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// Check that trait-objects without a principal codegen properly. | ||
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use std::sync::atomic::{AtomicUsize, Ordering}; | ||
use std::mem; | ||
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// Array is to make sure the size is not exactly pointer-size, so | ||
// we can be sure we are measuring the right size in the | ||
// `size_of_val` test. | ||
struct SetOnDrop<'a>(&'a AtomicUsize, [u8; 64]); | ||
impl<'a> Drop for SetOnDrop<'a> { | ||
fn drop(&mut self) { | ||
self.0.store(self.0.load(Ordering::Relaxed)+1, Ordering::Relaxed); | ||
} | ||
} | ||
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trait TypeEq<V: ?Sized> {} | ||
impl<T: ?Sized> TypeEq<T> for T {} | ||
fn assert_types_eq<U: ?Sized, V: ?Sized>() where U: TypeEq<V> {} | ||
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fn main() { | ||
// Check that different ways of writing the same type are equal. | ||
assert_types_eq::<dyn Sync, dyn Sync + Sync>(); | ||
assert_types_eq::<dyn Sync + Send, dyn Send + Sync>(); | ||
assert_types_eq::<dyn Sync + Send + Sync, dyn Send + Sync>(); | ||
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// Check that codegen works. | ||
// | ||
// Using `AtomicUsize` here because `Cell<u32>` is not `Sync`, and | ||
// so can't be made into a `Box<dyn Sync>`. | ||
let c = AtomicUsize::new(0); | ||
{ | ||
let d: Box<dyn Sync> = Box::new(SetOnDrop(&c, [0; 64])); | ||
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assert_eq!(mem::size_of_val(&*d), | ||
mem::size_of::<SetOnDrop>()); | ||
assert_eq!(mem::align_of_val(&*d), | ||
mem::align_of::<SetOnDrop>()); | ||
assert_eq!(c.load(Ordering::Relaxed), 0); | ||
} | ||
assert_eq!(c.load(Ordering::Relaxed), 1); | ||
} |