Redundant trait bounds

From time to time I find redundancies in my code as the result of moving trait bounds around while refactoring.

While true redundancy detection (with indirection) is probably out of scope …

trait Baz {}
trait Bar: Baz {}

trait Foo<T>
    where T: Bar {
    fn foo() where T: Baz;
}

… trivial cases like this should be totally doable:

trait Bar {}

trait Foo<T>
    where T: Bar {
    fn foo() where T: Bar;
}

Start with the two Rust examples in the issue and trace how rust-clippy implements lint checks for trait bounds. Determine how the repeated bound should be identified without attempting indirect redundancy detection. Done means the trivial redundant-bound case is reported while the indirect case remains out of scope; the payload names no files or tests.