| // run-pass |
| #![allow(unused_variables)] |
| // Check that a trait is still object-safe (and usable) if it has |
| // generic methods so long as they require `Self : Sized`. |
| |
| |
| trait Counter { |
| fn tick(&mut self) -> u32; |
| fn with<F:FnOnce(u32)>(&self, f: F) where Self : Sized; |
| } |
| |
| struct CCounter { |
| c: u32 |
| } |
| |
| impl Counter for CCounter { |
| fn tick(&mut self) -> u32 { self.c += 1; self.c } |
| fn with<F:FnOnce(u32)>(&self, f: F) { f(self.c); } |
| } |
| |
| fn tick1<C:Counter>(c: &mut C) { |
| tick2(c); |
| c.with(|i| ()); |
| } |
| |
| 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 }; |
| tick1(&mut c); |
| assert_eq!(c.tick(), 3); |
| } |