src/test/ui/dst/dst-bad-assign-3.rs

   1 // Forbid assignment into a dynamically sized type.
   2
   3 #![feature(unsized_tuple_coercion)]
   4
   5 type Fat<T> = (isize, &'static str, T);
   6
   7 #[derive(PartialEq,Eq)]
   8 struct Bar;
   9
  10 #[derive(PartialEq,Eq)]
  11 struct Bar1 {
  12     f: isize
  13 }
  14
  15 trait ToBar {
  16     fn to_bar(&self) -> Bar;
  17     fn to_val(&self) -> isize;
  18 }
  19
  20 impl ToBar for Bar1 {
  21     fn to_bar(&self) -> Bar {
  22         Bar
  23     }
  24     fn to_val(&self) -> isize {
  25         self.f
  26     }
  27 }
  28
  29 pub fn main() {
  30     // Assignment.
  31     let f5: &mut Fat<dyn ToBar> = &mut (5, "some str", Bar1 {f :42});
  32     let z: Box<dyn ToBar> = Box::new(Bar1 {f: 36});
  33     f5.2 = Bar1 {f: 36};
  34     //~^ ERROR mismatched types
  35     //~| expected trait `ToBar`, found struct `Bar1`
  36     //~| expected trait object `dyn ToBar`
  37     //~| found struct `Bar1`
  38     //~| ERROR the size for values of type
  39 }