mirror of https://github.com/rust-lang/rust
40 lines
736 B
Rust
40 lines
736 B
Rust
//@ run-pass
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// Check that a trait is still object-safe (and usable) if it has
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// methods that return `Self` so long as they require `Self : Sized`.
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trait Counter {
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fn new() -> Self where Self : Sized;
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fn tick(&mut self) -> u32;
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}
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struct CCounter {
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c: u32
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}
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impl Counter for CCounter {
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fn new() -> CCounter { CCounter { c: 0 } }
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fn tick(&mut self) -> u32 { self.c += 1; self.c }
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}
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fn preticked<C:Counter>() -> C {
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let mut c: C = Counter::new();
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tick(&mut c);
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c
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}
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fn tick(c: &mut dyn Counter) {
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tick_generic(c);
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}
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fn tick_generic<C:?Sized+Counter>(c: &mut C) {
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c.tick();
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c.tick();
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}
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fn main() {
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let mut c = preticked::<CCounter>();
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tick(&mut c);
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assert_eq!(c.tick(), 5);
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}
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