Conditional dependency with make/gmake

Question

Is there a way to direct make/gmake to act upon conditional dependencies?

I have this rule in place:

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
  $(CPPC) -c $(FLAGS_DEV) $< -o $@

In the general case, every .cpp file has a corresponding .h file; however there are a few exceptions. Is there a way to achieve "depend on this if it exists" with gmake? Failing that, is there a best practice for this type of setup?

Thanks in advance; Cheers!

Update: I'm using GCC

Answer 1

A better way to do this, is to actually determine the dependencies of the cpp files with gcc -MM and include them in the makefile.

SRCS = main.cpp other.cpp
DEPS = $(SRCS:%.cpp=$(DEP_DIR)/%.P)

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
  $(CPPC) -c $(FLAGS_DEV) $< -o $@

$(DEP_DIR)/%.P: $(SRC_DIR)/%.cpp
  $(CPPC) -MM $(FLAGS_DEV) -MT $(OBJ_DIR)/$*.o -MP -MF $@ $<

-include $(DEPS)