swift-protobuf/Protos/CompileTests/MultiModule/Sources/ModuleA/a.proto

enum E {
  E_UNSET = 0;
  E_A = 1;
  E_B = 2;
}

message A {
  optional E e = 1;
  extensions 100 to 1000;
}

extend A {
  optional string ext_str = 100;
}