error[E0050]: method `bar` has 1 parameter but the declaration in trait `Foo::bar` has 2
  --> $DIR/impl-different-num-params.rs:5:12
   |
LL |     fn bar(&self, x: usize) -> Self;
   |            --------------- trait requires 2 parameters
...
LL |     fn bar(&self) -> isize {
   |            ^^^^^ expected 2 parameters, found 1

error: aborting due to 1 previous error

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