qmake can't tell which Qt QML modules were part of the build

When building Qt modules, you can check in qmake if the correct module is part of this build and error/react accordingly. However, this only works for C++ libraries, a similar functionality should be added for QML imports.

For example,

qtHaveModule(QtQuick.Controls): foo

blocks should be active only when the QtQuick.Controls import was built and installed. (A more conventional name like "controls" would also be acceptable if the caps and '.' are a problem.)