error: generated operation marker `FooBar` collides with method `foo_bar`
  --> tests/ui/marker_collision.rs:11:14
   |
11 |     async fn foo__bar(&self) -> Response;
   |              ^^^^^^^^

error: first method generating marker `FooBar`
 --> tests/ui/marker_collision.rs:8:14
  |
8 |     async fn foo_bar(&self) -> Response;
  |              ^^^^^^^