bug#64106: `modify-services` no longer affects multiple instances of the same service

[Ludovic Courtès]

Hi,

Josselin Poiret <dev@jpoiret.xyz> skribis:

> "David Wilson" <david@daviwil.com> writes:
>
>> Hi Guix!
>>
>> Recently there was a change to the behavior of `modify-services` that adds 
>> logic to check for any unused clauses so that an exception can be raised to 
>> alert the user of this case.
>>
>> https://git.savannah.gnu.org/cgit/guix.git/commit/?id=181951207339508789b28ba7cb914f983319920f
>>
>> It seems that the new logic has a bug that prevents a used clause from being 
>> executed on more than one instance of a compatible service in a single 
>> execution of `modify-services`.  Here's a new test case for 
>> `gnu/tests/services.scm` that exhibits the issue:
>
> This was intended, but was probably not a good idea.

It wasn’t really intended, more a side effect of the implementation, and
I agree it should be fixed.

Ludo’.