884d0e031a
As core uses an extern type (`ptr::VTable`), the default `?Sized` to `MetaSized` migration isn't sufficient, and some code that previously accepted `VTable` needs relaxed to continue to accept extern types. Similarly, the compiler uses many extern types in `rustc_codegen_llvm` and in the `rustc_middle::ty::List` implementation (`OpaqueListContents`) some bounds must be relaxed to continue to accept these types. Unfortunately, due to the current inability to relax `Deref::Target`, some of the bounds in the standard library are forced to be stricter than they ideally would be.
34 lines
904 B
Rust
34 lines
904 B
Rust
use std::ptr::Alignment;
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use rustc_serialize::PointeeSized;
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/// Returns the ABI-required minimum alignment of a type in bytes.
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///
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/// This is equivalent to [`align_of`], but also works for some unsized
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/// types (e.g. slices or rustc's `List`s).
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pub const fn align_of<T: ?Sized + Aligned>() -> Alignment {
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T::ALIGN
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}
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/// A type with a statically known alignment.
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///
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/// # Safety
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///
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/// `Self::ALIGN` must be equal to the alignment of `Self`. For sized types it
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/// is [`align_of::<Self>()`], for unsized types it depends on the type, for
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/// example `[T]` has alignment of `T`.
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///
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/// [`align_of::<Self>()`]: align_of
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pub unsafe trait Aligned: PointeeSized {
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/// Alignment of `Self`.
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const ALIGN: Alignment;
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}
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unsafe impl<T> Aligned for T {
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const ALIGN: Alignment = Alignment::of::<Self>();
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}
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unsafe impl<T> Aligned for [T] {
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const ALIGN: Alignment = Alignment::of::<T>();
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}
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