Re: [PATCH] Makefile: use sha1collisiondetection by default on OSX and Darwin

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Thu, Oct 20 2022, Junio C Hamano wrote:

> Ævar Arnfjörð Bjarmason  <avarab@gmail.com> writes:
>
>> Junio: I see in the meantime you've queued your own
>> https://lore.kernel.org/git/cover-v3-0.9-00000000000-20221020T223946Z-avarab@gmail.com/;
>> which is currently in "seen".

[B.t.w. that link is wrong, I meant
https://lore.kernel.org/git/xmqq35bitooc.fsf@gitster.g/]

> Yes, as I said, I intend to merge it to 'next' in tomorrow's
> pushout, and then fast track all three topics (Peff's "-O0",
> Eric/Ævar's "use git_SHA_CTX abstraction", and "osx-clan uses
> sha1dc") down to 'master'.  As you chose to make this topic hostage
> to the other multi-part topic, which is likely to be slowed down and
> require rerolls for typofixes and possible bikeshedding, by the time
> this topic becomes ready, it is likely that it would already be in
> 'master' and you'd have to rebase on that.
>
> Isn't this step of much higher importance than the other multi-part
> topic?  I do not see why you chose to take it a hostage to the other
> one.  Let's all learn to give priorities to produce sufficiently
> focused fixes that also sufficiently cover important issues.  Frills
> and niceties can come on top later.

I don't see why we're in any rush to get this change down to "master"
(either this [1], or the base [2]), nor your jc/ci-osx-with-sha1dc[3].

Your list in [4] has two fixes for issues on "master" which we should
get there sooner than later.

But the 3rd is just addressing a CI blind spot that we've had for at
least 2 years, and since 2017 if we're talking about the default SHA-1
backend on OSX.

Yes, we had some unportable code sneak in recently, but there's no
reason I can see for why we'd expect that to happen tomorrow. It's been
one such issue from 2017 until now, so at this rate we should expect the
next one in 2027, not next week :)

In any case, I figured you might want to fast-track it anyway, or
whatever, which is why I crafted this series to give you easy options
given your [4]. Namely (and in no particular order):

A. You can queue the base topic[2] and this [1] on top of "seen" and
   your jc/ci-osx-with-sha1dc and they won't conflict.

B. This applies directly on "master" if you peel off the first hunk. If
   you wanted this faster than the "doc" change it could be queued like
   that, and we could fix the docs later.

C. You could eject your [3] and we could let this simmer at the normal
   rate, but that's assuming the "no rush" outlined above.

D. You could proceed with your [3], and I can eventually rebase on top
   of it (we'll probably want to undo the nothing-to-do-with-SHA-1
   change, presumably?)

E. You don't need to pick this up at all at this time. Nothing's broken
   now that hasn't been broken for the years by us not using DC_SHA1 on
   OSX by default.

1. https://lore.kernel.org/git/patch-1.1-1f4e39be97b-20221020T225305Z-avarab@gmail.com/
2. https://lore.kernel.org/git/cover-v3-0.9-00000000000-20221020T223946Z-avarab@gmail.com/
3. https://lore.kernel.org/git/xmqq35bitooc.fsf@gitster.g/
4. https://lore.kernel.org/git/xmqqtu3yqhm2.fsf@gitster.g/