135 lines
3.5 KiB
Rust
135 lines
3.5 KiB
Rust
#![feature(arbitrary_self_types, unsize, coerce_unsized, dispatch_from_dyn)]
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#![feature(rustc_attrs)]
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fn pin_box_dyn() {
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use std::pin::Pin;
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trait Foo {
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fn bar(self: Pin<&mut Self>) -> bool;
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}
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impl Foo for &'static str {
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fn bar(self: Pin<&mut Self>) -> bool {
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true
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}
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}
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let mut test: Pin<Box<dyn Foo>> = Box::pin("foo");
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test.as_mut().bar();
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}
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fn stdlib_pointers() {
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use std::{
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rc::Rc,
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sync::Arc,
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pin::Pin,
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};
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trait Trait {
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fn by_rc(self: Rc<Self>) -> i64;
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fn by_arc(self: Arc<Self>) -> i64;
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fn by_pin_mut(self: Pin<&mut Self>) -> i64;
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fn by_pin_box(self: Pin<Box<Self>>) -> i64;
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}
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impl Trait for i64 {
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fn by_rc(self: Rc<Self>) -> i64 {
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*self
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}
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fn by_arc(self: Arc<Self>) -> i64 {
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*self
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}
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fn by_pin_mut(self: Pin<&mut Self>) -> i64 {
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*self
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}
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fn by_pin_box(self: Pin<Box<Self>>) -> i64 {
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*self
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}
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}
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let rc = Rc::new(1i64) as Rc<dyn Trait>;
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assert_eq!(1, rc.by_rc());
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let arc = Arc::new(2i64) as Arc<dyn Trait>;
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assert_eq!(2, arc.by_arc());
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let mut value = 3i64;
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let pin_mut = Pin::new(&mut value) as Pin<&mut dyn Trait>;
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assert_eq!(3, pin_mut.by_pin_mut());
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let pin_box = Into::<Pin<Box<i64>>>::into(Box::new(4i64)) as Pin<Box<dyn Trait>>;
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assert_eq!(4, pin_box.by_pin_box());
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}
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fn pointers_and_wrappers() {
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use std::{
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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 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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}
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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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}
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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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}
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fn main() {
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pin_box_dyn();
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stdlib_pointers();
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pointers_and_wrappers();
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}
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