[Build-common-hackers] CFLAGS and implicit rules

[Tom Huckstep]

In the CDBS documentation you assert that in a Makefile CFLAGS should always
be overrideable by a user, so that it doesn't matter that CDBS sets CFLAGS.

My upstream uses implicit make rules to generate the .o's, and in this case
CFLAGS (and CPPFLAGS) is the only way to change make's behaviour.

What changes to the Makefile do you suggest I make so that CFLAGS can be
overridden?

I've thought of "override CFLAGS += $(UPSTREAM_CFLAGS)" but it's not nice. 
Is there a nicer way, short of using explicit rules for each .o?

Please CC me on replys.

Tom