Re: [PATCH] test_bitmap_hashes(): handle repository without bitmaps

[Jeff King <peff@peff.net>]

On Fri, Nov 05, 2021 at 03:11:11PM -0400, Taylor Blau wrote:

> > I wonder how you found it.  Diagnosing a repository that did not
> > seem healthy?  What I am getting at is if we want a new option to
> > make a plumbing command, other than the test-tool, that calls this
> > function, as the latter is usually not deployed in the field.
> 
> I would not be surprised if this was discovered via Coverity, or by
> manual inspection. Peff and I have been merging a slew of releases from
> your tree into GitHub's fork and so have been reading code in the more
> recently changed areas.

It was Coverity in this case. I haven't actually used the name-hash
dumper for any real-world debugging.

> On the test-tool vs. plumbing thing: I think there are some compelling
> reasons in either direction. There's no *good* home for these in our
> current set of plumbing tools. E.g., the closest example we have is `git
> rev-list --test-bitmap <rev>`, which is kind of ugly. When we needed
> these new inspection tools for some of the newer bitmap-related tests,
> adding them via the test-helper suite was a conscious choice to not
> build on the ugliness of `--test-bitmap`.
> 
> But on occasion these test-tool things are useful to have "in the
> field", as you say. It's rare enough that I usually just clone a copy of
> our fork as needed and build it when I do find myself reaching for
> test-helpers.

Yeah, I could see arguments both ways on such tools (not just bitmaps,
but other "debug this binary format" tools like read-midx and
read-graph). I'm content to leave it as-is until I come across more
in-the-field cases where those tools would be useful. Half the time I
end up in a debugger anyway. ;)

-Peff