[Bug libstdc++/85632] New: std::filesystem::space or std::experimental::filesystem::space does not return correct information

[bandinfinite at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85632

            Bug ID: 85632
           Summary: std::filesystem::space or
                    std::experimental::filesystem::space does not return
                    correct information
           Product: gcc
           Version: 7.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bandinfinite at gmail dot com
  Target Milestone: ---

I'm typing this report on my phone so forgive me for not perfect formatting.
The bug is simple, filesystem::space() probably won't return correct info for
most modern  storage device that contain a big enough partition (anything more
than 4GB   counts). The cause of this bug is simply that the author forgot
static_cast<uintmax_t>(data retrieved by statvfs) before the calculation. So
the fix is also trivial and can definitely backport to all version  contain
experimental::filesystem.
The latest 8.1 release shares this bug, confirmed with the git mirror hours
ago.