Quote module/function/record names in completion, signature help

[the-mikedavis]

This improves the display of signature help and fixes label (and edit) values for completions of functions or record names that need quoting, for example #'basic.publish'{} from the Rabbit codebase or calling a function on an Elixir module from Erlang.

Also included is a refactor of base_db::to_quoted_string to return Cow<str> instead, avoiding allocation in the common case that an identifier doesn't need quoting. This saves a few unnecessary allocations.

[robertoaloi]

Thanks! Would it make sense to add a testcase for the completion or the signature help showcasing the change?

[the-mikedavis]

Good call! I added snapshot tests for completion and signature help. While looking at tests I noticed that completion seems to not work for remote modules that need quoting, for example functions on a Elixir.<ModuleName> module. I can look into that too but I think it will be separate from these changes

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[robertoaloi]

Amazing, thanks for this!
Not related to this PR, but we should consider change our general approach around names. Right now, we have to explicitly perform the quoting every time, something that (as you noticed) is easy to forget. Ideally, we'd have a central solution for it.

We discussed briefly with @michalmuskala and we're currently using the Name type for both variables and atoms, two entities with different requirements. A possibility would be to split the type definition, which would then make it possible to enforce correctness and avoid passing raw strings around.

[facebook-github-bot]

@robertoaloi merged this pull request in 7af8893.