Subject: Re: [PATCH] MIDX: revert the default version to v1

From: Jeff King <[email-masked]>
Date: Thu, 16 Apr 2026 19:27:55 -0400

On Thu, Apr 16, 2026 at 05:12:30PM -0400, Taylor Blau wrote:

> > As a result, writing a midx with Git 2.54-rc2 puts the repository into a
> > state that is unusable with Git 2.53. And this midx write may happen
> > behind the scenes as part of normal operations, like fetch.
> 
> I'm not sure if it's worth mentioning, but I think that it's reasonable
> to say "Git 2.53 and earlier", with the implied lower bound being which
> version first introduced the MIDX. I think it's equally fine as-is,
> though.

Yeah, that is a little more clear. Looks like it's been pushed out to
next already, though.

> > I have a feeling there are probably some gaps in v2 testing in t5319,
> > since we are no longer using v2 for the bulk of the tests. IMHO that is
> > OK to sort out post-release.
> 
> Perhaps, although you could make the opposite argument for v1 MIDXs
> when we previously switched the default to write v2 MIDXs. The format
> differs only in the version field, and the ordering constraints on the
> packs within the MIDX. That area and the compatibility issues here are
> the "interesting" parts to test IMHO.

I think that t5319 specifically writes a few midxs with v1 to test the
ordering constraints. Probably there should now be some v2 specific
tests in the same way. I was hoping you could pick up the pieces there,
post-2.54.

-Peff