To ease development with multiple QML modules, we'll collect the set of dependencies (if they were set with the TARGET syntax), and write their import paths into a qt.conf file. This allows users to work on multi-module projects, without having to manually fiddle with the engines import path when locally runnig their executables or tests. This is especially useful in the case of tests, where there normally isn't a separate deploy step (which could take care of setting up the import paths). There is (currently) no way to provide two different configurations to two binaries in the same directories, as we can only have one qt.conf file in any given place. Resolve this by merging the import paths. To enable this, we safe the list of dependency targets as a directory property, and do a deferred write-out of the qt.conf file. The feature is currently limited to direct dependencies This feature requires CMake 3.19, as we otherwise can't set directory properties on the build directory. [ChangeLog][QML][qt_add_qml_module] When using CMake >= 3.19, qt_add_qml_module now creates a qt.conf file in the build directory next to each binary. This sets up import paths for targets passed to DEPENDENCIES and IMPORTS with the new TARGET option. Fixes: QTBUG-122987 Change-Id: Ic30e6ae2b58c6c5916978ca200d5f24564314e7e Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>