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Implemented const casts of raw pointers

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This adds `as_mut()` method for `*const T` and `as_const()` for `*mut T`
which are intended to make casting of consts safer. This was discussed
in the [internals discussion][discussion].

[discussion]: https://internals.rust-lang.org/t/casting-constness-can-be-risky-heres-a-simple-fix/15933
This commit is contained in:
Martin Habovstiak 2022-01-08 00:03:02 +01:00
parent e012a191d7
commit 1a96623513
2 changed files with 24 additions and 0 deletions
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10
library/core/src/ptr/const_ptr.rs
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@ -48,6 +48,16 @@ impl<T: ?Sized> *const T {
self as _
}
/// Changes constness without changing the type.
///
/// This is a bit safer than `as` because it wouldn't silently change the type if the code is
/// refactored.
#[unstable(feature = "ptr_const_cast", issue = "92675")]
#[rustc_const_unstable(feature = "ptr_const_cast", issue = "92675")]
pub const fn as_mut(self) -> *mut T {
self as _
}
/// Casts a pointer to its raw bits.
///
/// This is equivalent to `as usize`, but is more specific to enhance readability.