Question

I’ve got a little problem understanding following gmake syntax:

OBJ = foo.o bar.o

$(OBJ): %.o: %.cpp
    $(CC) -c -MMD -MP $(INCLUDES) $(CFLAGS) $< -o $@
    @sed (...create empty targets in file...)

I’m not sure what $(…): %.o: %.cpp does!?

I think it might translate the “%.o: %.cpp” in correct %.cpp dependencies – does it? Google is not much of a help here – it finds just the usual double colon (target::) which is something different!

Any advice? Thanks!

Answer 1

This is a static pattern rule.

$(OBJ) is a list of targets. The %.o : %.cpp means “for each target in the list that matches %.o, it is dependent on %.cpp” (where the % is substituted accordingly).