error[E0276]: impl has stricter requirements than trait
  --> $DIR/missing-where-clause-on-trait.rs:7:39
   |
LL |     type Assoc<'a, 'b>;
   |     ------------------ definition of `Assoc` from trait
...
LL |     type Assoc<'a, 'b> = () where 'a: 'b;
   |                                       ^^ impl has extra requirement `'a: 'b`
   |
help: remove the `where` clause
   |
LL -     type Assoc<'a, 'b> = () where 'a: 'b;
LL +     type Assoc<'a, 'b> = () ;
   |

error: aborting due to 1 previous error

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