Re: [PATCH] Makefile: add and use the ".DELETE_ON_ERROR" flag

On Wed, Jun 23 2021, Jeff King wrote:

On Wed, Jun 23, 2021 at 09:54:06PM +0200, Ævar Arnfjörð Bjarmason wrote:

quoted

quoted

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".

Yeah, that's a fine reason, too. I'm not entirely clear on what the
problem is, though, or why this is the best solution (I expect you
probably explained it in an earlier thread/series, but if so it went in
one ear and out the other on my end).

On *nix systems you can open a file, and unlink() it in another process,
on Windows this is an error.

AIX has its own variant of this annoying behavior, you can't clobber (or
open for writing) binaries that are currently being run, you can unlink
and rename them though.

So without that "mv $@ $@+" trick you can't recompile if you have a
concurrent test (that you don't care about failing) running, and we have
bugs in our tests where e.g. "git-daemon" gets lost and won't get killed
on that platform, so you can't recompile and test without tracking it
down and killing it.