fix(lsp): expose ContentModified error code to callbacks (#15262)

runtime/lua/vim/lsp/rpc.lua

@@ -466,15 +466,12 @@ local function start(cmd, cmd_args, dispatchers, extra_spawn_params)
       -- We sent a number, so we expect a number.
       local result_id = tonumber(decoded.id)
 
-      -- Do not surface RequestCancelled or ContentModified to users, it is RPC-internal.
+      -- Do not surface RequestCancelled to users, it is RPC-internal.
       if decoded.error then
         local mute_error = false
         if decoded.error.code == protocol.ErrorCodes.RequestCancelled then
           local _ = log.debug() and log.debug("Received cancellation ack", decoded)
           mute_error = true
-        elseif decoded.error.code == protocol.ErrorCodes.ContentModified then
-          local _ = log.debug() and log.debug("Received content modified ack", decoded)
-          mute_error = true
         end
 
         if mute_error then

test/functional/fixtures/fake-lsp-server.lua

@@ -246,6 +246,35 @@ function tests.capabilities_for_client_supports_method()
   }
 end
 
+function tests.check_forward_request_cancelled()
+  skeleton {
+    on_init = function(_)
+      return { capabilities = {} }
+    end;
+    body = function()
+      expect_request("error_code_test", function()
+        return {code = -32800}, nil
+      end)
+      notify('finish')
+    end;
+  }
+end
+
+function tests.check_forward_content_modified()
+  skeleton {
+    on_init = function(_)
+      return { capabilities = {} }
+    end;
+    body = function()
+      expect_request("error_code_test", function()
+        return {code = -32801}, nil
+      end)
+      expect_notification('finish')
+      notify('finish')
+    end;
+  }
+end
+
 function tests.basic_finish()
   skeleton {
     on_init = function(params)

test/functional/plugin/lsp_spec.lua

@@ -480,6 +480,54 @@ describe('LSP', function()
       }
     end)
 
+    it('should not forward RequestCancelled to callback', function()
+      local expected_handlers = {
+        {NIL, "finish", {}, 1};
+      }
+      local client
+      test_rpc_server {
+        test_name = "check_forward_request_cancelled";
+        on_init = function(_client)
+          _client.request("error_code_test")
+          client = _client
+        end;
+        on_exit = function(code, signal)
+          eq(0, code, "exit code", fake_lsp_logfile)
+          eq(0, signal, "exit signal", fake_lsp_logfile)
+          eq(0, #expected_handlers, "did not call expected handler")
+        end;
+        on_handler = function(err, method, ...)
+          eq(table.remove(expected_handlers), {err, method, ...}, "expected handler")
+          if method == 'finish' then client.stop() end
+        end;
+      }
+    end)
+
+    it('should forward ContentModified to callback', function()
+      local expected_handlers = {
+        {NIL, "finish", {}, 1};
+        {{code = -32801}, "error_code_test", NIL, 1, NIL};
+      }
+      local client
+      test_rpc_server {
+        test_name = "check_forward_content_modified";
+        on_init = function(_client)
+          _client.request("error_code_test")
+          client = _client
+        end;
+        on_exit = function(code, signal)
+          eq(0, code, "exit code", fake_lsp_logfile)
+          eq(0, signal, "exit signal", fake_lsp_logfile)
+          eq(0, #expected_handlers, "did not call expected handler")
+        end;
+        on_handler = function(err, method, ...)
+          eq(table.remove(expected_handlers), {err, method, ...}, "expected handler")
+          if method == 'error_code_test' then client.notify("finish") end
+          if method == 'finish' then client.stop() end
+        end;
+      }
+    end)
+
     it('should not send didOpen if the buffer closes before init', function()
       local expected_handlers = {
         {NIL, {}, {method="shutdown", client_id=1}};