So the real problem seems to be that we now not only copy files from the sources, which used to be listed with their relative path, but also generated files, which are listed with an absolute path, due to being referenced via the ${CMAKE_CURRENT_BINARY_DIR} var (given that there seems no other way).

Now what to expect from COPY_FILES? Really always drop the complete path with absolutly referenced files? Usually files created in the build are living at a matching level. So I guess we should see to somehow match the level of the passed _srcdir and drop only the path up to that level, so that it does not matter again if the file was in the src dir or in the matching build dir.

What do you think?