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stabilize const_ptr_is_null
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RalfJung committed Nov 16, 2024

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1 parent 46e8d20 commit 65d158c
Showing 4 changed files with 9 additions and 8 deletions.
1 change: 0 additions & 1 deletion library/core/src/lib.rs
Original file line number Diff line number Diff line change
@@ -121,7 +121,6 @@
#![feature(const_heap)]
#![feature(const_nonnull_new)]
#![feature(const_pin_2)]
#![feature(const_ptr_is_null)]
#![feature(const_ptr_sub_ptr)]
#![feature(const_raw_ptr_comparison)]
#![feature(const_size_of_val)]
8 changes: 5 additions & 3 deletions library/core/src/ptr/const_ptr.rs
Original file line number Diff line number Diff line change
@@ -29,16 +29,18 @@ impl<T: ?Sized> *const T {
/// assert!(!ptr.is_null());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
#[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")]
#[rustc_diagnostic_item = "ptr_const_is_null"]
#[inline]
#[rustc_allow_const_fn_unstable(const_eval_select)]
pub const fn is_null(self) -> bool {
// Compare via a cast to a thin pointer, so fat pointers are only
// considering their "data" part for null-ness.
let ptr = self as *const u8;
const_eval_select!(
@capture { ptr: *const u8 } -> bool:
if const #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] {
// This use of `const_raw_ptr_comparison` has been explicitly blessed by t-lang.
if const #[rustc_allow_const_fn_unstable(const_raw_ptr_comparison)] {
match (ptr).guaranteed_eq(null_mut()) {
Some(res) => res,
// To remain maximally convervative, we stop execution when we don't
@@ -280,7 +282,7 @@ impl<T: ?Sized> *const T {
/// }
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
#[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")]
#[inline]
pub const unsafe fn as_ref<'a>(self) -> Option<&'a T> {
// SAFETY: the caller must guarantee that `self` is valid
6 changes: 3 additions & 3 deletions library/core/src/ptr/mut_ptr.rs
Original file line number Diff line number Diff line change
@@ -29,7 +29,7 @@ impl<T: ?Sized> *mut T {
/// assert!(!ptr.is_null());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
#[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")]
#[rustc_diagnostic_item = "ptr_is_null"]
#[inline]
pub const fn is_null(self) -> bool {
@@ -271,7 +271,7 @@ impl<T: ?Sized> *mut T {
/// }
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
#[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")]
#[inline]
pub const unsafe fn as_ref<'a>(self) -> Option<&'a T> {
// SAFETY: the caller must guarantee that `self` is valid for a
@@ -619,7 +619,7 @@ impl<T: ?Sized> *mut T {
/// println!("{s:?}"); // It'll print: "[4, 2, 3]".
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
#[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")]
#[inline]
pub const unsafe fn as_mut<'a>(self) -> Option<&'a mut T> {
// SAFETY: the caller must guarantee that `self` is be valid for
2 changes: 1 addition & 1 deletion library/core/src/ub_checks.rs
Original file line number Diff line number Diff line change
@@ -65,7 +65,7 @@ macro_rules! assert_unsafe_precondition {
#[inline]
#[rustc_nounwind]
#[cfg_attr(bootstrap, rustc_const_unstable(feature = "const_ub_checks", issue = "none"))]
#[rustc_allow_const_fn_unstable(const_ptr_is_null, const_ub_checks)] // only for UB checks
#[rustc_allow_const_fn_unstable(const_ub_checks)] // only for UB checks
const fn precondition_check($($name:$ty),*) {
if !$e {
::core::panicking::panic_nounwind(

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