"First party" LSP written in C3

[giuliano-macedo]

I saw that in #1456 there is this bullet point:

High quality LSP

What is your opinion on implementing one in C3 by using the c3c lexer/parser, and adding to the c3c repo or another repo inside c3lang?

I'm asking this because one of the things I like about go is that gopls is maintained by the go team (thats what I call a "First party" LSP) and AFAIK it uses the same lexer/parser that that the go compiler uses, increasing its correctness.

I've never built an LSP myself, this is just my first thoughts about this, I would love to implement* like this if you think it is a good idea, but I am open to new ideas as well.

*: I can't promise though, it would be a lot of work I think.

I think it could start with these actions (that are the same that helix currently supports) because is a good subset of commonly used LSP actions:

• must:
  • diagnostics → textDocument/publishDiagnostics (notification from server)
  • goto-definition → textDocument/definition
  • goto-declaration → textDocument/declaration
  • goto-type-definition → textDocument/typeDefinition
  • goto-reference → textDocument/references
  • goto-implementation → textDocument/implementation
  • format → textDocument/formatting
  • hover → textDocument/hover
  • textDocument/didChange for codecompletion/error reporting for each keystroke
• nice to have:
  • document-symbols → textDocument/documentSymbol
  • workspace-symbols → workspace/symbol
  • rename-symbol → textDocument/rename
  • completion → textDocument/completion
  • signature-help → textDocument/signatureHelp
  • code-action → textDocument/codeAction
  • document-highlight → textDocument/documentHighlight
  • workspace-command → workspace/executeCommand
  • inlay-hints → textDocument/inlayHint

[chrischtel]

I think a Language Native LSP would be very, very cool!

[lerno]

I would not use the c3c parser, since you want something more lenient for an LSP: it should be caching information and work well with incomplete data and such.