[Bug libstdc++/118842] New: `std::result_of` and `std::result_of_t` should be removed in C++20

[cmingyi01 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118842

            Bug ID: 118842
           Summary: `std::result_of` and `std::result_of_t` should be
                    removed in C++20
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: cmingyi01 at gmail dot com
  Target Milestone: ---

`std::result_of` and `std::result_of_t` should be removed in C++20 but they are
still enabled in libstdc++ in C++20.

See https://compiler-explorer.com/z/zWWPnavK4.