it seems the problem is in implicit make rules.
make thinks QtSingleApplication is produced by qtsingleapplication.cpp and tries to compile the header as well by its implicit rules.
Workaround: make QtSingleApplication header newer and corresponding cpp file
it seems the problem is in implicit make rules. make thinks QtSingleApplication is produced by qtsingleapplication.cpp and tries to compile the header as well by its implicit rules.
Workaround: make QtSingleApplication header newer and corresponding cpp file