On Fri, Aug 26, 2022 at 09:46:54AM -0700, Junio C Hamano wrote: > Jeff King <peff@xxxxxxxx> writes: > > >> But the fix here isn't to delete unused.cocci, but to hold off on the > >> UNUSEwork D() patches until we figure out how to make coccinelle jive with > >> them. > > > > Yeah, my general skepticism and disappointment above notwithstanding, > > this seems like the best path forward from here. I tried a few other > > tricks (like --macro-file and --iso-file), but if its parser chokes, I > > don't think there's much we can do about it. Even if we wrote a patch to > > coccinelle itself (and I have no interest in doing that myself), it > > would take a while to become available. > > If it is just a single unused.cocci, I would actually think removing > it would be a much better path forward. UNUSED() that renames to > help folks without checking compilers would help noticing bad code > much earlier than unused.cocci many contributors are not running > themselves anyway. Here is another reason for the removal of 'unused.cocci': it's very costly to apply that semantic patch to the whole code base. make SPATCH_BATCH_SIZE=32 contrib/coccinelle/unused.cocci.patch takes 440s on my machine, whereas the second slowest 'object_id.cocci' takes only 56s [1]. Applying 'unused.cocci' to some of our source files individually takes well over a minute: $ time spatch --all-includes --sp-file contrib/coccinelle/unused.cocci builtin/log.c warning: Can't find macro file: /usr/local/bin/lib/coccinelle/standard.h warning: Can't find default iso file: /usr/local/bin/lib/coccinelle/standard.iso HANDLING: builtin/log.c Note: processing took 83.1s: builtin/log.c real 1m23.083s user 1m22.983s sys 0m0.033s $ time spatch --all-includes --sp-file contrib/coccinelle/unused.cocci builtin/rebase.c warning: Can't find macro file: /usr/local/bin/lib/coccinelle/standard.h warning: Can't find default iso file: /usr/local/bin/lib/coccinelle/standard.iso HANDLING: builtin/rebase.c Note: processing took 83.2s: builtin/rebase.c real 1m23.223s user 1m23.156s sys 0m0.017s In my opinion the benefits of having 'unused.cocci' clearly do not justify the costs. [1] https://public-inbox.org/git/20220824113901.GD1735@xxxxxxxxxx/
