When building llvm with the lldb useflag, qtcreator detects it and tries to detect its version. However, there is a little snag when llvm-3.7 is installed, see this bug report: https://bugreports.qt.io/browse/QTCREATORBUG-15131 With this bug, qt-creator takes 30 to start. It took me quite some time to figure that qt-creator is actually functioning. The patch for the fix is here: https://github.com/qtproject/qt-creator/commit/97e9f113879ca23d20ab0a5f124aaff9066ffb55 or, in raw form: https://github.com/qtproject/qt-creator/commit/97e9f113879ca23d20ab0a5f124aaff9066ffb55.diff The fix is in qt-creator 3.6 but as the symptoms are really nasty, I propose to add this patch to < 3.5
I just realized that the patch has to be modified in the sense that <QFileInfo> is required as an include to the changed file
3.6.0 is in portage. 3.5.x is not and will never be a stable candidate, so I'm not going to backport the patch, considering that it's for an experimental feature.