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

[Mcgovern Rohan (Nokia-MP-Qt/Brisbane)]

Blasche Alex (Nokia-MP-Qt/Brisbane) said:
> >Incidentally I think config tests are overused in various qt5 modules at
> >the moment - qtsystems for example has 6 config tests, all of them
> >non-mandatory, doesn't that give 2**6 => 64 possible build
> >configurations?  Surely it's not intended to actually support them all.
> 
> That's a bit of a trivialisation of the mater. The 95 config tests in qtbase would otherwise be worse ;)
> 

I never said I liked the situation in qtbase :)

> Your statement holds only true if every combination would influence each other.
> qtsystems has three libraries.
> Gconf and contextkit are mutually exclusive and only apply to P&S.  Bluez and udev apply to system information only and wayland for SFW only. Jsondb is the only one applying to all. 
> 
> Also your 64 combinations assume that enabling Bluez related code paths would change for example gconf/contextkit code paths. In most cases enabling one doesn't change anything for the other (jsondb is just about the only exception).
> 

So you're asserting that only certain combinations are relevant, which
is great :)  What's not so great is that they aren't defined.  For
example, we advertise "Ubuntu 10.04 x86 32-bit" as a supported platform,
not "Ubuntu 10.04 x86 32-bit with gconf, contextkit, bluez, udev and
wayland".  Does anybody even know which code paths are enabled in the
CI without going to check the logs?

> Last but not least qtsystems accumulates information from a large variety of system components. It is only natural that it has to do a few more tests than normal.
> 

Yes this is natural. I deliberately picked a module with a lot of config
tests to make this point.