[Bug libstdc++/71036] New: create_directory(p, ...) reports a failure when 'p' is an existing directory

[eric at efcs dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71036

            Bug ID: 71036
           Summary: create_directory(p, ...) reports a failure when 'p' is
                    an existing directory
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eric at efcs dot ca
  Target Milestone: ---

The create_directory functions should not report an error when the directory
they are trying to create already exists. The create_directory(...) functions
seem to report this error.

#include <experimental/filesystem>
#include <cassert>

using namespace std::experimental::filesystem;

int main() {
  path p = "/tmp/foo";
  assert(!exists(p));
  create_directory(p); // create the directory once
  create_directory(p); // THROWS!
}