I'm using makefiles to convert an internal file format to an XML file which is sent to other colleagues. They would make changes to the XML file and send it back to us (Don't ask, this needs to be this way ;)). I'd like to use my makefile to update the internal files when this XML changes.

So I have these rules:

%.internal: $(DATAFILES)
       # Read changes from XML if any
       # Create internal representation here

%.xml: %.internal
       # Convert to XML here

Now the XML could change because of the workflow described above. But since no data files have changed, make would tell me that file.internal is up-to-date. I would like to avoid making %.internal target phony and a circular dependency on %.xml obviously doesn't work.

Any other way I could force make to check for changes in the XML file and re-build %.internal?