trait Unsigned {
    const MAX: u8;
}

struct U8(u8);
impl Unsigned for U8 {
    const MAX: u8 = 0xff;
}

struct Sum<A,B>(A,B);

impl<A: Unsigned, B: Unsigned> Unsigned for Sum<A,B> {
    const MAX: u8 = A::MAX + B::MAX; //~ ERROR any use of this value will cause an error
}

fn foo<T>(_: T) -> &'static u8 {
    &Sum::<U8,U8>::MAX //~ ERROR E0080
}

fn main() {
    foo(0);
}