feat: migrate to vim.lsp.config #3659

Problem:
Nvim 0.11 has vim.lsp.config, which mostly replaces the legacy
nvim-lspconfig "framework".

Solution:
Migrate all configs to `lsp/*` variants. The old configs in
`lua/lspconfig/` are "frozen".

The new configs include these changes:
- `commands` field became raw calls to
  `vim.api.nvim_buf_create_user_command` inside `on_attach`.
- `root_dir` became:
  - `root_markers` whenever the file list was simple didn't need to mach `*`
  - if the logic was complicated, or needed to match something like
    '\*.c', it was defined as a vim.lsp.Config `root_dir` callback.
- `on_config_change` became `before_init`. I don't actually know if this
  is the correct approach, but looking around the documentation of
  `nvim-lspconfig` a saw that it was defined as the function that gets
  called as soon as the config have `root_dir`, and so I thought
  `before_init` might be the closest alternative.
- `docs.description` became a luadoc `@brief` docstring.
- `single_file_support = false`?

Co-authored-by: Aliou Diallo <aliou@users.noreply.github.com>
Co-authored-by: Justin M. Keyes <justinkz@gmail.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/lsp/rls.lua b/lsp/rls.lua
new file mode 100644
index 00000000..c849a2f2
--- /dev/null
+++ b/lsp/rls.lua
@@ -0,0 +1,33 @@
+---@brief
+---
+---https://github.com/rust-lang/rls
+--
+-- rls, a language server for Rust
+--
+-- See https://github.com/rust-lang/rls#setup to setup rls itself.
+-- See https://github.com/rust-lang/rls#configuration for rls-specific settings.
+-- All settings listed on the rls configuration section of the readme
+-- must be set under settings.rust as follows:
+--
+-- ```lua
+-- vim.lsp.config('rls', {
+--   settings = {
+--     rust = {
+--       unstable_features = true,
+--       build_on_save = false,
+--       all_features = true,
+--     },
+--   },
+-- })
+-- ```
+--
+-- If you want to use rls for a particular build, eg nightly, set cmd as follows:
+--
+-- ```lua
+-- cmd = {"rustup", "run", "nightly", "rls"}
+-- ```
+return {
+  cmd = { 'rls' },
+  filetypes = { 'rust' },
+  root_markers = { 'Cargo.toml' },
+}