Re: fixing --check saying outputs not valid

[Dave Love <fx@gnu.org>]

Ludovic Courtès <ludo@gnu.org> writes:

> Dave Love <fx@gnu.org> skribis:
>>> Then you can run “guix build hwloc --check -L --no-grafts”, which will
>>> build hwloc locally and raise an error if hwloc:{out,lib} are not
>>> bit-identical to what you had in store.
>>
>> [Should that be documented as the procedure to use?]
>
> I think this is documented, but if you think it’s not or not in the
> right place, please tell!

I don't remember where I found out about using --check when packaging.
The manual doesn't mention --no-grafts in connexion with --check as far
as I can see.  I'd add something like

  You probably want to use --check with the --no-grafts option when
  checking a package you are developing, so that it gets rebuilt.

>> The trouble is that I don't get a second build with --check:
>>
>>   $ ./pre-inst-env guix build hwloc --check -L --no-grafts
>                                               ^^^^
> “--no-grafts” is taken as an argument to ‘-L’, and thus you only rebuilt
> the grafting derivation:

Thanks.  I shouldn't just do what I'm told :-/.  However, I don't
understand why -L is needed, or what the path should be.