Support for *global* references-listing

[ELLIOTTCABLE]

Hi!

I didn't see any Issues open for "Find All References" / global-references (⌥⇧F12).

When I invoke that feature of VSCode, at the moment, it only shows references in the current file. (For comparison, the Vim equivalent is vim.lsp.buf.references().)

I'd love to see proper support for whole-project references to a given identifier. This is probably a long-term goal.

As an example, here's the request/response for the currently-implemented file-only textDocument/references implementation:

[Trace - 3:11:24 PM] Sending request 'textDocument/references - (36)'.
Params: {
    "textDocument": {
        "uri": "file:///home/elliott.cable/code/melange/jscomp/core/js_dump_program.ml"
    },
    "position": {
        "line": 127,
        "character": 11
    },
    "context": {
        "includeDeclaration": true
    }
}


[Trace - 3:11:24 PM] Received response 'textDocument/references - (36)' in 1ms.
Result: [
    {
        "uri": "file:///home/elliott.cable/code/melange/jscomp/core/js_dump_program.ml",
        "range": {
            "start": {
                "line": 127,
                "character": 4
            },
            "end": {
                "line": 127,
                "character": 21
            }
        }
    }
]

[ulugbekna]

This will only be fixed when merlin adds support for global reference search. This is on the merlin’s roadmap, AFAIK.

[NoahTheDuke]

Given that Merlin now supports project-wide references, and since #1233, looks like if you build your project with @ocaml-index, then this works out of the box.

[voodoos]

I recommend running dune build @ocaml-index --watch while developing for projects that don't cost too much to index. Then the stand Find All References query in most client should work fine 🙂

I will let you close the issue if that works for you.

[ELLIOTTCABLE]

I don't have an active OCaml project to test this on right now, but I'll definitely keep that in mind. This sounds awesome; I'm really glad to see all your hard work finally land! <3