I use usFunctionEmbedResources() in an external project and end up in the function's last add_custom_command() call. This call is meant to create a post build command that makes the resource compiler append a zip file to a library:
add_custom_command( TARGET ${US_RESOURCE_TARGET} POST_BUILD COMMAND ${resource_compiler} --append $<TARGET_FILE:${US_RESOURCE_TARGET}> ${US_RESOURCE_MODULE_NAME} ${_zip_archive} WORKING_DIRECTORY ${US_RESOURCE_WORKING_DIRECTORY} COMMENT "Appending zipped resources to ${US_RESOURCE_TARGET}" VERBATIM )
The problem is that the command syntax is wrong and causes the resource compiler to stop and print its usage. The resource compiler, when called with "--append" does not expect the module name. The working version skips this parameter:
add_custom_command( TARGET ${US_RESOURCE_TARGET} POST_BUILD COMMAND ${resource_compiler} --append $<TARGET_FILE:${US_RESOURCE_TARGET}> ${_zip_archive} WORKING_DIRECTORY ${US_RESOURCE_WORKING_DIRECTORY} COMMENT "Appending zipped resources to ${US_RESOURCE_TARGET}" VERBATIM )
Whereas I am not sure if this needs a Needs_Core_Modification flag, I'd rather let you know about this change.