(Note: I'm not the Debian `make' package maintainer, just a random
user.)
On Thu, May 28, 2009 at 11:32:23AM +0200, Francois Gouget wrote:
> # -> make forgot to rebuild the build-foo/rsrc.res intermediate file!
No, make just (rightfully) considered it exists. Your snippet is a
classic example of a buggy makefile wrt parallel make: if you want your
lib.so target to depend on *both* main.o and the generated (via chained
rules) rsrc.res, you need to excplicitly state that, like this:
build-%/rsrc.res: build-%/rsrc.rc build-%/main.o
cat $< >$@ || rm $@
This behavior is documented in several related notes in the Make manual
(I'm sorry I can't cite them right now, but by memory: Chained Rules,
Pattern Intro, and most probably a few others).
(Don't use .SUFFIXES -- it's an old, deprecated way that will just make
your makefiles harder to debug as it has different semantics.)
Also, if I may add, pattern rules are somewhat tricky, especially with
-jN. Do not blindly rely on the fact that make will process the
prerequisites' rules sequentially before running the commands of that
target. Take a look of the short example I've posted some time ago:
<http://permalink.gmane.org/gmane.linux.debian.devel.mentors/33162>
> * Declare the rsrc.res intermediate file as .SECONDARY so that it's
> not necessary to rebuild it in the first place.
If it is really not necessary, then why you've put these rules and
dependencies in the first place?
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