With modularized Qt, using QT_CONFIG is dangerous, because the behavior changes depending on the order in which modules are qmake'd. For example, an autotest doing: contains(QT_CONFIG,svg):QT += svg ...will depend on libQtSvg if (and only if) the autotest is qmake'd _after_ qtsvg is qmake'd. This makes the tested functionality unpredictable. Also, if the above example occurs within qtbase, it causes the test to sometimes have a circular dependency: if qtsvg is qmake'd before the test is qmake'd, the test in qtbase depends on qtsvg which depends on qtbase. Tests must avoid functionality tests via QT_CONFIG except where all the tested modules are dependencies of the current module. Usage of QT_CONFIG with qt3support was entirely removed since Qt5 will not retain qt3support. Reviewed-by: Jason McDonald Change-Id: I5a5013b3ec7e1f38fb78864763c9e7586c15e70b