Emacs 27 compatibility

[dgutov]

There are changes in Emacs master that change the calling convention of xref-show-xrefs-function and add xref-show-definitions-function.

[alexmurray]

Thanks - can you include either a comment in the code or something in the README.md as to where / how the new ivy-xref-show-defs function should be made use of for emacs 27?

[dgutov]

Ah, sorry, I mistyped README instructions.

[dgutov]

Should be good now.

[dgutov]

@alexmurray Oh, and someone would need to update the use-package instructions, I guess. 🤷‍♂️

[alexmurray]

@dgutov ah thanks - I updated both actually in 1a35fc0 to do the right thing by consulting emacs-major-version

[dgutov]

Not sure it's the right thing. Have you tried it? This way, in Emacs 27 other commands (e.g. xref-find-references and project-find-regexp) won't use ivy.

Some users might like it (I probably would), but it seems like a personal choice.

[alexmurray]

I am not running Emacs 27 - I just based it off your original recommendation in the README.md - can you explain a bit more what the change in behaviour is in Emacs 27 in this regard?

[dgutov]

What Emacs 27 did:

• Change the calling convention of xref-show-xefs-function (the first argument is now a function, so we can support revert-bufer).
• Split its job into two variables. One is responsible for showing the results of xref-find-definitions, the other (the old one) - for all other uses.

[alexmurray]

So I have finally upgraded to emacs 27 - I changed the instructions to recommend enabling this for both of the new xref interfaces in Emacs 27. See 3d4c35f.