Subject: Re: bug#26734: Snippets (even empty ones) of tar sources reset the timestamps of all files

From: Clément Lassieur <[email-masked]>
Date: Tue, 02 May 2017 15:17:29 +0200

Ludovic Courtès <[email-masked]> writes:

> Clément Lassieur <[email-masked]> skribis:
>
>> I tried to patch 'patch-and-repack', but it triggers a full
>> rebuild...  WDYT?
>
> Right, it’s expected to trigger a full rebuild, so this should be fixed
> in ‘core-updates’.

Yes, but is there a way to test the patch on one package without having
first to rebuild everything?

> I guess we’ll have to collect the timestamps of all non-symlink files¹
> in step #1 and to reapply them with ‘set-file-time’ from (guix build
> utils) after step #2.

Does that mean that symlinks will still have their timestamps changed?
To me that is a half-solution...  Wouldn't it be easier to collect all
recently modified files (those modified by snippet and patches), and set
their timestamp to "1 January 1970", without changing the other files?
That means removing the --mtime option from tar at step 3.

> Thoughts?  Would you like to do that?

Sure :-)

> ¹ Because Guile provides bindings for ‘utime’, which does not support
>   setting timestamps on symlinks.

If the guile binding doesn't support setting timestamps on symlinks, I
guess we can still use another way, like a system touch.