| // run-pass |
| #![allow(unused_mut)] |
| // Check that a trait is still object-safe (and usable) if it has |
| // methods with by-value self so long as they require `Self : Sized`. |
| |
| |
| trait Counter { |
| fn tick(&mut self) -> u32; |
| fn get(self) -> u32 where Self : Sized; |
| } |
| |
| struct CCounter { |
| c: u32 |
| } |
| |
| impl Counter for CCounter { |
| fn tick(&mut self) -> u32 { self.c += 1; self.c } |
| fn get(self) -> u32 where Self : Sized { self.c } |
| } |
| |
| fn tick1<C:Counter>(mut c: C) -> u32 { |
| tick2(&mut c); |
| c.get() |
| } |
| |
| fn tick2(c: &mut dyn Counter) { |
| tick3(c); |
| } |
| |
| fn tick3<C:?Sized+Counter>(c: &mut C) { |
| c.tick(); |
| c.tick(); |
| } |
| |
| fn main() { |
| let mut c = CCounter { c: 0 }; |
| let value = tick1(c); |
| assert_eq!(value, 2); |
| } |