Should handle empty vars: $(if $(filter-out 1,$(words "$(PATH_TO_CHECK)")),$(error spaces found))
That's a good trick, but I wouldn't use the double-quote character (") for that purpose, because it is misleading, as its meaning is overloaded in the shell etc.
I would add some normal text around the variable expansion and a comment for the unwary: # Adding 'pre' and 'post' caters for an empty variable # and also checks for leading and trailing whitespace, # which would otherwise be automatically stripped. $(if $(filter-out 1,$(words pre$(PATH_TO_CHECK)post)),$(error spaces found)) Regards, rdiez
