mirror of https://github.com/rust-lang/rust.git
57 lines
1.3 KiB
Rust
57 lines
1.3 KiB
Rust
//@ check-pass
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//@ revisions: old next
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//@[next] compile-flags: -Znext-solver
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#![feature(ptr_metadata)]
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use std::ptr::{self, Pointee};
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fn cast_same_meta<T: ?Sized, U: ?Sized>(ptr: *const T) -> *const U
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where
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T: Pointee<Metadata = <U as Pointee>::Metadata>,
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{
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let (thin, meta) = ptr.to_raw_parts();
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ptr::from_raw_parts(thin, meta)
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}
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struct Wrapper<T: ?Sized>(T);
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// normalize `Wrapper<T>::Metadata` -> `T::Metadata`
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fn wrapper_to_tail<T: ?Sized>(ptr: *const T) -> *const Wrapper<T> {
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cast_same_meta(ptr)
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}
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// normalize `Wrapper<T>::Metadata` -> `T::Metadata` -> `()`
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fn wrapper_to_unit<T>(ptr: *const ()) -> *const Wrapper<T> {
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cast_same_meta(ptr)
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}
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trait Project {
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type Assoc: ?Sized;
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}
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struct WrapperProject<T: ?Sized + Project>(T::Assoc);
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// normalize `WrapperProject<T>::Metadata` -> `T::Assoc::Metadata`
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fn wrapper_project_tail<T: ?Sized + Project>(ptr: *const T::Assoc) -> *const WrapperProject<T> {
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cast_same_meta(ptr)
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}
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// normalize `WrapperProject<T>::Metadata` -> `T::Assoc::Metadata` -> `()`
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fn wrapper_project_unit<T: ?Sized + Project>(ptr: *const ()) -> *const WrapperProject<T>
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where
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T::Assoc: Sized,
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{
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cast_same_meta(ptr)
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}
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// normalize `<[T] as Pointee>::Metadata` -> `usize`, even if `[T]: Sized`
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fn sized_slice<T>(ptr: *const [T]) -> *const str
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where
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[T]: Sized,
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{
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cast_same_meta(ptr)
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}
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fn main() {}
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