error: expected type, found service definition `buf.test.S`
  --> testdata/services/references.proto:6:14
   |
 6 |     optional S s = 1;
   |              ^ expected type
 7 |     optional S.X x = 2;
...
10 | service S {
   |         - defined here

error: cannot find `S.X` in this scope
  --> testdata/services/references.proto:7:14
   |
 7 |     optional S.X x = 2;
   |              ^^^ not found in this scope
   |
   = help: the full name of this scope is `buf.test.M`

error: expected message type, found service method `buf.test.S2.M`
  --> testdata/services/references.proto:17:11
   |
17 |     rpc M(M) returns (buf.test.M);
   |         - ^ expected message type
   |         |
   |         defined here

encountered 3 errors