29 lines
713 B
Rust
29 lines
713 B
Rust
//@ check-pass
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#![feature(coerce_unsized)]
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// Ensure that unsizing structs that contain ZSTs at non-zero offsets don't ICE
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use std::ops::CoerceUnsized;
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#[repr(C)]
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pub struct BoxWithZstTail<T: ?Sized>(Box<T>, ());
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impl<S: ?Sized, T: ?Sized> CoerceUnsized<BoxWithZstTail<T>> for BoxWithZstTail<S> where
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Box<S>: CoerceUnsized<Box<T>>
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{
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}
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pub fn noop_dyn_upcast_with_zst_tail(
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b: BoxWithZstTail<dyn ToString + Send>,
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) -> BoxWithZstTail<dyn ToString> {
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b
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}
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fn main() {
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let original = "foo";
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let boxed = BoxWithZstTail(Box::new(original) as Box<dyn ToString + Send>, ());
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let noop_upcasted = noop_dyn_upcast_with_zst_tail(boxed);
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assert_eq!(original, noop_upcasted.0.to_string());
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}
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