[Bug libstdc++/113068] New: <ranges>: ranges::to<std::string>() | ranges::to<std::string>() is not a range adaptor

[Bug libstdc++/113068] New: <ranges>: ranges::to<std::string>() | ranges::to<std::string>() is not a range adaptor

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113068

            Bug ID: 113068
           Summary: <ranges>: ranges::to<std::string>() |
                    ranges::to<std::string>() is not a range adaptor
           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: ---

libstdc++ rejects the following code, which it shouldn't be.

  #include <ranges>
  #include <string>

  int main() {
    auto adaptor = std::ranges::to<std::string>() |
std::ranges::to<std::string>();
    auto str = adaptor(" ");
  }

https://godbolt.org/z/7TrzcdTcz

[Bug libstdc++/113068] <ranges>: ranges::to<std::string>() | ranges::to<std::string>() is not a range adaptor

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113068

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
                 CC|                            |ppalka at gcc dot gnu.org
   Last reconfirmed|                            |2023-12-18
     Ever confirmed|0                           |1
         Depends on|                            |112802

--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
IIUC this will be fixed by making ranges::to's closure object SFINAE-friendly.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112802
[Bug 112802] <ranges>: _ToClosure::operator() has no constraints

[Bug libstdc++/113068] <ranges>: ranges::to<std::string>() | ranges::to<std::string>() is not a range adaptor

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113068

--- Comment #2 from 康桓瑋 <hewillk at gmail dot com> ---
(In reply to Patrick Palka from comment #1)
> IIUC this will be fixed by making ranges::to's closure object
> SFINAE-friendly.

I didn't investigate the root cause in depth. So this should probably be
considered a duplicate of PR 112802, right?

[Bug libstdc++/113068] <ranges>: ranges::to<std::string>() | ranges::to<std::string>() is not a range adaptor

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113068

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
It could, but IMHO it's a different enough testcase/issue that a separate PR is
fine too.

[Bug libstdc++/113068] <ranges>: ranges::to<std::string>() | ranges::to<std::string>() is not a range adaptor

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113068

--- Comment #4 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++/113068] <ranges>: ranges::to<std::string>() | ranges::to<std::string>() is not a range adaptor

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113068
Bug 113068 depends on bug 112802, which changed state.

Bug 112802 Summary: <ranges>: _ToClosure::operator() has no constraints
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112802

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

[Bug libstdc++/113068] <ranges>: ranges::to<std::string>() | ranges::to<std::string>() is not a range adaptor

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113068

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |14.0

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed, thanks!