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tgross35tgross35
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Rollup merge of rust-lang#130966 - RalfJung:ptr-metadata-const-stable, r=scottmcm
make ptr metadata functions callable from stable const fn So far this was done with a bunch of `rustc_allow_const_fn_unstable`. But those should be the exception, not the norm. If we are confident we can expose the ptr metadata APIs *indirectly* in stable const fn, we should just mark them as `rustc_const_stable`. And we better be confident we can do that since it's already been done a while ago. ;) In particular this marks two intrinsics as const-stable: `aggregate_raw_ptr`, `ptr_metadata`. This should be uncontroversial, they are trivial to implement in the interpreter. Cc `@rust-lang/wg-const-eval` `@rust-lang/lang`
2 parents 40d0ada + 7650307 commit a063759

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10 files changed

+77
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lines changed

10 files changed

+77
-29
lines changed

‎library/core/src/intrinsics.rs‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -3165,7 +3165,7 @@ pub const fn type_id<T: ?Sized + 'static>() -> u128 {
31653165
/// change the possible layouts of pointers.
31663166
#[rustc_nounwind]
31673167
#[unstable(feature = "core_intrinsics", issue = "none")]
3168-
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
3168+
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
31693169
#[rustc_intrinsic]
31703170
#[rustc_intrinsic_must_be_overridden]
31713171
pub const fn aggregate_raw_ptr<P: AggregateRawPtr<D, Metadata = M>, D, M>(_data: D, _meta: M) -> P {
@@ -3190,7 +3190,7 @@ impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*mut T> for *mut P {
31903190
/// This is used to implement functions like `ptr::metadata`.
31913191
#[rustc_nounwind]
31923192
#[unstable(feature = "core_intrinsics", issue = "none")]
3193-
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
3193+
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
31943194
#[rustc_intrinsic]
31953195
#[rustc_intrinsic_must_be_overridden]
31963196
pub const fn ptr_metadata<P: ptr::Pointee<Metadata = M> + ?Sized, M>(_ptr: *const P) -> M {

‎library/core/src/ptr/const_ptr.rs‎

Lines changed: 1 addition & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -92,7 +92,7 @@ impl<T: ?Sized> *const T {
9292
/// }
9393
/// ```
9494
#[unstable(feature = "set_ptr_value", issue = "75091")]
95-
#[rustc_const_unstable(feature = "set_ptr_value", issue = "75091")]
95+
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
9696
#[must_use = "returns a new pointer rather than modifying its argument"]
9797
#[inline]
9898
pub const fn with_metadata_of<U>(self, meta: *const U) -> *const U
@@ -412,7 +412,6 @@ impl<T: ?Sized> *const T {
412412
#[inline(always)]
413413
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
414414
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
415-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
416415
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
417416
pub const unsafe fn byte_offset(self, count: isize) -> Self {
418417
// SAFETY: the caller must uphold the safety contract for `offset`.
@@ -495,7 +494,6 @@ impl<T: ?Sized> *const T {
495494
#[inline(always)]
496495
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
497496
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
498-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
499497
pub const fn wrapping_byte_offset(self, count: isize) -> Self {
500498
self.cast::<u8>().wrapping_offset(count).with_metadata_of(self)
501499
}
@@ -645,7 +643,6 @@ impl<T: ?Sized> *const T {
645643
#[inline(always)]
646644
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
647645
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
648-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
649646
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
650647
pub const unsafe fn byte_offset_from<U: ?Sized>(self, origin: *const U) -> isize {
651648
// SAFETY: the caller must uphold the safety contract for `offset_from`.
@@ -873,7 +870,6 @@ impl<T: ?Sized> *const T {
873870
#[inline(always)]
874871
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
875872
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
876-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
877873
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
878874
pub const unsafe fn byte_add(self, count: usize) -> Self {
879875
// SAFETY: the caller must uphold the safety contract for `add`.
@@ -956,7 +952,6 @@ impl<T: ?Sized> *const T {
956952
#[inline(always)]
957953
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
958954
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
959-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
960955
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
961956
pub const unsafe fn byte_sub(self, count: usize) -> Self {
962957
// SAFETY: the caller must uphold the safety contract for `sub`.
@@ -1039,7 +1034,6 @@ impl<T: ?Sized> *const T {
10391034
#[inline(always)]
10401035
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
10411036
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
1042-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
10431037
pub const fn wrapping_byte_add(self, count: usize) -> Self {
10441038
self.cast::<u8>().wrapping_add(count).with_metadata_of(self)
10451039
}
@@ -1120,7 +1114,6 @@ impl<T: ?Sized> *const T {
11201114
#[inline(always)]
11211115
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
11221116
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
1123-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
11241117
pub const fn wrapping_byte_sub(self, count: usize) -> Self {
11251118
self.cast::<u8>().wrapping_sub(count).with_metadata_of(self)
11261119
}
@@ -1554,7 +1547,6 @@ impl<T> *const [T] {
15541547
#[inline]
15551548
#[stable(feature = "slice_ptr_len", since = "1.79.0")]
15561549
#[rustc_const_stable(feature = "const_slice_ptr_len", since = "1.79.0")]
1557-
#[rustc_allow_const_fn_unstable(ptr_metadata)]
15581550
pub const fn len(self) -> usize {
15591551
metadata(self)
15601552
}

‎library/core/src/ptr/metadata.rs‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -92,7 +92,7 @@ pub trait Thin = Pointee<Metadata = ()>;
9292
///
9393
/// assert_eq!(std::ptr::metadata("foo"), 3_usize);
9494
/// ```
95-
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
95+
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
9696
#[inline]
9797
pub const fn metadata<T: ?Sized>(ptr: *const T) -> <T as Pointee>::Metadata {
9898
ptr_metadata(ptr)
@@ -106,7 +106,7 @@ pub const fn metadata<T: ?Sized>(ptr: *const T) -> <T as Pointee>::Metadata {
106106
///
107107
/// [`slice::from_raw_parts`]: crate::slice::from_raw_parts
108108
#[unstable(feature = "ptr_metadata", issue = "81513")]
109-
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
109+
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
110110
#[inline]
111111
pub const fn from_raw_parts<T: ?Sized>(
112112
data_pointer: *const impl Thin,
@@ -120,7 +120,7 @@ pub const fn from_raw_parts<T: ?Sized>(
120120
///
121121
/// See the documentation of [`from_raw_parts`] for more details.
122122
#[unstable(feature = "ptr_metadata", issue = "81513")]
123-
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
123+
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
124124
#[inline]
125125
pub const fn from_raw_parts_mut<T: ?Sized>(
126126
data_pointer: *mut impl Thin,

‎library/core/src/ptr/mod.rs‎

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -599,7 +599,6 @@ pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
599599
#[stable(feature = "rust1", since = "1.0.0")]
600600
#[rustc_promotable]
601601
#[rustc_const_stable(feature = "const_ptr_null", since = "1.24.0")]
602-
#[rustc_allow_const_fn_unstable(ptr_metadata)]
603602
#[rustc_diagnostic_item = "ptr_null"]
604603
pub const fn null<T: ?Sized + Thin>() -> *const T {
605604
from_raw_parts(without_provenance::<()>(0), ())
@@ -625,7 +624,6 @@ pub const fn null<T: ?Sized + Thin>() -> *const T {
625624
#[stable(feature = "rust1", since = "1.0.0")]
626625
#[rustc_promotable]
627626
#[rustc_const_stable(feature = "const_ptr_null", since = "1.24.0")]
628-
#[rustc_allow_const_fn_unstable(ptr_metadata)]
629627
#[rustc_diagnostic_item = "ptr_null_mut"]
630628
pub const fn null_mut<T: ?Sized + Thin>() -> *mut T {
631629
from_raw_parts_mut(without_provenance_mut::<()>(0), ())
@@ -949,7 +947,6 @@ pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T {
949947
#[inline]
950948
#[stable(feature = "slice_from_raw_parts", since = "1.42.0")]
951949
#[rustc_const_stable(feature = "const_slice_from_raw_parts", since = "1.64.0")]
952-
#[rustc_allow_const_fn_unstable(ptr_metadata)]
953950
#[rustc_diagnostic_item = "ptr_slice_from_raw_parts"]
954951
pub const fn slice_from_raw_parts<T>(data: *const T, len: usize) -> *const [T] {
955952
from_raw_parts(data, len)

‎library/core/src/ptr/mut_ptr.rs‎

Lines changed: 1 addition & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -74,7 +74,7 @@ impl<T: ?Sized> *mut T {
7474
/// }
7575
/// ```
7676
#[unstable(feature = "set_ptr_value", issue = "75091")]
77-
#[rustc_const_unstable(feature = "set_ptr_value", issue = "75091")]
77+
#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
7878
#[must_use = "returns a new pointer rather than modifying its argument"]
7979
#[inline]
8080
pub const fn with_metadata_of<U>(self, meta: *const U) -> *mut U
@@ -412,7 +412,6 @@ impl<T: ?Sized> *mut T {
412412
#[inline(always)]
413413
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
414414
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
415-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
416415
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
417416
pub const unsafe fn byte_offset(self, count: isize) -> Self {
418417
// SAFETY: the caller must uphold the safety contract for `offset`.
@@ -492,7 +491,6 @@ impl<T: ?Sized> *mut T {
492491
#[inline(always)]
493492
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
494493
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
495-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
496494
pub const fn wrapping_byte_offset(self, count: isize) -> Self {
497495
self.cast::<u8>().wrapping_offset(count).with_metadata_of(self)
498496
}
@@ -808,7 +806,6 @@ impl<T: ?Sized> *mut T {
808806
#[inline(always)]
809807
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
810808
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
811-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
812809
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
813810
pub const unsafe fn byte_offset_from<U: ?Sized>(self, origin: *const U) -> isize {
814811
// SAFETY: the caller must uphold the safety contract for `offset_from`.
@@ -954,7 +951,6 @@ impl<T: ?Sized> *mut T {
954951
#[inline(always)]
955952
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
956953
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
957-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
958954
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
959955
pub const unsafe fn byte_add(self, count: usize) -> Self {
960956
// SAFETY: the caller must uphold the safety contract for `add`.
@@ -1037,7 +1033,6 @@ impl<T: ?Sized> *mut T {
10371033
#[inline(always)]
10381034
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
10391035
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
1040-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
10411036
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
10421037
pub const unsafe fn byte_sub(self, count: usize) -> Self {
10431038
// SAFETY: the caller must uphold the safety contract for `sub`.
@@ -1118,7 +1113,6 @@ impl<T: ?Sized> *mut T {
11181113
#[inline(always)]
11191114
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
11201115
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
1121-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
11221116
pub const fn wrapping_byte_add(self, count: usize) -> Self {
11231117
self.cast::<u8>().wrapping_add(count).with_metadata_of(self)
11241118
}
@@ -1197,7 +1191,6 @@ impl<T: ?Sized> *mut T {
11971191
#[inline(always)]
11981192
#[stable(feature = "pointer_byte_offsets", since = "1.75.0")]
11991193
#[rustc_const_stable(feature = "const_pointer_byte_offsets", since = "1.75.0")]
1200-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
12011194
pub const fn wrapping_byte_sub(self, count: usize) -> Self {
12021195
self.cast::<u8>().wrapping_sub(count).with_metadata_of(self)
12031196
}
@@ -1804,7 +1797,6 @@ impl<T> *mut [T] {
18041797
#[inline(always)]
18051798
#[stable(feature = "slice_ptr_len", since = "1.79.0")]
18061799
#[rustc_const_stable(feature = "const_slice_ptr_len", since = "1.79.0")]
1807-
#[rustc_allow_const_fn_unstable(ptr_metadata)]
18081800
pub const fn len(self) -> usize {
18091801
metadata(self)
18101802
}

‎library/core/src/ptr/non_null.rs‎

Lines changed: 0 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -567,7 +567,6 @@ impl<T: ?Sized> NonNull<T> {
567567
#[must_use]
568568
#[inline(always)]
569569
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
570-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
571570
#[stable(feature = "non_null_convenience", since = "1.80.0")]
572571
#[rustc_const_stable(feature = "non_null_convenience", since = "1.80.0")]
573572
pub const unsafe fn byte_add(self, count: usize) -> Self {
@@ -651,7 +650,6 @@ impl<T: ?Sized> NonNull<T> {
651650
#[must_use]
652651
#[inline(always)]
653652
#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
654-
#[rustc_allow_const_fn_unstable(set_ptr_value)]
655653
#[stable(feature = "non_null_convenience", since = "1.80.0")]
656654
#[rustc_const_stable(feature = "non_null_convenience", since = "1.80.0")]
657655
pub const unsafe fn byte_sub(self, count: usize) -> Self {

‎library/core/src/slice/mod.rs‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -111,7 +111,6 @@ impl<T> [T] {
111111
#[lang = "slice_len_fn"]
112112
#[stable(feature = "rust1", since = "1.0.0")]
113113
#[rustc_const_stable(feature = "const_slice_len", since = "1.39.0")]
114-
#[rustc_allow_const_fn_unstable(ptr_metadata)]
115114
#[inline]
116115
#[must_use]
117116
pub const fn len(&self) -> usize {

‎tests/ui/consts/auxiliary/unstable_but_const_stable.rs‎

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,13 @@
1+
#![feature(staged_api, rustc_attrs, intrinsics)]
2+
#![stable(since="1.0.0", feature = "stable")]
3+
4+
extern "rust-intrinsic" {
5+
#[unstable(feature = "unstable", issue = "42")]
6+
#[rustc_const_stable(feature = "stable", since = "1.0.0")]
7+
#[rustc_nounwind]
8+
pub fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
9+
}
10+
11+
#[unstable(feature = "unstable", issue = "42")]
12+
#[rustc_const_stable(feature = "stable", since = "1.0.0")]
13+
pub const fn some_unstable_fn() {}

‎tests/ui/consts/unstable-const-stable.rs‎

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
//@ aux-build:unstable_but_const_stable.rs
2+
3+
extern crate unstable_but_const_stable;
4+
use unstable_but_const_stable::*;
5+
6+
fn main() {
7+
some_unstable_fn(); //~ERROR use of unstable library feature
8+
unsafe { write_bytes(4 as *mut u8, 0, 0) }; //~ERROR use of unstable library feature
9+
}
10+
11+
const fn const_main() {
12+
some_unstable_fn(); //~ERROR use of unstable library feature
13+
unsafe { write_bytes(4 as *mut u8, 0, 0) }; //~ERROR use of unstable library feature
14+
}

‎tests/ui/consts/unstable-const-stable.stderr‎

Lines changed: 43 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,43 @@
1+
error[E0658]: use of unstable library feature 'unstable'
2+
--> $DIR/unstable-const-stable.rs:7:5
3+
|
4+
LL | some_unstable_fn();
5+
| ^^^^^^^^^^^^^^^^
6+
|
7+
= note: see issue #42 <https://github.com/rust-lang/rust/issues/42> for more information
8+
= help: add `#![feature(unstable)]` to the crate attributes to enable
9+
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
10+
11+
error[E0658]: use of unstable library feature 'unstable'
12+
--> $DIR/unstable-const-stable.rs:8:14
13+
|
14+
LL | unsafe { write_bytes(4 as *mut u8, 0, 0) };
15+
| ^^^^^^^^^^^
16+
|
17+
= note: see issue #42 <https://github.com/rust-lang/rust/issues/42> for more information
18+
= help: add `#![feature(unstable)]` to the crate attributes to enable
19+
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
20+
21+
error[E0658]: use of unstable library feature 'unstable'
22+
--> $DIR/unstable-const-stable.rs:12:5
23+
|
24+
LL | some_unstable_fn();
25+
| ^^^^^^^^^^^^^^^^
26+
|
27+
= note: see issue #42 <https://github.com/rust-lang/rust/issues/42> for more information
28+
= help: add `#![feature(unstable)]` to the crate attributes to enable
29+
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
30+
31+
error[E0658]: use of unstable library feature 'unstable'
32+
--> $DIR/unstable-const-stable.rs:13:14
33+
|
34+
LL | unsafe { write_bytes(4 as *mut u8, 0, 0) };
35+
| ^^^^^^^^^^^
36+
|
37+
= note: see issue #42 <https://github.com/rust-lang/rust/issues/42> for more information
38+
= help: add `#![feature(unstable)]` to the crate attributes to enable
39+
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
40+
41+
error: aborting due to 4 previous errors
42+
43+
For more information about this error, try `rustc --explain E0658`.

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