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make ptr metadata functions callable from stable const fn #130966

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Oct 1, 2024
Merged

make ptr metadata functions callable from stable const fn #130966

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5c3ceb3
make ptr metadata functions callable from stable const fn
RalfJung Sep 28, 2024
7650307
add test ensuring we cannot call const-stable unstable functions
RalfJung Sep 30, 2024
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4 changes: 2 additions & 2 deletions library/core/src/intrinsics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3160,7 +3160,7 @@ pub const fn type_id<T: ?Sized + 'static>() -> u128 {
/// change the possible layouts of pointers.
#[rustc_nounwind]
#[unstable(feature = "core_intrinsics", issue = "none")]
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
#[rustc_intrinsic]
#[rustc_intrinsic_must_be_overridden]
pub const fn aggregate_raw_ptr<P: AggregateRawPtr<D, Metadata = M>, D, M>(_data: D, _meta: M) -> P {
Expand All @@ -3185,7 +3185,7 @@ impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*mut T> for *mut P {
/// This is used to implement functions like `ptr::metadata`.
#[rustc_nounwind]
#[unstable(feature = "core_intrinsics", issue = "none")]
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
#[rustc_intrinsic]
#[rustc_intrinsic_must_be_overridden]
pub const fn ptr_metadata<P: ptr::Pointee<Metadata = M> + ?Sized, M>(_ptr: *const P) -> M {
Expand Down
10 changes: 1 addition & 9 deletions library/core/src/ptr/const_ptr.rs
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Expand Up @@ -92,7 +92,7 @@ impl<T: ?Sized> *const T {
/// }
/// ```
#[unstable(feature = "set_ptr_value", issue = "75091")]
#[rustc_const_unstable(feature = "set_ptr_value", issue = "75091")]
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
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Hmm, seems odd to mark this as const-stable when it's not normal-stable? I don't remember use doing that elsewhere?

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There is precedent for that: the raw_vec_internals_const feature.

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Another example: #128228 (comment). tbh it also feels surprising to me 😅

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Yeah I think we should redo how we do const stability. See #129815.

But for now this is the system that we got.

#[must_use = "returns a new pointer rather than modifying its argument"]
#[inline]
pub const fn with_metadata_of<U>(self, meta: *const U) -> *const U
Expand Down Expand Up @@ -412,7 +412,6 @@ impl<T: ?Sized> *const T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
pub const unsafe fn byte_offset(self, count: isize) -> Self {
// SAFETY: the caller must uphold the safety contract for `offset`.
Expand Down Expand Up @@ -495,7 +494,6 @@ impl<T: ?Sized> *const T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
pub const fn wrapping_byte_offset(self, count: isize) -> Self {
self.cast::<u8>().wrapping_offset(count).with_metadata_of(self)
}
Expand Down Expand Up @@ -645,7 +643,6 @@ impl<T: ?Sized> *const T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
pub const unsafe fn byte_offset_from<U: ?Sized>(self, origin: *const U) -> isize {
// SAFETY: the caller must uphold the safety contract for `offset_from`.
Expand Down Expand Up @@ -873,7 +870,6 @@ impl<T: ?Sized> *const T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
pub const unsafe fn byte_add(self, count: usize) -> Self {
// SAFETY: the caller must uphold the safety contract for `add`.
Expand Down Expand Up @@ -956,7 +952,6 @@ impl<T: ?Sized> *const T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
pub const unsafe fn byte_sub(self, count: usize) -> Self {
// SAFETY: the caller must uphold the safety contract for `sub`.
Expand Down Expand Up @@ -1039,7 +1034,6 @@ impl<T: ?Sized> *const T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
pub const fn wrapping_byte_add(self, count: usize) -> Self {
self.cast::<u8>().wrapping_add(count).with_metadata_of(self)
}
Expand Down Expand Up @@ -1120,7 +1114,6 @@ impl<T: ?Sized> *const T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
pub const fn wrapping_byte_sub(self, count: usize) -> Self {
self.cast::<u8>().wrapping_sub(count).with_metadata_of(self)
}
Expand Down Expand Up @@ -1554,7 +1547,6 @@ impl<T> *const [T] {
#[inline]
#[stable(feature = "slice_ptr_len", since = "1.79.0")]
#[rustc_const_stable(feature = "const_slice_ptr_len", since = "1.79.0")]
#[rustc_allow_const_fn_unstable(ptr_metadata)]
pub const fn len(self) -> usize {
metadata(self)
}
Expand Down
6 changes: 3 additions & 3 deletions library/core/src/ptr/metadata.rs
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Expand Up @@ -92,7 +92,7 @@ pub trait Thin = Pointee<Metadata = ()>;
///
/// assert_eq!(std::ptr::metadata("foo"), 3_usize);
/// ```
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
#[inline]
pub const fn metadata<T: ?Sized>(ptr: *const T) -> <T as Pointee>::Metadata {
ptr_metadata(ptr)
Expand All @@ -106,7 +106,7 @@ pub const fn metadata<T: ?Sized>(ptr: *const T) -> <T as Pointee>::Metadata {
///
/// [`slice::from_raw_parts`]: crate::slice::from_raw_parts
#[unstable(feature = "ptr_metadata", issue = "81513")]
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
#[inline]
pub const fn from_raw_parts<T: ?Sized>(
data_pointer: *const impl Thin,
Expand All @@ -120,7 +120,7 @@ pub const fn from_raw_parts<T: ?Sized>(
///
/// See the documentation of [`from_raw_parts`] for more details.
#[unstable(feature = "ptr_metadata", issue = "81513")]
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
#[inline]
pub const fn from_raw_parts_mut<T: ?Sized>(
data_pointer: *mut impl Thin,
Expand Down
3 changes: 0 additions & 3 deletions library/core/src/ptr/mod.rs
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Expand Up @@ -599,7 +599,6 @@ pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_promotable]
#[rustc_const_stable(feature = "const_ptr_null", since = "1.24.0")]
#[rustc_allow_const_fn_unstable(ptr_metadata)]
#[rustc_diagnostic_item = "ptr_null"]
pub const fn null<T: ?Sized + Thin>() -> *const T {
from_raw_parts(without_provenance::<()>(0), ())
Expand All @@ -625,7 +624,6 @@ pub const fn null<T: ?Sized + Thin>() -> *const T {
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_promotable]
#[rustc_const_stable(feature = "const_ptr_null", since = "1.24.0")]
#[rustc_allow_const_fn_unstable(ptr_metadata)]
#[rustc_diagnostic_item = "ptr_null_mut"]
pub const fn null_mut<T: ?Sized + Thin>() -> *mut T {
from_raw_parts_mut(without_provenance_mut::<()>(0), ())
Expand Down Expand Up @@ -949,7 +947,6 @@ pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T {
#[inline]
#[stable(feature = "slice_from_raw_parts", since = "1.42.0")]
#[rustc_const_stable(feature = "const_slice_from_raw_parts", since = "1.64.0")]
#[rustc_allow_const_fn_unstable(ptr_metadata)]
#[rustc_diagnostic_item = "ptr_slice_from_raw_parts"]
pub const fn slice_from_raw_parts<T>(data: *const T, len: usize) -> *const [T] {
from_raw_parts(data, len)
Expand Down
10 changes: 1 addition & 9 deletions library/core/src/ptr/mut_ptr.rs
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Expand Up @@ -74,7 +74,7 @@ impl<T: ?Sized> *mut T {
/// }
/// ```
#[unstable(feature = "set_ptr_value", issue = "75091")]
#[rustc_const_unstable(feature = "set_ptr_value", issue = "75091")]
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
#[must_use = "returns a new pointer rather than modifying its argument"]
#[inline]
pub const fn with_metadata_of<U>(self, meta: *const U) -> *mut U
Expand Down Expand Up @@ -412,7 +412,6 @@ impl<T: ?Sized> *mut T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
pub const unsafe fn byte_offset(self, count: isize) -> Self {
// SAFETY: the caller must uphold the safety contract for `offset`.
Expand Down Expand Up @@ -492,7 +491,6 @@ impl<T: ?Sized> *mut T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
pub const fn wrapping_byte_offset(self, count: isize) -> Self {
self.cast::<u8>().wrapping_offset(count).with_metadata_of(self)
}
Expand Down Expand Up @@ -808,7 +806,6 @@ impl<T: ?Sized> *mut T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
pub const unsafe fn byte_offset_from<U: ?Sized>(self, origin: *const U) -> isize {
// SAFETY: the caller must uphold the safety contract for `offset_from`.
Expand Down Expand Up @@ -954,7 +951,6 @@ impl<T: ?Sized> *mut T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
pub const unsafe fn byte_add(self, count: usize) -> Self {
// SAFETY: the caller must uphold the safety contract for `add`.
Expand Down Expand Up @@ -1037,7 +1033,6 @@ impl<T: ?Sized> *mut T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
pub const unsafe fn byte_sub(self, count: usize) -> Self {
// SAFETY: the caller must uphold the safety contract for `sub`.
Expand Down Expand Up @@ -1118,7 +1113,6 @@ impl<T: ?Sized> *mut T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
pub const fn wrapping_byte_add(self, count: usize) -> Self {
self.cast::<u8>().wrapping_add(count).with_metadata_of(self)
}
Expand Down Expand Up @@ -1197,7 +1191,6 @@ impl<T: ?Sized> *mut T {
#[inline(always)]
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
#[rustc_allow_const_fn_unstable(set_ptr_value)]
pub const fn wrapping_byte_sub(self, count: usize) -> Self {
self.cast::<u8>().wrapping_sub(count).with_metadata_of(self)
}
Expand Down Expand Up @@ -1804,7 +1797,6 @@ impl<T> *mut [T] {
#[inline(always)]
#[stable(feature = "slice_ptr_len", since = "1.79.0")]
#[rustc_const_stable(feature = "const_slice_ptr_len", since = "1.79.0")]
#[rustc_allow_const_fn_unstable(ptr_metadata)]
pub const fn len(self) -> usize {
metadata(self)
}
Expand Down
2 changes: 0 additions & 2 deletions library/core/src/ptr/non_null.rs
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Expand Up @@ -567,7 +567,6 @@ impl<T: ?Sized> NonNull<T> {
#[must_use]
#[inline(always)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[stable(feature = "non_null_convenience", since = "1.80.0")]
#[rustc_const_stable(feature = "non_null_convenience", since = "1.80.0")]
pub const unsafe fn byte_add(self, count: usize) -> Self {
Expand Down Expand Up @@ -651,7 +650,6 @@ impl<T: ?Sized> NonNull<T> {
#[must_use]
#[inline(always)]
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
#[rustc_allow_const_fn_unstable(set_ptr_value)]
#[stable(feature = "non_null_convenience", since = "1.80.0")]
#[rustc_const_stable(feature = "non_null_convenience", since = "1.80.0")]
pub const unsafe fn byte_sub(self, count: usize) -> Self {
Expand Down
1 change: 0 additions & 1 deletion library/core/src/slice/mod.rs
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Expand Up @@ -111,7 +111,6 @@ impl<T> [T] {
#[lang = "slice_len_fn"]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_slice_len", since = "1.39.0")]
#[rustc_allow_const_fn_unstable(ptr_metadata)]
#[inline]
#[must_use]
pub const fn len(&self) -> usize {
Expand Down
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