i've installed qt from cvs (w/ the cvs build by Dan). Then i installed qt-3.0.5. and wanted to play a bit w/ the DB plugins. They don't work. I had to remove the libqt-mt.so.3.1 from the /usr/qt/3/lib/ directory. Making strings libqt-* |grep plugins seems that the hardwired plugins path is to the /var/.../. But that needn't be the problem, instead, it could be the incompatibility of qt 3.1 w/ DB plugins made w/ qt 3.0.5?
qt-3.0.5-r2.ebuild uses mysql, postgresql and odbc USE-flags, sure you have them set (in make.conf or env)?
Well, you should have run emerge clean, that would have removed the older qt-5 ebuild and with it libqt-mt.so.3.1. And then everything would have worked, right? Yes, qt-3.1 my be BIC with 3.0.x now and then (qt-copy being a moving target) and you're not supposed to swap qt's internal plugnis between versions, so it might well be BIC there. I don't think there's an issue here. (BTW apps compiled against qt 3.0.x _do_ run with qt 3.1; just not the other way around. So it's not really BIC.)
I did understand you correctly, removing libqt-mt.so.3.1 fixed all problems right?
I don't think there's still an issue here? QT 3.1.0 (final) and qt 3.0.5 should be frely interchangeable (but don't swap plugin files betwen them :-)