[Bug c++/89196] New: clock::to_time_t(ftime)

[bremende55 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89196

            Bug ID: 89196
           Summary: clock::to_time_t(ftime)
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bremende55 at gmail dot com
  Target Milestone: ---

Example in
https://en.cppreference.com/w/cpp/filesystem/last_write_time
compiles fine with g++ 8.1 and 8.2, but not with 9.0.1
Error message:

lastwritetime.cpp: In Funktion »int main()«:
lastwritetime.cpp:16:50: Fehler: »to_time_t« ist kein Element von
»std::chrono::time_point<std::filesystem::__file_clock>::clock« {aka
»std::filesystem::__file_clock«}
   16 |     std::time_t cftime = decltype(ftime)::clock::to_time_t(ftime);
      |                                                  ^~~~~~~~~
lastwritetime.cpp:22:38: Fehler: »to_time_t« ist kein Element von
»std::chrono::time_point<std::filesystem::__file_clock>::clock« {aka
»std::filesystem::__file_clock«}
   22 |     cftime = decltype(ftime)::clock::to_time_t(ftime);

g++ --version
g++ (GCC) 9.0.1 20190203 (experimental)

g++ -v
Es werden eingebaute Spezifikationen verwendet.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-pc-linux-gnu/9.0.1/lto-wrapper
Ziel: x86_64-pc-linux-gnu
Konfiguriert mit: ../gcc-9-20190203/configure --enable-languages=c,c++
--disable-multilib
Thread-Modell: posix
gcc-Version 9.0.1 20190203 (experimental) (GCC)