[Bug c++/66988] New: [concepts] concept with template template parameter satisfied erroneously

[Bug c++/66988] New: [concepts] concept with template template parameter satisfied erroneously

[eric.niebler at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66988

            Bug ID: 66988
           Summary: [concepts] concept with template template parameter
                    satisfied erroneously
           Product: gcc
           Version: c++-concepts
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eric.niebler at gmail dot com
  Target Milestone: ---

Pretty sure the static assert in the program below should not fire, but it
does.

#include <type_traits>

template <template <class...> class T, class... U>
concept bool _Valid = requires { typename T<U...>; };

template <class T>
using __t = typename T::type;

template <class T>
struct __has_type : std::false_type { };

template <class T>
  requires _Valid<__t, T>
struct __has_type<T> : std::true_type { };

static_assert(!__has_type<int>(), "");

[Bug c++/66988] [concepts] concept with template template parameter satisfied erroneously

[andrew.n.sutton at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66988

--- Comment #1 from Andrew Sutton <andrew.n.sutton at gmail dot com> ---
I don't know if that's strictly a concepts issue. My guess is that the template
argument coersion of this argument:

   template <typename> class

to this parameter:

   template <typename...> class

is not succeeding.

[Bug c++/66988] [concepts] concept with template template parameter satisfied erroneously

[eric.niebler at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66988

--- Comment #2 from Eric Niebler <eric.niebler at gmail dot com> ---
I thought that, too. But this program has the same problem:

#include <type_traits>

template <template <class> class T, class U>
concept bool _Valid = requires { typename T<U>; };

template <class T>
using __t = typename T::type;

template <class T>
struct __has_type : std::false_type { };

template <class T>
  requires _Valid<__t, T>
struct __has_type<T> : std::true_type { };

static_assert(!__has_type<int>(), "");

[Bug c++/66988] [concepts] concept with template template parameter satisfied erroneously

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66988

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Sat Jul 25 03:19:54 2015
New Revision: 226203

URL: https://gcc.gnu.org/viewcvs?rev=226203&root=gcc&view=rev
Log:
        PR c++/66988
        * constraint.cc (satisfy_type_constraint): Use error_operand_p.

Added:
    branches/c++-concepts/gcc/testsuite/g++.dg/concepts/req16.C
Modified:
    branches/c++-concepts/ChangeLog.concepts
    branches/c++-concepts/gcc/cp/constraint.cc

[Bug c++/66988] [concepts] concept with template template parameter satisfied erroneously

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66988

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed.