[Development] Optional Qt module dependencies (was: RE: qtsystems doesn't compile...)

[alex.blasche at nokia.com]

>-----Original Message-----
>From: development-bounces+alex.blasche=nokia.com at qt-project.org
>[mailto:development-bounces+alex.blasche=nokia.com at qt-project.org] On
>Behalf Of ext Rohan McGovern

>Incidentally it's rather dangerous to do this kind of
>
>  contains(QT_CONFIG,some_module):QT+=some_module
>
>...behavior nowadays.  In Qt4, QT_CONFIG would be decided at configure
>time, but in Qt5 it can be changed when you qmake additional modules.
>
>In other words, if you test contains(QT_CONFIG,some_module) in your Qt5
>module, you've made your build behavior implicitly depend on the order in
>which the user happened to run `qmake' over the qt5 modules, which is
>largely undefined.  e.g. if you are doing a `make -j20' in qt5.git, the
>qmakes are also parallelized, and your result might flipflop between
>builds.

Surely there must be a way of enforcing dependencies between Qt modules. How would somebody create such a dependency? Is it a matter of mentioning it in sync.profile? Note that the dependency might be platform specific on and currently I don't see a way of specifying it in syn.profile.

--
Alex