hard-dep for Qt 4.8

[Alexander Neundorf]

On Friday 13 January 2012, Thomas Lübking wrote:
> Am 12.01.2012, 22:50 Uhr, schrieb Ingo Klöcker <kloecker at kde.org>:
> > If you want developers to switch to Qt 4.8 to get the KDE code better
> > tested with this version of Qt then simply ask developers to do so. I
> > see no good reason to force developers to do so.
> 
> I tend to agree that KDE should not add hard deps for "manipulative"
> reasons - that has a very ugly attitude to it.
> 
> On the other hand, Qt 4.8 - while in theory ABI stable - broke quite some
> things, starting at least with the qDeleteAll incident and also including
> the switch to the raster graphicssystem as a default (not to mention that
> mapToGlobal() works, works not. works, works not. works, ...? ;-)
> 
> Those carries a large potential to weakly (but effectively) break (while
> not guaranteed, yet implicit) ABI and therefore should be subject to
> developer testing.
> 
> Does cmake allow to intercept the configuration process and force a
> conditional message (like a weak configuration error) to be confirmed*  to
> inform everyone about those implications and -quite intrusively- recommend
> to build and test against Qt 4.8?

No, it's an error or it's not an error (i.e. a plain message).

Alex