Need a makefile dependency rule that can handle missing files

Question

We use GNU Make for our system. At the end of our makefiles, we have an include called Makedepends which generates a bunch of .d files using -MM switch on gcc. We then include the .d file for each .cc file using an include $(CXXFILES:.cc=.d) line. But when we delete file or move files, the dependancies step breaks and we have to manually delete the .d files (even a make clean doesn't work because the dependencies fail)

Is there a way to generate these dependency .d files or include these dependency .d files which will gracefully handle a file deletion or relocation?

EDIT: For example: I have serial.cc and the makefiles generate a serial.d file which has a dependency on buffer.h but then I change it so I don't need buffer.h any more and I delete buffer.h. Next time I run make, it will choke because it includes the .d file which still makes serial.o depend on buffer.h.

Answer 1

Two possibilities:

First, can you add a rule to your Makefile to run the dependency step:

.SUFFIXES: .d

%.d::
   makedepend_command_here

If not, then from the Last Resort section of the info page for GNU Make:

For example, when testing a makefile, you might not care if the source files contain real data, only that they exist. Then you might do this:

 %::
         touch $@

to cause all the source files needed (as prerequisites) to be created automatically.

Will this work to create empty .d files for you?

Answer 2

http://make.paulandlesley.org/autodep.html has a description of this exact problem, and a couple of ways around it. The first is a bit misguided, but the "advanced" is essentially spot on.