Add node for angle bracket delimited built-in reference

[oxfist]

This PR adds support for syntax such as source <afile>. According to Neovim docs under :h afile, this is valid syntax but the parser currently errors out with this:

[oxfist]

@clason this is a fairly small change to fix an issue that breaks parsing of valid syntax. Are you able to review it? 🙏🏼

[clason]

There's a bunch of unrelated changes in this PR; I'd prefer these to be made separately (if at all).

And I'm not sure that is the correct fix, as these are not filenames. It's better to create a proper node for these constructs.

[oxfist]

I'll remove the unrelated changes and can update the PR to add a new node node for these no problem 👍🏼

[oxfist]

@clason please let me know if this works better, happy to help get this fixed.

[clason]

Yes, that is better. Can you update the queries, too? (And more complex tests?)

[clason]

The issue is that this syntax is valid only in autocommands.

[oxfist]

@clason I'm having trouble getting the highlights to work. I've updated grammar.js with the following:

module.exports = grammar({
    // ...
    builtin_reference: ($) => /<[A-Za-z]+>/,
    // ...
    source_statement: ($) =>
      bang_range_command(
        $,
        "source",
        optional(field("file", choice($.filename, $.builtin_reference)))
      ),
    // ...
});

This makes the tests pass, but then in highlights.scm I added this query, and for some reason the node doesn't have the capture group I've defined:

(autocmd_statement command: (source_statement file: (builtin_reference) @variable.builtin))

I'm able to get the right node type, and even get the proper node highlighted in the Treesitter playground with the query above:

Any help or guidance to figure this out would be very much appreciated! 🙏🏼