f12c250e40
Rename `CoerceSized` to `DispatchFromDyn`, and reverse the direction so that, for example, you write
```
impl<T: Unsize<U>, U> DispatchFromDyn<*const U> for *const T {}
```
instead of
```
impl<T: Unsize<U>, U> DispatchFromDyn<*const T> for *const U {}
```
this way the trait is really just a subset of `CoerceUnsized`.
The checks in object_safety.rs are updated for the new trait, and some documentation and method names in there are updated for the new trait name — e.g. `receiver_is_coercible` is now called `receiver_is_dispatchable`. Since the trait now works in the opposite direction, some code had to updated here for that too.
I did not update the error messages for invalid `CoerceSized` (now `DispatchFromDyn`) implementations, except to find/replace `CoerceSized` with `DispatchFromDyn`. Will ask for suggestions in the PR thread.
44 lines
1.1 KiB
Rust
44 lines
1.1 KiB
Rust
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![feature(unsize, dispatch_from_dyn)]
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use std::{
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ops::DispatchFromDyn,
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marker::{Unsize, PhantomData},
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};
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struct WrapperWithExtraField<T>(T, i32);
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impl<T, U> DispatchFromDyn<WrapperWithExtraField<U>> for WrapperWithExtraField<T>
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where
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T: DispatchFromDyn<U>,
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{} //~^^^ ERROR [E0378]
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struct MultiplePointers<T: ?Sized>{
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ptr1: *const T,
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ptr2: *const T,
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}
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impl<T: ?Sized, U: ?Sized> DispatchFromDyn<MultiplePointers<U>> for MultiplePointers<T>
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where
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T: Unsize<U>,
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{} //~^^^ ERROR [E0378]
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struct NothingToCoerce<T: ?Sized> {
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data: PhantomData<T>,
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}
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impl<T: ?Sized, U: ?Sized> DispatchFromDyn<NothingToCoerce<T>> for NothingToCoerce<U> {}
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//~^ ERROR [E0378]
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fn main() {}
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