trait Foo {}
trait Baz : Foo {}

struct A;
struct B;
struct C;

impl Foo for A {}
impl Foo for B {}
impl Foo for C {}

impl Baz for A {}
impl Baz for B {}

struct PlatformDependent<F: Foo>(F);

impl<F: Baz> PlatformDependent<F> {
    fn bar() {
        Self::baz();
    }
}

impl PlatformDependent<A> {
    fn baz() {}
}

impl PlatformDependent<B> {
    fn baz() {}
}

/* No implementation for Platform  C */