[Bug libstdc++/112802] New: <ranges>: _ToClosure::operator() has no constraints

[Bug libstdc++/112802] New: <ranges>: _ToClosure::operator() has no constraints

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112802

            Bug ID: 112802
           Summary: <ranges>: _ToClosure::operator() has no constraints
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

which means this is not SFINAE-friendly. That's not standard compliance, right?

  #include <ranges>
  #include <vector>

  template<class T>
  concept test = requires { std::ranges::to<std::vector<int>>()(T{}); };

  static_assert(!test<int>); // hard error in libstdc++

https://godbolt.org/z/Tasba18Kv

[Bug libstdc++/112802] <ranges>: _ToClosure::operator() has no constraints

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112802

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Patrick has a pending patch to improve those adaptors.

[Bug libstdc++/112802] <ranges>: _ToClosure::operator() has no constraints

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112802

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ppalka at gcc dot gnu.org
   Target Milestone|---                         |14.0
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-12-06
             Status|UNCONFIRMED                 |ASSIGNED

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
I can fix this as a follow-up.

[Bug libstdc++/112802] <ranges>: _ToClosure::operator() has no constraints

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112802

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:4f54e656788be3268dd45eb036447464a937fae9

commit r14-6668-g4f54e656788be3268dd45eb036447464a937fae9
Author: Patrick Palka <ppalka@redhat.com>
Date:   Mon Dec 18 18:05:36 2023 -0500

    libstdc++: Make ranges::to closure objects SFINAE-friendly [PR112802]

    This also happens to fix composition of these closure objects.

            PR libstdc++/112802
            PR libstdc++/113068

    libstdc++-v3/ChangeLog:

            * include/std/ranges (__detail::_To::operator()): Add constraints.
            (__detail::_To2::operator()): Likewise.
            * testsuite/std/ranges/conv/1.cc (test_sfinae): New test.
            (test_composition): New test.

[Bug libstdc++/112802] <ranges>: _ToClosure::operator() has no constraints

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112802

Patrick Palka <ppalka at gcc dot gnu.org> changed:

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

--- Comment #4 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed