// build-fail trait Foo { const AMT: usize; } enum Bar { First(A), Second(B), } impl Foo for Bar { const AMT: usize = [A::AMT][(A::AMT > B::AMT) as usize]; //~ERROR evaluation of ` as Foo>::AMT` failed } impl Foo for u8 { const AMT: usize = 1; } impl Foo for u16 { const AMT: usize = 2; } fn main() { println!("{}", as Foo>::AMT); //~^ ERROR evaluation of constant value failed //~| ERROR erroneous constant used }