Make it depend on the corresponding Private target of each
dependency. This way, user code can write
find_package(Qt5Gui REQUIRED)
add_executable(hello hello.cpp)
target_link_libraries(hello Qt5::GuiPrivate)
and get the private include directories for both Qt5Core and Qt5Gui.
Don't create the Private target if any of the private include
directories do not exist. This way, if user code uses one of the
targets, CMake will issue an error if the private include directories do
not exist. Unfortunately the error is somewhat cryptic (eg, 'the
"Qt5::CorePrivate" was not found'), but this is still an improvement
over an error at compile time.
This is an improvement on the situation described in QTBUG-37417 using
Modern CMake features.
Change-Id: I034f8216c3ec64d1a3309682456a713cac9bf854
Reviewed-by: Kai Pastor <dg0yt@darc.de>
Reviewed-by: Stephen Kelly <steveire@gmail.com>
8266de089c