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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.
10 lines
270 B
Rust
10 lines
270 B
Rust
//@ check-pass
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//@ compile-flags: --crate-type=lib
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#![feature(trait_alias)]
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// Checks that `?Sized` in a trait alias doesn't trigger an ICE.
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use std::ops::{Index, IndexMut};
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pub trait SlicePrereq<T> = ?Sized + IndexMut<usize, Output = <[T] as Index<usize>>::Output>;
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