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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: GNAT corrupted builds with below second changes
Date: Sun, 22 Apr 2018 08:31:04 +0100
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Date: 2018-04-22T08:31:04+01:00
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"Alejandro R. Mosteo" <alejandro@mosteo.com> writes:

> I've observed that gprbuild seems to not detect that a file is changed
> if less than a second has elapsed. I will guess here that the
> timestamp being used has second precision.

Looking at a .ali file, the dependencies are recorded in lines like

D ada.ads               20170106103348 76789da1 ada%s

where 20170106103348 is the date/time to 1 second precision, and
76789da1 is a checksum of the file's contents. I'd imagine that gprbuild
looks at the timestamp first; not sure about the checksum, but certainly
needed for -m processing (only recompile if semantically modified).