Re: execution of rules in included Makefiles

[Paul Smith]

On Tue, 2010-11-09 at 17:43 -0500, Chris Cross wrote:
> The "Testing" line above is from a rule in Makefile.gen that generates
> source used in the outer makefile and before that is the rule I added
> to make the target directory. What I see from using --debug=v is that
> rule being executed before "Considering target file `all'", where
> `all' is the first rule in the outer Makefile.

I don't recall if I replied to this or not.

At any rate, if you see things like this it almost invariably means that
somehow, those targets are being rebuilt as a side-effect of trying to
rebuild all the included files.

For example, if your makefile has automatically generated dependencies,
like:
        include foo.d

and you have a rule that creates foo.d and foo.o at the same time and
from the same set of prerequisites:

        %.o %.d : %.c
                ...

then whenever you invoke your "make" and foo.d is determined to be out
of date, make will rebuild it first and re-exec itself, to read the
newest dependency information.

This is just an example of course: there could be multiple reasons.

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