error[E0276]: impl has stricter requirements than trait
  --> $DIR/missing-where-clause-on-trait.rs:9:39
   |
LL |     type Assoc<'a, 'b>;
   |     ------------------ definition of `Assoc` from trait
...
LL |     type Assoc<'a, 'b> = () where 'a: 'b;
   |                                       ^^ impl has extra requirement `'a: 'b`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0276`.