[GCompris-devel] HEADS UP: git submodule on master

[Ben Cooksley]

On Fri, Oct 23, 2015 at 7:39 AM, Holger Kaelberer <hk at elberer.de> wrote:
> Hi

Hi Holger,

>
> On 21.10.2015 01:16, Holger Kaelberer wrote:
>
>> Merged with master.
>>
>> Note for all devs:
>>
>> There is a git submodule on master now. Therefore after git pull-ing do an
>> initial
>>
>> git submodule init && git submodule update
>>
>> before building.
>
>
> This submodule broke the CI builds of gcompris and I got some feedback on it
> from Ben [1].
>
> To sum up: For packaging to always and only rely on an external dependency
> like we do atm is not what packagers and ci-admins prefer.
>
> qml-box2d was made a submodule and is built automatically to make handling
> convenient for developers. I expected that we need to adjust the current
> build once GCompris-qt is upstream in some distribution's package repo. If
> we have to change building again now for ci, let's agree upon how we do it
> first.
>
> That's the status quo:
>
> - Right now the qml-box2d dependency is contained as git submodule and
> automatically built in the build-dir and installed into
> INSTALL_PREFIX/lib/qml. Without the submodule being checked out the build
> fails.
>
> - On desktop: Most distros (checked ubuntu, FC) don't package qml-box2d (in
> the version we need it). So right now we need to  provide the plugin in an
> installation/runtime. Devs need to compile(+install) it for building and
> testing.
>
> - On android (and the other experimental targets) there is of course no
> other way than to package the plugin in an apk. At build time it needs to be
> present somewhere, if it is installed below the system's QML2_IMPORT_PATH it
> gets pulled into the apk during build.
>
> - Same probably for CI (builds afaik only linux/gcc atm): the module needs
> to be present somewhere in the env.
>
> According to Ben the preferred way for packaging as well as for ci is to set
> up the build-env properly (injecting the dependency) prior to building
> gcompris itself.
>
> The same would probably be the case for a packaging scenario where qml-box2d
> would be provided as a package. (Correct me if I'm wrong)
>
> Options we have:
>
> 1. Remove the submodule/automatic build completely and leave it to the
> developer/ci/packager set up his build-env properly. That's what I wanted to
> avoid when I added the submodule. In this case the dev would need to clone
> qml-box2d + qmake && make && make install it for each target platform/Qt
> target he wants to build for. Once installed the module is in place.
> Not sure if this is possible for packaging as the installed dependencies
> must be pulled into the package then.
>
> 2. Make the build optional with somehting like -DBUILD_QML_BOX2D. The
> default would be to let it fetch from the system/env and error out if it is
> not found. In this case a developer would still have the option to let it
> build automatically if passing -DBUILD_QML_BOX2D
>
> 2.a) As 2 but with inverted default: Build per default the dependency and
> let it switch off with something like -DUSE_SYSTEM_QML_BOX2D. In this case
> the ci/packager would need to pass the build-switch.
>
> 3. As 2 but remove the submodule and turn the dependency into a cmake
> ExternalProject directly pulling in from a remote git-URL. At build-time the
> dependency would then get cloned into the build-prefix and build
> automatically. This gets rid of the submodule stuff with the overhead of
> needing to clone once for each build-location and target.
>
> 3.a) As 2.a but with ExternalProject instead of the submodule.
>
> 4. Build and link qml-box2d statically to gcompris, should be possible if
> the module is registered manually at app startup. This would solve all
> problems at runtime, but smells like hacking around missing dynamic
> dependencies.
>
> Personally I'd vote for 2 which leaves all options while defaulting to what
> seems to be packaging conventions.
>
> What do you think?
>
> CCing Ben, Scarlett and Bruno, feedback appreciated.

The other option is: If the local copy of it exists, go ahead with
trying to use that, otherwise try to find a system wide copy.

That way developers, your Android builds, etc. can initialize the
submodule and go ahead as they do now - but it doesn't trouble
packagers or the CI system who provide it through their conventional
means.

>
> Thanks,
>   Holger

Cheers,
Ben

>
> [1]
> https://sysadmin.kde.org/tickets/index.php?page=tickets&act=view&id=BJR-9730