Re: State of LilyPond with Guile 2.2

[David Kastrup]

Jonas Hahnfeld via Discussions on LilyPond development
<lilypond-devel@gnu.org> writes:

> Am Montag, dem 19.04.2021 um 11:48 +0200 schrieb David Kastrup:
>> Jonas Hahnfeld via Discussions on LilyPond development
>> <lilypond-devel@gnu.org> writes:
>> 
>> > Am Montag, dem 19.04.2021 um 10:39 +0200 schrieb Thomas Morley:
>> > 
>> > > Maybe a minimal example demonstrates it better than any explanation:
>> > > In lilypond master:
>> > > $ /home/hermann/lilypond-git/build-guile-2-2-6/out/bin/lilypond
>> > > scheme-sandbox
>> > > $ git checkout release/2.22.0-1
>> > > $ /home/hermann/lilypond-git/build/out/bin/lilypond scheme-sandbox
>> > > (Some error occurs, ignore)
>> > > $ git checkout master
>> > > $ /home/hermann/lilypond-git/build-guile-2-2-6/out/bin/lilypond
>> > > scheme-sandbox
>> > > ->
>> > > GNU LilyPond 2.23.3
>> > > ;;; note: source file
>> > > /home/hermann/lilypond-git/build-guile-2-2-6/out/share/lilypond/current/scm/lily/lily.scm
>> > > ;;;       newer than compiled
>> > > /home/hermann/lilypond-git/build-guile-2-2-6/out/share/lilypond/current/guile/ccache/2.2-LE-8-3.A/home/hermann/lilypond-git/scm/lily.scm.go
>> > > ...
>> > > ...
>> > > 
>> > > Obviously, it's not seen that unchanged master is indeed unchanged.
>> > 
>> > To know that, it would need to compute a hash or something of the file,
>> > but AFAICT Guile only looks at file modification dates (like most other
>> > software, including 'make'). And those did change when you switched
>> > between branches.
>> 
>> They should only change when the file contents change since Git
>> considers a file only changed (and touches it) when its file contents
>> hash changes.
>
> Yes, but switching between master and release/2.22.0-1 certainly forced
> git to write changed contents in between, even if the files are the
> same between the two runs on master.

Oh, sure.  I thought we were talking about files that were the same
between those two versions.

Yes, Git does not preserve file modification dates when it rewrites a
file, and it would be a Make nightmare if it did.

-- 
David Kastrup