Policy for Dependencies

[Alex Merry]

On 2015-10-13 16:54, Christoph Cullmann wrote:
> Hi,
> 
>>> I'm not sure whether it's the best solution. The problem you try to 
>>> fix with
>>> it is distros breaking packaging. I agree with Martin K that this is 
>>> a huge
>>> problem and that it will happen - since the automation of packages I 
>>> also
>>> experienced that nobody looks at the output of optional dependencies 
>>> and the
>>> packaging breaks.
>>> 
>>> Given that I don't think we want an ENABLE_MINIMAL_DEPENDENCIES 
>>> switch, but
>>> rather a mode which will break if not found during distro builds.
>>> 
>>> Something like a "STRONGLY_RECOMMENDED" which is turned into 
>>> "REQUIRED" if
>>> distros build (and maybe also kdesrc-build), but is optional if 
>>> anybody else
>>> builds.
>>> 
>>> But I'm not sure how this could be done. Anyway, long story short: I 
>>> think we
>>> need the other way around. It should be optional by default, but 
>>> should be
>>> turned into stricter requirements on the linux distro case.
>> I would be happy with such an solution, too.
>> But I am not that optimistic that this is easy to achieve, how to 
>> ensure all
>> distros
>> turn this magic on?
>> 
>> The opposite direction at least would avoid the distro breakage and 
>> still allow
>> optional compiles for the "3rd party wants less dependencies" or 
>> "other platform
>> wants
>> less dependencies" use case.
>> 
>> Even if not optimal, some ENABLE_MINIMAL_DEPENDENCIES would in my eyes 
>> still
>> better than
>> the current situation, were either we have optional stuff that will 
>> make us
>> unhappy because
>> of broken distro packages or the devs unhappy that need to patch 
>> dependencies
>> out on their own.
>> 
>> e.g. Kåre did in most cases exactly that for the Windows build
>> (git at git.kde.org:scratch/sars/kate-windows),
>> which IMHO is sad.
> 
> My ECM proposal would be the following:
> 
> 1) add to KDECMakeSettings.cmake:
> 
> ################ Dependencies mode ####################################
> 
> if(KDE_SKIP_FULL_DEPENDENCIES)
>     unset(KDE_FIND_REQUIRED_OR_OPTIONAL)
>     set(KDE_TYPE_REQUIRED_OR_OPTIONAL "OPTIONAL")
> else()
>     set(KDE_FIND_REQUIRED_OR_OPTIONAL "REQUIRED")
>     set(KDE_FTYPE_REQUIRED_OR_OPTIONAL "REQUIRED")
> endif()
> 
> 2) use that e.g. in knotifications:
> 
> find_package(Phonon4Qt5 4.6.60 ${KDE_FIND_REQUIRED_OR_OPTIONAL} 
> NO_MODULE)
> set_package_properties(Phonon4Qt5 PROPERTIES
>    DESCRIPTION "Qt-based audio library"
>    TYPE ${KDE_TYPE_REQUIRED_OR_OPTIONAL}
>    PURPOSE "Required to build audio notification support")
> 
> That would at least make people happy that want no missing features and 
> allow
> me and others to work on minimizing the dependencies without annoying 
> others.
> 
> If there is some magic way to set KDE_SKIP_FULL_DEPENDENCIES for
> non-distro builds,
> that could be added later inside KDECMakeSettings.

I'm not a fan of the variable names - in particular, I think your 
original idea for an option name was better than 
"KDE_SKIP_FULL_DEPENDENCIES" - the existing KDE_SKIP_* variables are 
meant as things project authors define if they only want part of the 
module functionality, rather than as something for users/packagers to 
set. KDE_FIND_REQUIRED_OR_OPTIONAL also tells me essentially nothing 
about *why* it might be REQUIRED or optional when I'm reading the 
source.

That said, I'm on board with the overall idea.

Alex