rust/tests/ui/sized-hierarchy/trait-aliases.rs
David Wood 86ab2b60cd
hir_analysis: add {Meta,Pointee}Sized bounds
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.
2025-06-16 23:04:33 +00:00

10 lines
270 B
Rust

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