Rustdoc doesn't follow type aliases in Deref's Target

[letheed]

The Methods from Deref<Target=...> will not appear in the documentation if Deref's Target is a type alias.
This works:

pub struct MyVeryLong<AndComplicated<Type>>;
pub type Foo = MyVeryLong<AndComplicated<Type>>;

pub struct Bar;
impl Deref for Bar {
    type Target = MyVeryLong<AndComplicated<Type>>;
    fn deref(&self) -> &Foo { ... }
}

This doesn't:

pub struct MyVeryLong<AndComplicated<Type>>;
pub type Foo = MyVeryLong<AndComplicated<Type>>;

pub struct Bar;
impl Deref for Bar {
    type Target = Foo;
    fn deref(&self) -> &Foo { ... }
}

[Mark-Simulacrum]

This is still the case today. The example below, when navigating to Bar's documentation, does not show the method happy.

pub struct FooA;
pub type FooB = FooA;

impl FooA {
        pub fn happy(&self) {}
}

pub struct Bar;
impl std::ops::Deref for Bar {
    type Target = FooB;
    fn deref(&self) -> &FooB { unimplemented!() }
}

[steveklabnik]

Triage: no change