error[E0050]: method `foo` has 2 parameters but the declaration in trait `Foo::foo` has 3
  --> $DIR/trait-method-number-parameters.rs:7:9
   |
LL |       fn foo(&mut self, x: i32, y: i32) -> i32;
   |              ------------------------- trait requires 3 parameters
...
LL | /         &mut self,
LL | |         x: i32,
   | |______________^ expected 3 parameters, found 2

error: aborting due to previous error

For more information about this error, try `rustc --explain E0050`.
