fix: support :LspRestart without arguments #3895

Problem:
After the refactoring in e4d1c8b for Neovim 0.11.2 this command now
requires an argument.

Solution:
Restore the previous behaviour where `:LspRestart` defaults to
restarting all active servers.

Author: toupeira

README.md

@@ -154,7 +154,7 @@ Most of the time, the reason for failure is present in the logs.
 * `:LspInfo` (alias to `:checkhealth vim.lsp`) shows the status of active and configured language servers.
 * `:LspStart <config_name>` Start the requested server name. Will only successfully start if the command detects a root directory matching the current config.
 * `:LspStop [<client_id_or_name> ...]` Stops the given server(s). Defaults to stopping all servers active on the current buffer. To force stop add `++force`
-* `:LspRestart [<client_id_or_name> ...]` Restarts the given client(s), and attempts to reattach to all previously attached buffers.
+* `:LspRestart [<client_id_or_name> ...]` Restarts the given client(s), and attempts to reattach to all previously attached buffers. Defaults to restarting all active servers.
 
 ## Contributions
 

doc/lspconfig.txt

@@ -93,7 +93,8 @@ servers: >vim
 
 :LspRestart [client_id] or [config_name] ...                     *:LspRestart*
 Restarts the clients with the given client-ids or config names, and attempts
-to reattach to all previously attached buffers.
+to reattach to all previously attached buffers. Defaults to restarting all
+active servers.
 
 ==============================================================================
 SERVER CONFIGS                                        *lspconfig-configurations*

plugin/lspconfig.lua

@@ -120,25 +120,37 @@ if vim.version.ge(vim.version(), { 0, 11, 2 }) then
   })
 
   api.nvim_create_user_command('LspRestart', function(info)
-    for _, name in ipairs(info.fargs) do
+    local clients = info.fargs
+
+    -- Default to restarting all active servers
+    if #clients == 0 then
+      clients = vim
+        .iter(vim.lsp.get_clients())
+        :map(function(client)
+          return client.name
+        end)
+        :totable()
+    end
+
+    for _, name in ipairs(clients) do
       if vim.lsp.config[name] == nil then
-        vim.notify(("Invalid server name '%s'"):format(info.args))
+        vim.notify(("Invalid server name '%s'"):format(name))
       else
         vim.lsp.enable(name, false)
       end
     end
 
     local timer = assert(vim.uv.new_timer())
     timer:start(500, 0, function()
-      for _, name in ipairs(info.fargs) do
+      for _, name in ipairs(clients) do
         vim.schedule_wrap(function(x)
           vim.lsp.enable(x)
         end)(name)
       end
     end)
   end, {
     desc = 'Restart the given client(s)',
-    nargs = '+',
+    nargs = '*',
     complete = complete_client,
   })