error[E0277]: the trait bound `dyn Foo<(isize,), isize, Output=()>: Eq<dyn Foo<(isize,), Output=()>>` is not satisfied
  --> $DIR/unboxed-closure-sugar-default.rs:31:5
   |
LL |     eq::< Foo<(isize,),isize,Output=()>,      Foo(isize)                      >();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Eq<dyn Foo<(isize,), Output=()>>` is not implemented for `dyn Foo<(isize,), isize, Output=()>`
   |
note: required by `eq`
  --> $DIR/unboxed-closure-sugar-default.rs:24:1
   |
LL | fn eq<A: ?Sized,B: ?Sized>() where A : Eq<B> { }
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

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