feat: support standard lsp method for handling source generated content

[sebastianstudniczek]

Starting with roslyn version 5.7.0-1.26217.5 roslyn no longer uses custom lsp methods for handling source generated content.
Official lsp methods from 3.18 version workspace/textDocumentContent and workspace/textDocumentContent/refresh should be used.

LSP Spec https://microsoft.github.io/language-server-protocol/specifications/lsp/3.18/specification/#workspace_textDocumentContent

Related: dotnet/roslyn#83119

[sebastianstudniczek]

Guess we can wait until LSP 3.18 is officialy out

[tris203]

If this method was upstreamed in neovim, would this let us delete this code entirely?

[sebastianstudniczek]

Looks like it, since there is no roslyn specific code. Maybe it's better to try to upstream it right away instead of putting it in this plugin (altough this forces people on stable to wait for new neovim release).

[tris203]

if its small changes, then its possible they would backport

or i would feel more confortable vendoring the upstreamed code exactly

[sebastianstudniczek]

Sounds good, I will create an issue in neovim repo then

[sebastianstudniczek]

Actually there is currently roslyn specific check for buffer name roslyn-source-generated://* so need to check how this can be handled. LSP spec defines schemes (types of content that server can provide) for server capability options so this might be the answer.

EDIT:
Yes, roslyn exposes this value roslyn-source-generated in server_capabilities

vim.api.nvim_create_autocmd("LspAttach", {
  callback = function(ev)
    local client = assert(vim.lsp.get_client_by_id(ev.data.client_id))
    if not client:supports_method("workspace/textDocumentContent") then
      return
    end

    local schemes = assert(vim.tbl_get(client.server_capabilities, "workspace", "textDocumentContent", "schemes"))

[sebastianstudniczek]

Keeping as draft for now for people who need this