Default type parameters are handled improperly when calling methods

[Tobba]

pub trait Foo {
    type A;
}

pub trait Bar: Foo {
    fn foo<A, B=<Self as Foo>::A>(&self, a: A, b: B) { }
}

struct Baz;

impl Foo for Baz {
    type A = u32;
}

impl Bar for Baz { }

fn main() {
    let baz = Baz;
    Bar::foo::<u32>(&baz, 0, 0); // This works
    baz.foo::<u32>(0); // error: incorrect number of type parameters given for this method
}

[steveklabnik]

Triage: still relevant today

[jonas-schievink]

This now fails to compile with "defaults for type parameters are only allowed in struct, enum, type, or trait definitions". We might want to close this just like #26633.