error[E0277]: the trait bound `Bar: Foo<usize>` is not satisfied
  --> $DIR/issue-21659-show-relevant-trait-impls-1.rs:24:12
   |
LL |     f1.foo(1usize);
   |        --- ^^^^^^ the trait `Foo<usize>` is not implemented for `Bar`
   |        |
   |        required by a bound introduced by this call
   |
   = help: the following other types implement trait `Foo<A>`:
             `Bar` implements `Foo<i32>`
             `Bar` implements `Foo<u8>`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0277`.