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Rollup merge of #132065 - tifv:dangling-docs, r=Noratrieb

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Clarify documentation of `ptr::dangling()` function

Also fixes the safety comment in `NonNull::dangling()` function.

Fixes #132004.
This commit is contained in:
León Orell Valerian Liehr 2024-10-23 22:11:06 +02:00 committed by GitHub
commit b0a8e4e030
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2 changed files with 3 additions and 5 deletions
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4
library/core/src/ptr/mod.rs
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@ -602,7 +602,7 @@ pub const fn without_provenance<T>(addr: usize) -> *const T {
unsafe { mem::transmute(addr) }
}
/// Creates a new pointer that is dangling, but well-aligned.
/// Creates a new pointer that is dangling, but non-null and well-aligned.
///
/// This is useful for initializing types which lazily allocate, like
/// `Vec::new` does.
@ -645,7 +645,7 @@ pub const fn without_provenance_mut<T>(addr: usize) -> *mut T {
unsafe { mem::transmute(addr) }
}
/// Creates a new pointer that is dangling, but well-aligned.
/// Creates a new pointer that is dangling, but non-null and well-aligned.
///
/// This is useful for initializing types which lazily allocate, like
/// `Vec::new` does.

4
library/core/src/ptr/non_null.rs
View File

@ -107,9 +107,7 @@ impl<T: Sized> NonNull<T> {
#[must_use]
#[inline]
pub const fn dangling() -> Self {
// SAFETY: mem::align_of() returns a non-zero usize which is then casted
// to a *mut T. Therefore, `ptr` is not null and the conditions for
// calling new_unchecked() are respected.
// SAFETY: ptr::dangling_mut() returns a non-null well-aligned pointer.
unsafe {
let ptr = crate::ptr::dangling_mut::<T>();
NonNull::new_unchecked(ptr)