// Forbid assignment into a dynamically sized type. #![feature(unsized_tuple_coercion)] type Fat = (isize, &'static str, T); #[derive(PartialEq,Eq)] struct Bar; #[derive(PartialEq,Eq)] struct Bar1 { f: isize } trait ToBar { fn to_bar(&self) -> Bar; fn to_val(&self) -> isize; } impl ToBar for Bar1 { fn to_bar(&self) -> Bar { Bar } fn to_val(&self) -> isize { self.f } } pub fn main() { // Assignment. let f5: &mut Fat = &mut (5, "some str", Bar1 {f :42}); let z: Box = Box::new(Bar1 {f: 36}); f5.2 = Bar1 {f: 36}; //~^ ERROR mismatched types //~| expected trait object `dyn ToBar`, found struct `Bar1` //~| expected trait object `dyn ToBar` //~| found struct `Bar1` //~| ERROR the size for values of type }