https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797
--- Comment #11 from Jack Howarth <howarth.at.gcc at gmail dot com> --- (In reply to Francois-Xavier Coudert from comment #10) > (In reply to Jack Howarth from comment #9) > > > The only thing I can think of is that maybe, just maybe, it's due to > filesystem timestamp granularity? My 10.13 system is running on APFS > filesystem, which has 1 ns granularity (smaller than 1 s for HFS+). That sounds much more likely as the trigger for the problem. I only have hard drives to test 10.13 on so I am stuck with HFS (and wouldn't press the envelope with APFS without using it on an SSD).