Automatic make dependency generation and "clean"

simopal6 · 11-24-2011, 03:28 AM

Hello,
I recently found out about g++'s ability to automatically generate makefiles and I'm trying to make advantage of it, however I have a small problem; that is, I have:

Code:

# Include dependency files
-include $(DEP_TARGETS)

# Rule for dependency files
%.d:    %.cpp %.h
        $(CXX) $< $(CXXFLAGS) -MMD -MP -c

# Cleaning rule
clean:
        ...

The problem is that, as far as I have understood, if "include" can't find a .d file, it looks for a rule to create it, and applies the rule. This could be ok, however if I want to run "clean" I don't want dependency files to be rebuilt (i.e. objects to be compiled) if they don't exist.

Well, yeah, there probably is no need to "make clean" if no .d/.o files exist, however this kind of annoys me anyway.

Is there any way to perform makefile inclusion conditionally on the rule given from the command-line?

Thanks! :-)

Here are the relevant (I think) parts of my Makefile:

ntubski · 11-25-2011, 12:16 AM

Quote:

Is there any way to perform makefile inclusion conditionally on the rule given from the command-line?

Yes it's possible to do this but there is a better way: remove the the rule to create .d files, just create them when compiling. The .o and .d files always need to be updated at the same time anyway. Furthermore, g++ has the ability to create the depenency file during compilation, saving even more time.

simopal6 · 11-28-2011, 08:54 AM

Thank you very much!
I knew I could update the .d file while compiling, but I just hadn't thought of removing the .d rule in the Makefile

Thanks again!