[Bug c++/58435] New: Applying a type transformation to a list: const ignored

[Bug c++/58435] New: Applying a type transformation to a list: const ignored

[iavr at image dot ntua.gr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58435

            Bug ID: 58435
           Summary: Applying a type transformation to a list: const
                    ignored
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: iavr at image dot ntua.gr

The following applies a type transformation F to a list L of types T..., in
particular for a transformation that adds "const":

------------------------------------------------------------------------

   template <template <typename...> class F, typename P> struct apply;

   template <
       template <typename...> class F,
       template <typename...> class L, typename... T
   > struct apply <F, L <T...> > { typedef L <F <T>...> type; };

   template <typename T> using map = const T;
   template <typename> struct A { };
   template <typename> void dummy();

   int main() { dummy <apply <map, A <int> >::type>(); }

------------------------------------------------------------------------

It fails to link because of

   undefined reference to `void dummy<A<int> >()'

instead of the expected

  undefined reference to `void dummy<A<const int> >()'

i.e., "const" is ignored. It works for any other transformation I have tried.

[Bug c++/58435] Applying a type transformation to a list: const ignored

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58435

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-09-16
     Ever confirmed|0                           |1

[Bug c++/58435] Applying a type transformation to a list: const ignored

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58435

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

template<typename T, typename U>
struct same { static const bool value = false; };

template<typename T>
struct same<T, T> { static const bool value = true; };

template <template <typename> class F, typename T> struct apply
{ typedef F<T> type; };

template <typename T> using map = const T;

static_assert(same<apply<map, int>::type, const int>::value, "");

[Bug c++/58435] Applying a type transformation to a list: const ignored

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58435

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
   Target Milestone|---                         |4.9.0

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Mine.

[Bug c++/58435] Applying a type transformation to a list: const ignored

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58435

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

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed for 4.9.0.

[Bug c++/58435] Applying a type transformation to a list: const ignored

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58435

--- Comment #5 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> ---
Author: paolo
Date: Tue Sep 17 17:46:03 2013
New Revision: 202662

URL: http://gcc.gnu.org/viewcvs?rev=202662&root=gcc&view=rev
Log:
/cp
2013-09-17  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/58435
    * pt.c (tsubst, [BOUND_TEMPLATE_TEMPLATE_PARM]): Take into account
    the cp_type_quals (r) too.

/testsuite
2013-09-17  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/58435
    * g++.dg/cpp0x/alias-decl-38.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/alias-decl-38.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/pt.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/58435] Applying a type transformation to a list: const ignored

[iavr at image dot ntua.gr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58435

--- Comment #6 from iavr at image dot ntua.gr ---
(In reply to paolo@gcc.gnu.org from comment #5)
> Author: paolo
> Date: Tue Sep 17 17:46:03 2013
> New Revision: 202662
> 

Hi,

Thanks a lot for your immediate response. However, I have to report that
exactly the same problem occurs for "volatile" and "const volatile", as I just
found out. Maybe these have been fixed as well already?

Yannis

[Bug c++/58435] Applying a type transformation to a list: const ignored

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58435

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Of course. Just look at the testcase.