Improve interaction with Jj and change fn to diff-hl-resolved-revision

[dgutov]

Fixes #250

[dgutov]

@whhone Hi!

Aside from test failures, does this change look good for you? Previously you submitted this code change in #248.

I think the proposed keeps buffer-local diff-hl-reference-revision working, but if you had any other such vars which would stop working, please chime in.

[whhone]

This change looks very good to me. Passing a revision just avoids hitting the buffer-local issue.

I also patched and verified it works. Thanks @dgutov !

[dgutov]

Thanks for checking.

A test reminds, though, that this way we might dropping support for buffer-local values of vc-hg-program, for example. Is that an issue?

[whhone]

You are right. buffer-local vc-hg-program does not work after this change. It is indeed not ideal.

[dgutov]

I can revert that part, if that's needed.

Something of note, however, is that the Git implementation, and the newly added Jj one, don't support buffer-local values for their corresponding programs. Should we fix that too?

Maybe we could come up with a shared solution.

[whhone]

I believe JJ and git already respect buffer-local variables since they do not switch to a temp buffer.

For example, you can try setting vc-git-program or vc-jj-program as a buffer-local variable and see if they are being respected.

[dgutov]

Is Git really not affected?

diff-hl-resolved-reference-revision calls vc-git--rev-parse, whose definition is wrapped in with-temp-buffer.

Similarly for vc-jj--process-lines.

you can try setting vc-git-program or vc-jj-program as a buffer-local variable and see if they are being respected

Doesn't seem to have effect after setq-local.

[whhone]

Ops... I did not go into the implementation detail of vc-git--rev-parse and vc-jj--process-lines.

I don't have strong opinion on respecting respecting buffer-local variables or not. I can find workaround in my case. Thanks!

[dgutov]

All right, then I'm merging now.

Open to revisiting this issue later, preferably with a solution that handles vc-git-program as well.