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From: David Thompson <dave.thompson2@verizon.net>
Newsgroups: comp.lang.ada
Subject: Re: GNAT corrupted builds with below second changes
Date: Sun, 22 Apr 2018 01:53:46 -0400
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Date: 2018-04-22T01:53:46-04:00
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On Wed, 14 Mar 2018 17:56:13 -0500, "Randy Brukardt"
<randy@rrsoftware.com> wrote:

> "Alejandro R. Mosteo" <alejandro@mosteo.com> wrote in message 
> news:p8atvh$74r$1@dont-email.me...
<snip: gprbuild confused if modtimes within 1 second>

> ... we used to have such problems with Janus/Ada programs. I 
> believe it caused certain ACATS tests to intermittently fail. I think I 
> "fixed" that by introducing a delay into the compiler in certain 
> circumstances (the delay being barely noticable to humans, but long enough 
> to ensure that the time stamps are unique). ...
> It wouldn't surprise me if GNAT ran into similar issues -- the file 
> timestamps on Windows (which is what we were/are using) have a 2 second 
> granularity.

_FAT_, which was the file system used on MSDOS and (thus) early
Windows, has 2 second granularity. Windows NT introduced NTFS, with
granularity 100ns (and epoch in 1600!), but you can still have FAT for
data disks -- and for removable or detachable devices may prefer to,
as NTFS permissions get screwed up if you move a disk between machines
which are not both in the same 'domain' (in the MS sense, not DNS).

It is possible to get FAT (and NTFS) filesystem drivers on at least
some Unices, if you want to, and cause the problem there.