When I compile a module that depends on other modules I've compiled previously I have to specify the --module-path <directory> option. This makes modules I depend on visible.
But at the same time I would also like to make some non-modular Jar files visible. However if don't make them automatic modules and just specify the --class-path some.jar right next to --module-path <directory>, then javac seems to ignore the claspath and throws "package yyy not found" and other "not found" errors.
I can understand that using --class-path and --module-path at the same (compile) time is illegal, but javac does not warn me against it in any way.