-61857-4-Y9WDBHklWV@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-61857-4@http.gcc.gnu.org/bugzilla/>
References: <bug-61857-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2014-07/txt/msg01394.txt.bz2
Content-length: 401

https://gcc.gnu.org/bugzilla/show_bug.cgi?ida857

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-07-20
     Ever confirmed|0                           |1

[Bug c++/61857] An init-capturing lambda is parsed incorrectly when used in a braced-init-list

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61857

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
In our case the issue is slightly different, the problem is in
cp_parser_initializer_list, here:

      cp_parser_parse_tentatively (parser);
      cp_lexer_consume_token (parser->lexer);
      designator = cp_parser_constant_expression (parser, true, &non_const);
      cp_parser_require (parser, CPP_CLOSE_SQUARE, RT_CLOSE_SQUARE);
      cp_parser_require (parser, CPP_EQ, RT_EQ);
      if (!cp_parser_parse_definitely (parser))
        designator = NULL_TREE;
      else if (non_const)
        require_potential_rvalue_constant_expression (designator);

where cp_parser_constant_expression is tentatively called. I think it can be
solved by looking forward for the '=', similarly to other GNU extensions, for
example compound literals.

[Bug c++/61857] An init-capturing lambda is parsed incorrectly when used in a braced-init-list

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61857

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |paolo.carlini at oracle dot com

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Mine.

[Bug c++/61857] An init-capturing lambda is parsed incorrectly when used in a braced-init-list

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61857

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
           Assignee|paolo.carlini at oracle dot com    |unassigned at gcc dot gnu.org
   Target Milestone|---                         |5.0

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed.