[Bug c++/51314] New: sizeof... and parentheses

[Bug c++/51314] New: sizeof... and parentheses

[marc.glisse at normalesup dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51314

             Bug #: 51314
           Summary: sizeof... and parentheses
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: marc.glisse@normalesup.org


Hello,

in some cases, g++ accepts sizeof...U (without parentheses) and in some other
cases it doesn't. I was going to report the case where it doesn't as a bug, but
after a look at the standard, it looks like it should always require the
parentheses. Well, I am not so sure, so here is one example of each:

template<int>struct A{};
template<class...U>void f(U...){
    A<sizeof...U> x; // template argument 1 is invalid
}


template<int...> struct Indices;
template<class> struct Next_increasing_indices;
template<int...I> struct Next_increasing_indices<Indices<I...> > {
    typedef Indices<I...,sizeof...I> type; // OK
};

[Bug c++/51314] sizeof... and parentheses

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51314

Daniel Krügler <daniel.kruegler at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |daniel.kruegler at
                   |                            |googlemail dot com

--- Comment #1 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2011-11-26 16:02:58 UTC ---
(In reply to comment #0)
> I was going to report the case where it doesn't as a bug, but after a look at
> the standard, it looks like it should always require the parentheses.

I agree, the grammar supports only 

sizeof...(/identifier/)

so both examples should be rejected.

[Bug c++/51314] [C++0x] sizeof... and parentheses

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51314

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-12-01
            Summary|sizeof... and parentheses   |[C++0x] sizeof... and
                   |                            |parentheses
     Ever Confirmed|0                           |1

[Bug c++/51314] [C++0x] sizeof... and parentheses

[marc.glisse at normalesup dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51314

--- Comment #2 from Marc Glisse <marc.glisse at normalesup dot org> 2012-04-19 21:19:23 UTC ---
Created attachment 27200
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27200
patch

s.cc: In function 'void f(U ...)':
s.cc:3:18: error: 'sizeof...' argument must be surrounded by parentheses
       A<sizeof...U> x; // template argument 1 is invalid
                  ^
s.cc:3:19: error: template argument 1 is invalid
       A<sizeof...U> x; // template argument 1 is invalid
                   ^
s.cc:3:22: error: invalid type in declaration before ';' token
       A<sizeof...U> x; // template argument 1 is invalid
                      ^
s.cc: At global scope:
s.cc:10:37: error: 'sizeof...' argument must be surrounded by parentheses
       typedef Indices<I...,sizeof...I> type; // OK
                                     ^

Error recovery is not that great in the first case, but fine in the second.

[Bug c++/51314] [C++0x] sizeof... and parentheses

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51314

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> 2012-04-30 16:36:51 UTC ---
Author: jason
Date: Mon Apr 30 16:36:37 2012
New Revision: 186988

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186988
Log:
    PR c++/51314
    * parser.c (cp_parser_sizeof_operand): Require parentheses for
    sizeof...

Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/parser.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/cpp0x/variadic76.C

[Bug c++/51314] [C++0x] sizeof... and parentheses

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51314

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jason at gcc dot gnu.org
         Resolution|                            |FIXED
   Target Milestone|---                         |4.8.0

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> 2012-04-30 17:02:46 UTC ---
Applied, thanks.