On Sun, Mar 12, 2017 at 04:51:19PM +0000, brian m. carlson wrote:
> Yeah, my goal was basically to pass -fsyntax-only, not to produce useful
> object files. My patch does basically require that the user have
> OpenSSL installed, but I do, so it doesn't matter.
>
> I considered after the fact that I might just do something like:
>
> #ifdef SHA1_HEADER
> #include SHA1_HEADER
> #else
> #include "block-sha1/sha1.h"
> #endif
>
> That would be the smallest change, but probably not the best.
Yeah, if there is going to be a fallback it probably ought to be
the internal one.
> > Of course the sha1 header is just one of many such defines. It's the one
> > that is most visible because the result is syntactically valid without
> > it, but anything you compile without the Makefile's CFLAGS may be subtly
> > different than what the Makefile would produce. So arguably the Makefile
> > should be writing out a build-options.h with all of the values, and that
> > should get pulled in by git-compat-util.h.
> >
> > I don't know if we want to go down that rabbit hole or not. I offer it
> > merely as an alternative. I'm OK with your patch as-is if you don't want
> > to dump any more time into it.
>
> I'll take this patch for now and fix it up with the comment I mentioned
> below. If someone wants to improve the situation down the line, then
> they can pick that up.
>
> I assume I can apply your sign-off to the resulting patch?
Yes, it is OK to add my sign-off. The two things I was concerned about
with my patch were:
1. It does introduce an extra shell invocation on every "make", even
if the file does not need to be rebuilt (though it is just one of
many; GIT-BUILD-OPTIONS, etc).
2. I wasn't sure if the dependencies were quite right. I _thought_ we
should pick it up as an auto-dependency, but I don't think that
works because we do our header dependencies as a side effect of the
compile.
So "make" didn't actually know to build hash.h until I made it a
dependency of help.o. Which feels weird and hacky. It's really a
dependency of _anything_ that includes cache.h.
So you may want to dig into that second one to make sure the result is
sane, not racy, etc.
> > +hash.h:
> > + $(QUIET_GEN)echo '#include $(SHA1_HEADER)' >$@+ && \
> > + { cmp $@+ $@ >/dev/null 2>/dev/null || mv $@+ $@; }
>
> I think here we'd want to also "rm -f $@+", so that we don't leave an
> extra file behind if we're up-to-date (which is the common case), much
> like we do for GIT-BUILD-OPTIONS.
Yeah, I agree that would be an improvement.
-Peff