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49 lines
1011 B
Rust
49 lines
1011 B
Rust
//@ run-pass
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#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
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trait Foo: std::fmt::Debug + Eq {}
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impl<T: std::fmt::Debug + Eq> Foo for T {}
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fn hide<T: Foo>(x: T) -> impl Foo {
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x
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}
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trait Leak<T>: Sized {
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fn leak(self) -> T;
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}
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impl<T, U> Leak<T> for U {
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default fn leak(self) -> T { panic!("type mismatch") }
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}
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impl<T> Leak<T> for T {
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fn leak(self) -> T { self }
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}
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trait CheckIfSend: Sized {
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type T: Default;
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fn check(self) -> Self::T { Default::default() }
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}
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impl<T> CheckIfSend for T {
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default type T = ();
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}
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impl<T: Send> CheckIfSend for T {
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type T = bool;
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}
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fn lucky_seven() -> impl Fn(usize) -> u8 {
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let a = [1, 2, 3, 4, 5, 6, 7];
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move |i| a[i]
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}
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fn main() {
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assert_eq!(hide(42), hide(42));
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assert_eq!(std::mem::size_of_val(&hide([0_u8; 5])), 5);
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assert_eq!(std::mem::size_of_val(&lucky_seven()), 7);
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assert_eq!(Leak::<i32>::leak(hide(5_i32)), 5_i32);
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assert_eq!(CheckIfSend::check(hide(0_i32)), false);
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}
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