mirror of https://github.com/rust-lang/rust
44 lines
788 B
Rust
44 lines
788 B
Rust
//@ run-pass
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// Test a very simple custom DST coercion.
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#![feature(unsize, coerce_unsized)]
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use std::ops::CoerceUnsized;
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use std::marker::Unsize;
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struct Bar<T: ?Sized> {
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x: *const T,
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}
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impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<Bar<U>> for Bar<T> {}
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trait Baz {
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fn get(&self) -> i32;
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}
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impl Baz for i32 {
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fn get(&self) -> i32 {
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*self
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}
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}
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fn main() {
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// Arrays.
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let a: Bar<[i32; 3]> = Bar { x: &[1, 2, 3] };
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// This is the actual coercion.
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let b: Bar<[i32]> = a;
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unsafe {
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assert_eq!((*b.x)[0], 1);
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assert_eq!((*b.x)[1], 2);
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assert_eq!((*b.x)[2], 3);
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}
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// Trait objects.
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let a: Bar<i32> = Bar { x: &42 };
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let b: Bar<dyn Baz> = a;
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unsafe {
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assert_eq!((*b.x).get(), 42);
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}
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}
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