[build2] "Backwards modification times" in 0.9.0

[Boris Kolpackov]

Per Edin <info at peredin.com> writes:

> I'm trying to install build2 0.9.0 from stage.build2.org/0/
> (build2-toolchain-0.9.0-a.0.20181116172606.63932750d8ec) on macOS, but
> I'm receiving errors about backwards modification times.
> 
> [...] libbutl.a.d 2018-11-16 23:31:39.498914000 (0)
> [...] libbutl.a   2018-11-16 23:31:39
> 
> Any ideas why this is happening?

Yes, we are tracking down a bizarre modification time issue and
have instrumented staged build2 to detect this and print
additional diagnostics, which is what you are seeing.

Interestingly, so far we have only observed this on Windows and
FreeBSD (both as VMs) but not on Linux or Mac OS. Your report
is the first time we are seeing this on Mac but it looks like
the issue is somewhat different: it seems ar chops off the
fractional second part of the timestamp for some reason.

It's also strange that we are not observing the same issue.
Is there anything special about your setup?  Could you send
the output of the following commands:

$ sw_ver
$ diskutil info /  # Are you using APFS or HFS?
$ which ar ld
$ ld -v