I'd like to add a comment here as the actual Qt maintainer. There are valid reasons to split up Qt. E.g. there is at least one app I know of that uses Qt but is not a X app. It would also be nice to split out the development tools that are shipped with Qt., or qtwebkit, the database drivers etc..

In theory they claim that Qt is modular. But their buildsystem is really not meant to split the packages (in contrast to e.g. KDE). I did not find any sane way to do so which isn't either very hacky or will result in writing your own make files (__simple__ patches are welcome though).

However: I cheked the benefit and it looks like that e.g. KDE basically needs everything from Qt; there are even apps that link to libs from the qtlinguist and development tools.

First of all, I'd like to congratulate with you for the great work you have done with KDE packages.
About splitted Qt, it's at least possible to split the library from the demos and the tools. This is done by the Chakra guys for example.
Talking of the Qt library itself, the /src directory contains a src.pro project, which is a sub-dirs project. Maybe it's possible to call "make install" on each subdir separately (to verify).
No way build one time an move the files afterwards?

Trust me, I checked all this before. It's not that easy. What chakra does is just moving the devtools binaries etc. in a separate pacakge but leave everything else (libs) in Qt. I don't really see the benefit here. It only reduces a 35MB package by about 1MB, but increases complexity. Qt-doc is already a separate package.

But as I said: feel free to work on this and if the result is a simple PKGBUILD we can rethink about this.

We also split out the demos and examples. This can be done by patching the toplevel makefile _after_ running configure. Its a simple patch. We didnt update it since 4.5.x afaik and it still applies without problems, so even if it smells hackish it does work fine :)

Here is the patch if you want to take a look:
http://chakra-project.org/svn/packages/testing/qtmod/demosexamples-manual-install.patch

By default Qt does "make install" in every subdir, so you can just remove these lines in the makefile for components you dont want and then run the installation in subpackages.

I think we are talking about different things here. Qt in extra does not have demos, examples nor docs included. Those are in the qt-doc package. And I don't get your patch either; why don't you just these configure options: "-nomake demos -nomake examples -nomake docs"?

For everything else its a little more complicated due to the dependencies between the Qt modules. In fact my patch to that Makefile was quite long. The benefit was low though as only very few packages wont depend on nearly everything. E.g. for KDE it's not worth it.

The agenda was "feel free to work on this", not "is it feasible for me?", and i just added some information how we do it. Now someone can go along with the knowledge gathered here and maybe do something with it.

Of course i know about these options to disable docs, demos etc and that Qt's install targets are a pain ;) The patch just serves the purpose to "keep" the knowledge, so that even unexperienced users can take the PKGBUILD and see how it could be split. All in all, a simple patch or commenting (out) some stuff in the PKGBUILD is the same level of "unclean" and more a matter of personal preference, and i just prefer the patch :)