[Bug libstdc++/86603] New: `__cpp_lib_list_remove_return_type` misplaced in the <version> header

[ensadc at mailnesia dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86603

            Bug ID: 86603
           Summary: `__cpp_lib_list_remove_return_type` misplaced in the
                    <version> header
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ensadc at mailnesia dot com
                CC: redi at gcc dot gnu.org
  Target Milestone: ---

In <version>, __cpp_lib_list_remove_return_type is defined when __cplusplus ==
201703. This is inconsistent with <list> and <forward_list>, where the macro is
defined (and the corresponding feature is enabled) only in C++2a mode.