Coc.nvim: Optionally allow extra client capabilities (semanticHighlight)

[mellery451]

Is your feature request related to a problem? Please describe.
not a problem - just extra capabilities: In order to use the semantic highlighting provided by clangd (9), extra capabilities support is needed - see: https://github.com/jackguo380/vim-lsp-cxx-highlight/issues/14

Describe the solution you'd like
I'm not sure I know the best way to support this - maybe allow extra config params for capabilities OR allow other plugins to register extra capabilities?

Describe alternatives you've considered
Right now I run both ccls and clangd...the former is just for highlighting. I like the features of clangd and would prefer to just run that one.

Additional context
The issue referenced above has some links to other LSP client implementations

Thank you.

[chemzqm]

Create extension is the best way to make use of extra language server capabilities

[fannheyward]

Maybe coc-clangd can add this, I'll look into it.

[purpleP]

@chemzqm https://github.com/autozimu/LanguageClient-neovim/pull/954
I don't know if you're aware of it, but microsoft apparently created extension for LSP that provides semantic highlights. It's already used by vscode and language-client-neovim is implemented it already. It's a great feature, so maybe this issue needs to be reopened?

[mellery451]

@purpleP -- I believe @fannheyward added support for semantic-highlight to https://github.com/clangd/coc-clangd already - It works quite well. See the readme for more information.

[purpleP]

@mellery451 It's a general feature that wil be supported by most language servers.
Why are you mentioning clangd extension?

You need to have a code that will send requests to language server on each change to get changes in highlights etc etc. This needs to be done by coc not by each extension.

[chemzqm]

This needs to be done by coc not by each extension.

Yes

[fannheyward]

This needs to be done by coc not by each extension.

Yes, but semanticHighlighting, or new called semanticTokens protocol has not finished yet, it's in proposed state. https://github.com/microsoft/vscode-languageserver-node/blob/master/protocol/src/protocol.semanticTokens.proposed.ts We will add it when it finished.

[Congee]

@fannheyward linked died. Here's a permalink https://github.com/microsoft/vscode-languageserver-node/blob/d67b9004b2fb25e8f738e0a7bb67ecd5ad6e5911/protocol/src/common/protocol.semanticTokens.proposed.ts