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86ab2b60cd
Opting-out of `Sized` with `?Sized` is now equivalent to adding a `MetaSized` bound, and adding a `MetaSized` or `PointeeSized` bound is equivalent to removing the default `Sized` bound - this commit implements this change in `rustc_hir_analysis::hir_ty_lowering`. `MetaSized` is also added as a supertrait of all traits, as this is necessary to preserve backwards compatibility. Unfortunately, non-global where clauses being preferred over item bounds (where `PointeeSized` bounds would be proven) - which can result in errors when a `PointeeSized` supertrait/bound/predicate is added to some items. Rather than `PointeeSized` being a bound on everything, it can be the absence of a bound on everything, as `?Sized` was.
29 lines
660 B
Rust
29 lines
660 B
Rust
//@ check-pass
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#![feature(sized_hierarchy)]
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// This is a reduction of some code in `library/core/src/cmp.rs` that would ICE if a default
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// `Pointee` bound is added - motivating the current status quo of `PointeeSized` being syntactic
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// sugar for an absense of any bounds whatsoever.
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use std::marker::PhantomData;
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pub trait Bar<'a> {
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type Foo;
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}
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pub struct Foo<'a, T: Bar<'a>> {
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phantom: PhantomData<&'a T>,
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}
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impl<'a, 'b, T> PartialEq<Foo<'b, T>> for Foo<'a, T>
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where
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T: for<'c> Bar<'c>,
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<T as Bar<'a>>::Foo: PartialEq<<T as Bar<'b>>::Foo>,
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{
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fn eq(&self, _: &Foo<'b, T>) -> bool {
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loop {}
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}
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}
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fn main() { }
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