1 files changed, 51 insertions, 49 deletions

diff --git a/runtime/lua/vim/lsp.lua b/runtime/lua/vim/lsp.lua
index 8403aa0ee6..c6d6c8a0cd 100644
--- a/runtime/lua/vim/lsp.lua
+++ b/runtime/lua/vim/lsp.lua
@@ -195,10 +195,13 @@ end
 --- Predicate used to decide if a client should be re-used. Used on all
 --- running clients. The default implementation re-uses a client if name and
 --- root_dir matches.
---- @field reuse_client fun(client: vim.lsp.Client, config: table): boolean
+--- @field reuse_client fun(client: vim.lsp.Client, config: vim.lsp.ClientConfig): boolean
 ---
 --- Buffer handle to attach to if starting or re-using a client (0 for current).
 --- @field bufnr integer
+---
+--- Suppress error reporting if the LSP server fails to start (default false).
+--- @field silent? boolean
 
 --- Create a new LSP client and start a language server or reuses an already
 --- running client if one is found matching `name` and `root_dir`.
@@ -246,19 +249,25 @@ function lsp.start(config, opts)
 
   for _, client in pairs(all_clients) do
     if reuse_client(client, config) then
-      lsp.buf_attach_client(bufnr, client.id)
-      return client.id
+      if lsp.buf_attach_client(bufnr, client.id) then
+        return client.id
+      end
     end
   end
 
-  local client_id = lsp.start_client(config)
+  local client_id, err = lsp.start_client(config)
+  if err then
+    if not opts.silent then
+      vim.notify(err, vim.log.levels.WARN)
+    end
+    return nil
+  end
 
-  if not client_id then
-    return -- lsp.start_client will have printed an error
+  if client_id and lsp.buf_attach_client(bufnr, client_id) then
+    return client_id
   end
 
-  lsp.buf_attach_client(bufnr, client_id)
-  return client_id
+  return nil
 end
 
 --- Consumes the latest progress messages from all clients and formats them as a string.
@@ -339,7 +348,7 @@ function lsp._set_defaults(client, bufnr)
       and is_empty_or_default(bufnr, 'keywordprg')
       and vim.fn.maparg('K', 'n', false, false) == ''
     then
-      vim.keymap.set('n', 'K', vim.lsp.buf.hover, { buffer = bufnr })
+      vim.keymap.set('n', 'K', vim.lsp.buf.hover, { buffer = bufnr, desc = 'vim.lsp.buf.hover()' })
     end
   end)
   if client.supports_method(ms.textDocument_diagnostic) then
@@ -420,16 +429,18 @@ end
 
 --- Starts and initializes a client with the given configuration.
 --- @param config vim.lsp.ClientConfig Configuration for the server.
---- @return integer|nil client_id |vim.lsp.get_client_by_id()| Note: client may not be
---- fully initialized. Use `on_init` to do any actions once
---- the client has been initialized.
+--- @return integer? client_id |vim.lsp.get_client_by_id()| Note: client may not be
+---         fully initialized. Use `on_init` to do any actions once
+---         the client has been initialized.
+--- @return string? # Error message, if any
 function lsp.start_client(config)
-  local client = require('vim.lsp.client').create(config)
-
-  if not client then
-    return
+  local ok, res = pcall(require('vim.lsp.client').create, config)
+  if not ok then
+    return nil, res --[[@as string]]
   end
 
+  local client = assert(res)
+
   --- @diagnostic disable-next-line: invisible
   table.insert(client._on_exit_cbs, on_client_exit)
 
@@ -437,31 +448,7 @@ function lsp.start_client(config)
 
   client:initialize()
 
-  return client.id
-end
-
---- Notify all attached clients that a buffer has changed.
----@param _ integer
----@param bufnr integer
----@param changedtick integer
----@param firstline integer
----@param lastline integer
----@param new_lastline integer
----@return true?
-local function text_document_did_change_handler(
-  _,
-  bufnr,
-  changedtick,
-  firstline,
-  lastline,
-  new_lastline
-)
-  -- Detach (nvim_buf_attach) via returning True to on_lines if no clients are attached
-  if #lsp.get_clients({ bufnr = bufnr }) == 0 then
-    return true
-  end
-  util.buf_versions[bufnr] = changedtick
-  changetracking.send_changes(bufnr, firstline, lastline, new_lastline)
+  return client.id, nil
 end
 
 ---Buffer lifecycle handler for textDocument/didSave
@@ -505,11 +492,18 @@ local function text_document_did_save_handler(bufnr)
   end
 end
 
+--- @type table<integer,true>
+local attached_buffers = {}
+
 --- @param bufnr integer
---- @param client_id integer
-local function buf_attach(bufnr, client_id)
+local function buf_attach(bufnr)
+  if attached_buffers[bufnr] then
+    return
+  end
+  attached_buffers[bufnr] = true
+
   local uri = vim.uri_from_bufnr(bufnr)
-  local augroup = ('lsp_c_%d_b_%d_save'):format(client_id, bufnr)
+  local augroup = ('lsp_b_%d_save'):format(bufnr)
   local group = api.nvim_create_augroup(augroup, { clear = true })
   api.nvim_create_autocmd('BufWritePre', {
     group = group,
@@ -548,7 +542,14 @@ local function buf_attach(bufnr, client_id)
   })
   -- First time, so attach and set up stuff.
   api.nvim_buf_attach(bufnr, false, {
-    on_lines = text_document_did_change_handler,
+    on_lines = function(_, _, changedtick, firstline, lastline, new_lastline)
+      if #lsp.get_clients({ bufnr = bufnr }) == 0 then
+        return true -- detach
+      end
+      util.buf_versions[bufnr] = changedtick
+      changetracking.send_changes(bufnr, firstline, lastline, new_lastline)
+    end,
+
     on_reload = function()
       local params = { textDocument = { uri = uri } }
       for _, client in ipairs(lsp.get_clients({ bufnr = bufnr })) do
@@ -559,6 +560,7 @@ local function buf_attach(bufnr, client_id)
         client:_text_document_did_open_handler(bufnr)
       end
     end,
+
     on_detach = function()
       local params = { textDocument = { uri = uri } }
       for _, client in ipairs(lsp.get_clients({ bufnr = bufnr })) do
@@ -571,7 +573,9 @@ local function buf_attach(bufnr, client_id)
         client.attached_buffers[bufnr] = nil
       end
       util.buf_versions[bufnr] = nil
+      attached_buffers[bufnr] = nil
     end,
+
     -- TODO if we know all of the potential clients ahead of time, then we
     -- could conditionally set this.
     --      utf_sizes = size_index > 1;
@@ -597,16 +601,14 @@ function lsp.buf_attach_client(bufnr, client_id)
     log.warn(string.format('buf_attach_client called on unloaded buffer (id: %d): ', bufnr))
     return false
   end
-  -- This is our first time attaching to this buffer.
-  if #lsp.get_clients({ bufnr = bufnr, _uninitialized = true }) == 0 then
-    buf_attach(bufnr, client_id)
-  end
 
   local client = lsp.get_client_by_id(client_id)
   if not client then
     return false
   end
 
+  buf_attach(bufnr)
+
   if client.attached_buffers[bufnr] then
     return true
   end