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

Ævar Arnfjörð Bjarmason wrote:

On Fri, Jul 02 2021, Felipe Contreras wrote:

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Ævar Arnfjörð Bjarmason wrote:

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On Wed, Jun 30 2021, Felipe Contreras wrote:

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Ævar Arnfjörð Bjarmason wrote:

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Even if you don't care about the end result or making git easier to hack
on for people who don't share your setup,

I don't know about Junio, I do want to make git easier to hack for
people that don't share my setup, but I would like to know what that
setup is.

I think all of this is covered in detail upthread.

From [1] I understand some systems have a problem clobbering a binary
that is being run. So if you are running a test that is using a binary
that you are rebuilding at the same time, you get an error.

OK.

I still don't see why anyone would want to rebuild the binary in the
middle of running tests. The result of the tests is only meaningful for
a particular build. This is what I don't get. I get that you want to do
this, what I don't get is *why*.

This is mostly covered upthread & in the linked thread(s), but as
summary / elaboration:

 1. Running the tests on some of these machines takes 30-45 minutes. A
    common use-case is firing off a test run to see how bright the
    dumpster fire is that day, noticing an early failure, and inspecting
    it manually.

    Then while the rest of the full run is underway I'd like to
    re-compile and e.g. add some printf debugging guarded by a getenv()
    to some isolated code I'm poking, it's nice if the full test run
    isn't invalidated by that.

    Keep in mind that it takes 30-45 minutes because it's *slooooooow*,
    so "just use another workdir" isn't a viable option. I'm also going
    to wait 10-20 minutes for another full recompile in that workdir
    (and now the concurrent test run takes more than an hour).

OK. If you are careful enough that makes sense.

 2. We have bugs in the test suite that e.g. leave orphaned git-daemon
    background processes on these platforms.

    Yes that should be fixed, but fixing it is annoying when you can't
    even recompile and run other (even more broken) tests due to the bug
    you're trying to fix.

Yeah, that's a separate issue.

 3. You're assuming that the only thing I might want to use the built
    git for is the tests.

Not really.

 4. I think you/Junio/Jeff (although maybe less so in Jeff's case) are
    taking this axiom that thou shalt not recompile during tests as an
    absolute.

Just like in language I'm not a prescriptivist in workflows either. The
fact that I don't recompile during tests doesn't mean I would presume to
dictate to others what they should do.

You know more about your setup than me.

I think you've also said something to the effect that the 3rd party tool
should be the thing doing the in-place-rename if needed, fair
enough.

But claiming that it's both an external implementation detail (so it
could do an in-place rename, or not), and also maintaining that we can't
do in-place rename ourselves because doing so would enable bad thing XYZ
to happen (i.e. this concurrent test thing), seems like a case of
wanting to have your cake and eat it too.

I never claimed we can't do in-place rename ourselves, I only said that
I did not see the point. And to be clear the fact that I don't see it
doesn't mean it isn't here.


Now I see why you want this and I suppose for this particular case only
it does make sense to do the renaming. But it still seems like a wart to
me. If the build system supported out-of-tree builds there would be no
need for us to do this manually in the Makefile, correct?

But yeah, for now I suppose there's no better alternative.

-- 
Felipe Contreras