https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63400
--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> --- GetSystemTimePreciseAsFileTime gives UTC, so would need adjustment for leap seconds to turn it into a sys_time. That's doable though. Alternatively, we could use it to implement a high performance chrono::utc_clock, and then define system_clock::now() in terms of that. The standard specifies utc_clock::now() as: "Returns: from_sys(system_clock::now()), or a more accurate value of utc_time." Also, if Windows FILETIME is measured in UTC then chrono::file_clock should use that too. So we might want to use a custom implementation of chrono::file_clock for Windows.
