On Tue, Jun 22 2021, Jeff King wrote: > On Tue, Jun 22, 2021 at 07:34:13PM +0200, Ævar Arnfjörð Bjarmason wrote: > >> > That makes me a little sad, but it does leave us with a much cleaner >> > Makefile as a result. So, I'm not really sure how to feel about it. I >> > think in general I would be happy overall to see this picked up. >> > >> > [1]: https://lore.kernel.org/git/YGQdpkHAcFR%2FzNOx@xxxxxxxxxxxxxxxxxxxxxxx/ >> >> Yes, it makes me sad too, but as noted above I think you're right about >> the general case, and so is Jeff in that E-Mail you linked, but it >> doesn't apply to these patches, or my earlier patches. >> >> I'd like us to always have a working binary, but from my understanding >> of Jeff and Junio's position on it it's something they'd like to >> actively prevent, see the discussion around my earlier series. >> >> I.e. from what I gather they view this "your thing is clobbered as it >> builds" as a feature. I.e. it serves to throw a monkey wrench into any >> use of git that may overlap with said build, and they think that's a >> feature. > > Just to be clear, I would be happy to drop the "oops, the tests barf if > you recompile halfway through" feature away if it made things more > robust overall (i.e., if we always did an atomic rename-into-place). I > just consider it the fact that we do clobber to be an accidental feature > that is not really worth "fixing". But if we care about "oops, make was > interrupted and now you have a stale build artifact with a bogus > timestamp" type of robustness, and "the tests barf" goes away as a side > effect, I won't complain. ..and "this behavior is really annoying on one platform we target, and the fix is rather trivial". > I'd like it a lot more if we didn't have to add "mv $@+ $@" to every > rule to get there. In some other projects I've worked on, compilation > happens with a script, like: > > %.o: %.c > ./compile $@ I'd think that supporting e.g. "-o" in the middle of an argument list in such a tool would be more annoying than on the order of a dozen callsites I needed to add this to in the linked series. But yes, we could do it in some helper script too; I actually wrote one that does almost that a while ago for a related use-case, simplifying the "use cmp(1) and replace if different" we have copy/pasted in various places. > and then that "compile" script is generated by the Makefile, and encodes > all of the dependencies of what's in $(CC), $(CFLAGS), and so on (we'd > probably have an update-if-changed rule like we do for GIT-CFLAGS). > > And it also becomes an easy single spot to do that kind of "let's > replaced the output atomically" trick. > > That's a pretty big departure from our current Makefile style, though. > And I don't feel like it buys us a lot. Having a pretty generic and > typical Makefile is nice for people coming to the project (I have > noticed that most people are not well versed in "make" arcana). I still think just doing "&& mv $@+ $@" is the simplest in this case, we already have that in a dozen places in the Makefile, I wanted to add it to a dozen or so more. It's a common pattern already, I'd think if anything applying it uniformly would make things easier to read, even if we didn't get more portability & the ability to run stuff concurrently when you have "make" active as bonus.
