Delegate outline generation to Merlin

[Tim-ats-d]

Replacement of the in-house solution for generating outlines by Merlin.

I had to regenerate the tests because merlin and ocaml-lsp don't calculate the positions of elements in the outline in the same way. Fir instance, the y loc was the enclosing location for ocaml-lsp:

let x = object
  method y = 10
(*^^^^^^^^^^^^^*)  
end

While Merlin indicates the exact position:

let x = object
  method y = 10
      (* ^ *)  
end

The PR diff also indicates that several items kind value have changed from 7 to 13. Indeed, Merlin treats instance variables as Values and not as Property like ocaml-lsp does. This change simply means that the icon displayed on the vscode side will be different

Could you please mark this PR has draft? We have to wait for the next Merlin next because we need this patch ocaml/merlin#1936

[xvw]

What a nice PR! Thanks!

[voodoos]

Sometime the result spans multiple lines like the previous one for a. But sometimes the only highlight the character like this one for b. Do you know why ?

I expect for most editors this is not an issue since they only use the start position ? But we might want to be a bit more careful about what we return here...

[voodoos]

There was more to that in the e2e test. The LSP protocol reports 2 locations for outline items: the location of the entire englobing item and the selectionRange that is used when the user clicks the outlines and should select a meaningful identifier. I updated Merlin and this PR to also report these selection ranges.

[xvw]

I guess that the PR can be undrafted yes?

[coveralls]

Pull Request Test Coverage Report for Build 4862

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 14 of 17 (82.35%) changed or added relevant lines in 1 file are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.08%) to 23.384%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
ocaml-lsp-server/src/document_symbol.ml	14	17	82.35%

Files with Coverage Reduction	New Missed Lines	%
lsp/src/types.ml	2	13.08%

Totals
Change from base Build 4858:	-0.08%
Covered Lines:	5979
Relevant Lines:	25569

---

💛 - Coveralls