[Bug c++/55931] New: Constexpr member function inside a static member is not working

[Bug c++/55931] New: Constexpr member function inside a static member is not working

[vince.rev at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

             Bug #: 55931
           Summary: Constexpr member function inside a static member is
                    not working
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: vince.rev@gmail.com


The call of a constexpr member of a class into a static member of the same
class is not working. This is illustrated by the following code:
(tested on g++ 4.7.1 and 4.7.2, but it may also affect g++ 4.8)

-------------------------------------------------------------------
#include <iostream>
#include <type_traits>

template<typename Type>
class Test
{
    public:
        constexpr Test(const Type val) : _value(val) {}
        constexpr Type get() const {return _value;}
        static void test()
        {
            static constexpr Test<int> x(42);
            std::integral_constant<int, x.get()> i; // This is not working
            std::cout<<i<<std::endl;
        }
    protected:
        Type _value;
};

int main(int argc, char *argv[])
{
    static constexpr Test<int> x(42);
    std::integral_constant<int, x.get()> i; // This is working
    std::cout<<i<<std::endl;
    Test<double>::test();
    return 0;
}
-------------------------------------------------------------------

which produces the following error:

-------------------------------------------------------------------
main.cpp: In static member function ‘static void Test<Type>::test()’:
main.cpp:13:48: erreur: invalid use of ‘Test<Type>::get<int>’ to form a
pointer-to-member-function
main.cpp:13:48: note:   a qualified-id is required
main.cpp:13:48: erreur: could not convert template argument
‘x.Test<Type>::get<int>()’ to ‘int’
main.cpp:13:51: erreur: invalid type in declaration before ‘;’ token
-------------------------------------------------------------------

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2013-01-10 05:18:11 UTC ---
>             std::integral_constant<int, x.get()> i; // This is not working

Most likely because Test<int> is not complete at the time of parsing.

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

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

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

--- Comment #2 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2013-01-11 13:22:13 UTC ---
When using gcc 4.8.0 20130106 (experimental)

with flags

-Wall -std=c++11 -pedantic

I get an internal compiler error for the line:

static constexpr Test<int> x(42);

"12|internal compiler error: tree check: expected target_expr, have cast_expr
in check_initializer, at cp/decl.c:5699"

Should this be reported separately?

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

--- Comment #3 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2013-01-11 13:26:46 UTC ---
(In reply to comment #1)
> Most likely because Test<int> is not complete at the time of parsing.

But this should be considered as a compiler defect, right?

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-01-11
     Ever Confirmed|0                           |1
           Severity|major                       |normal

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-01-11 14:37:36 UTC ---
(In reply to comment #2)
> Should this be reported separately?

Yes please, but note this PR in the comments and vice versa, in case they turn
out to be fixed by the same change.

(In reply to comment #3)
> But this should be considered as a compiler defect, right?

Right.

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

--- Comment #5 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2013-01-11 18:32:13 UTC ---
The ICE bug of 4.8.0 has been submitted as bug 55944

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |jason at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> 2013-02-15 19:29:29 UTC ---
Created attachment 29473
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29473
55931.patch

Patch waiting for 4.8 to branch.

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

--- Comment #7 from Jason Merrill <jason at gcc dot gnu.org> 2013-03-17 02:40:06 UTC ---
Author: jason
Date: Sun Mar 17 02:39:51 2013
New Revision: 196746

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196746
Log:
    PR c++/55931
    * parser.c (cp_parser_template_argument): Don't
    fold_non_dependent_expr.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-template4.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/parser.c

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.9.0

--- Comment #8 from Jason Merrill <jason at gcc dot gnu.org> 2013-04-01 21:05:51 UTC ---
Fixed for 4.9.

[Bug c++/55931] [C++11] Constexpr member function inside a static member is not working

[rmansfield at qnx dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55931

Ryan Mansfield <rmansfield at qnx dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rmansfield at qnx dot com

--- Comment #9 from Ryan Mansfield <rmansfield at qnx dot com> ---
(In reply to Jason Merrill from comment #6)
> Created attachment 29473 [details]
> 55931.patch
> 
> Patch waiting for 4.8 to branch.

Jason, do you mind moving this over to the 4.8 branch? It seems you intended
to.