mirror of https://github.com/rust-lang/rust
91 lines
2.4 KiB
Rust
91 lines
2.4 KiB
Rust
//@ run-pass
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#![feature(arbitrary_self_types, unsize, coerce_unsized, dispatch_from_dyn)]
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#![feature(rustc_attrs)]
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use std::{
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cell::Cell,
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ops::{Deref, CoerceUnsized, DispatchFromDyn},
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marker::Unsize,
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};
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struct Ptr<T: ?Sized>(Box<T>);
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impl<T: ?Sized> Deref for Ptr<T> {
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type Target = T;
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fn deref(&self) -> &T {
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&*self.0
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}
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}
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impl<T: Unsize<U> + ?Sized, U: ?Sized> CoerceUnsized<Ptr<U>> for Ptr<T> {}
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impl<T: Unsize<U> + ?Sized, U: ?Sized> DispatchFromDyn<Ptr<U>> for Ptr<T> {}
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struct CellPtr<'a, T: ?Sized>(Cell<&'a T>);
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impl<'a, T: ?Sized> Deref for CellPtr<'a, T> {
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type Target = T;
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fn deref(&self) -> &T {
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self.0.get()
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}
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}
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impl<'a, T: Unsize<U> + ?Sized, U: ?Sized> CoerceUnsized<CellPtr<'a, U>> for CellPtr<'a, T> {}
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impl<'a, T: Unsize<U> + ?Sized, U: ?Sized> DispatchFromDyn<CellPtr<'a, U>> for CellPtr<'a, T> {}
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struct Wrapper<T: ?Sized>(T);
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impl<T: ?Sized> Deref for Wrapper<T> {
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type Target = T;
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fn deref(&self) -> &T {
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&self.0
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}
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}
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impl<T: CoerceUnsized<U>, U> CoerceUnsized<Wrapper<U>> for Wrapper<T> {}
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impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<Wrapper<U>> for Wrapper<T> {}
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trait Trait {
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// This method isn't object-safe yet. Unsized by-value `self` is object-safe (but not callable
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// without unsized_locals), but wrappers arond `Self` currently are not.
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// FIXME (mikeyhew) uncomment this when unsized rvalues object-safety is implemented
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// fn wrapper(self: Wrapper<Self>) -> i32;
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fn ptr_wrapper(self: Ptr<Wrapper<Self>>) -> i32;
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fn wrapper_ptr(self: Wrapper<Ptr<Self>>) -> i32;
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fn wrapper_ptr_wrapper(self: Wrapper<Ptr<Wrapper<Self>>>) -> i32;
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fn cell(self: CellPtr<Self>) -> i32;
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}
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impl Trait for i32 {
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fn ptr_wrapper(self: Ptr<Wrapper<Self>>) -> i32 {
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**self
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}
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fn wrapper_ptr(self: Wrapper<Ptr<Self>>) -> i32 {
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**self
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}
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fn wrapper_ptr_wrapper(self: Wrapper<Ptr<Wrapper<Self>>>) -> i32 {
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***self
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}
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fn cell(self: CellPtr<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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let pw = Ptr(Box::new(Wrapper(5))) as Ptr<Wrapper<dyn Trait>>;
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assert_eq!(pw.ptr_wrapper(), 5);
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let wp = Wrapper(Ptr(Box::new(6))) as Wrapper<Ptr<dyn Trait>>;
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assert_eq!(wp.wrapper_ptr(), 6);
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let wpw = Wrapper(Ptr(Box::new(Wrapper(7)))) as Wrapper<Ptr<Wrapper<dyn Trait>>>;
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assert_eq!(wpw.wrapper_ptr_wrapper(), 7);
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let c = CellPtr(Cell::new(&8)) as CellPtr<dyn Trait>;
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assert_eq!(c.cell(), 8);
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}
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