lsp: add client/registerCapability handler (#13780)

Until we support dynamicRegistration, we should handle the client/registerCapability in core. There are still some language servers that send this request despite dynamicRegistration not being registered client-side (we got an upstream fix for the node ones, but this depends on them bumping vscode-languageserver-node).

1 files changed, 12 insertions, 0 deletions

diff --git a/runtime/lua/vim/lsp/handlers.lua b/runtime/lua/vim/lsp/handlers.lua
index 87f35363b1..b4a1eff316 100644
--- a/runtime/lua/vim/lsp/handlers.lua
+++ b/runtime/lua/vim/lsp/handlers.lua
@@ -97,6 +97,18 @@ M['window/showMessageRequest'] = function(_, _, params)
   end
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#client_registerCapability
+M['client/registerCapability'] = function(_, _, _, client_id)
+  local warning_tpl = "The language server %s triggers a registerCapability "..
+                      "handler despite dynamicRegistration set to false. "..
+                      "Report upstream, this warning is harmless"
+  local client = vim.lsp.get_client_by_id(client_id)
+  local client_name = client and client.name or string.format("id=%d", client_id)
+  local warning = string.format(warning_tpl, client_name)
+  log.warn(warning)
+  return vim.NIL
+end
+
 --@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_codeAction
 M['textDocument/codeAction'] = function(_, _, actions)
   if actions == nil or vim.tbl_isempty(actions) then