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, 36 insertions, 0 deletions

diff --git a/lsp/elmls.lua b/lsp/elmls.lua
new file mode 100644
index 00000000..803ce7fa
--- /dev/null
+++ b/lsp/elmls.lua
@@ -0,0 +1,36 @@
+local util = require 'lspconfig.util'
+local api = vim.api
+
+local elm_root_pattern = util.root_pattern 'elm.json'
+
+---@brief
+---
+---https://github.com/elm-tooling/elm-language-server#installation
+--
+-- If you don't want to use Nvim to install it, then you can use:
+-- ```sh
+-- npm install -g elm elm-test elm-format @elm-tooling/elm-language-server
+-- ```
+return {
+  cmd = { 'elm-language-server' },
+  -- TODO(ashkan) if we comment this out, it will allow elmls to operate on elm.json. It seems like it could do that, but no other editor allows it right now.
+  filetypes = { 'elm' },
+  root_dir = function(bufnr, on_dir)
+    local fname = api.nvim_buf_get_name(bufnr)
+    local filetype = api.nvim_buf_get_option(0, 'filetype')
+    if filetype == 'elm' or (filetype == 'json' and fname:match 'elm%.json$') then
+      on_dir(elm_root_pattern(fname))
+      return
+    end
+    on_dir(nil)
+  end,
+  init_options = {
+    elmReviewDiagnostics = 'off', -- 'off' | 'warning' | 'error'
+    skipInstallPackageConfirmation = false,
+    disableElmLSDiagnostics = false,
+    onlyUpdateDiagnosticsOnSave = false,
+  },
+  capabilities = {
+    offsetEncoding = { 'utf-8', 'utf-16' },
+  },
+}