Currently moc rule does not support dependency scanning, so after successful moc file generation it will ignore implicit dependencies in header file.

Although this works in most typical scenarious at least in one case incremental build becomes broken: when using Q_PLUGIN_METADATA() with FILE argument.

When FILE refers to JSON file and latter was updated expected behavior is to regenerate moc file. Since CMake add_custom_command() does not support late dependencies setup, all dependencies should be explicitly listed in DEPENDS section.

https://codereview.qt-project.org/#/c/103876