How to prepend all filenames on the list with common path?

CMake 3.12 added list transformers – one of these transformers is PREPEND. Thus, the following can be used inline to prepend all entries in a list:

list(TRANSFORM FILES_TO_TRANSLATE PREPEND ${CMAKE_CURRENT_SOURCE_DIR})

…where FILES_TO_TRANSLATE is the variable name of the list.

More information can be found in the CMake documentation.