[OE-core] Qt in OE-core

[Richard Purdie]

On Tue, 2014-01-07 at 20:23 +0100, Martin Jansa wrote:
> I would like to see qt4 moved from oe-core to meta-qt4.
>
> That would remove the feeling that using oe-core defaults to using qt4
> and it would be consistent with other QT layers:
> 
> meta-qt3
> meta-qt4
> meta-qt5
> 
> oe-core would stay just the "core" and if you need any QT you can select
> which one suits your needs the most (or combination of e.g. qt4+qt5 like
> most people are using now)
> 
> With PACKAGECONFIGs which can list optional dependencies which aren't
> included in the the layer itself it's now easier to have recipe with
> optional qt5 support in oe-core, but qt5 itself in separate meta-qt5.
> 
> Another interesting aspect is that with qt4 we have only 6 recipes in
> openembedded-core/meta/recipes-qt/qt4
> 
> while
> meta-qt5/recipes-qt/qt5 has 25 different recipes (many of them with
> _git.bb variant so 42 in total). And splitting the qt5 recipes (e.g. to
> have only qtbase, qtdeclarative in oe-core and "additional" modules in
> separate meta-qt5) isn't very good, because they are quite tightly
> coupled (so upgrading recipes in meta-qt5 would be in many cases
> incomatible with qtbase version in oe-core and vice-versa).

What dependencies on other layers does meta-qt5 have?

If the policy is all qt5 things into meta-qt5, the risk is a fairly
large set of layer dependencies for meta-qt5.

There is some perception I don't like external layers which isn't true. 

What I do dislike is "dependency creep". If the meta-qt5 isn't usable
without pulling in chunks of meta-oe for example, I'd think that rather
sad and it might as well move to meta-oe at that point.

Also, whilst there are only 6 qt4 recipes in core, they are (at least as
far as I know) the core qt components that people base off so in that
sense we're enabling developers and don't have a ton of "apps" around
they probably wouldn't want to use.

Cheers

Richard