library: Stabilize const_ptr_write

Const-stabilizes:
- `write`
- `write_bytes`
- `write_unaligned`

In the following paths:
- `core::ptr`
- `core::ptr::NonNull`
- pointer `<*mut T>`

Const-stabilizes the internal `core::intrinsics`:
- `write_bytes`
- `write_via_move`

Author: workingjubilee

library/alloc/src/lib.rs

@@ -172,7 +172,6 @@
 #![feature(allow_internal_unstable)]
 #![feature(cfg_sanitize)]
 #![feature(const_precise_live_drops)]
-#![feature(const_ptr_write)]
 #![feature(const_try)]
 #![feature(decl_macro)]
 #![feature(dropck_eyepatch)]

library/alloc/tests/lib.rs

@@ -8,7 +8,6 @@
 #![feature(const_heap)]
 #![cfg_attr(bootstrap, feature(const_mut_refs))]
 #![feature(const_slice_from_raw_parts_mut)]
-#![feature(const_ptr_write)]
 #![feature(const_try)]
 #![feature(core_intrinsics)]
 #![feature(extract_if)]

library/core/src/intrinsics.rs

@@ -2636,7 +2636,7 @@ extern "rust-intrinsic" {
     /// This intrinsic can *only* be called where the pointer is a local without
     /// projections (`write_via_move(ptr, x)`, not `write_via_move(*ptr, x)`) so
     /// that it trivially obeys runtime-MIR rules about derefs in operands.
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_nounwind]
     pub fn write_via_move<T>(ptr: *mut T, value: T);
 
@@ -3468,13 +3468,13 @@ pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
 #[doc(alias = "memset")]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_allowed_through_unstable_modules]
-#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+#[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
 #[inline(always)]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 #[rustc_diagnostic_item = "ptr_write_bytes"]
 pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
     extern "rust-intrinsic" {
-        #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+        #[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
         #[rustc_nounwind]
         fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
     }

library/core/src/lib.rs

@@ -142,7 +142,6 @@
 #![feature(const_ptr_as_ref)]
 #![feature(const_ptr_is_null)]
 #![feature(const_ptr_sub_ptr)]
-#![feature(const_ptr_write)]
 #![feature(const_raw_ptr_comparison)]
 #![feature(const_replace)]
 #![feature(const_size_of_val)]

library/core/src/ptr/mod.rs

@@ -1614,7 +1614,7 @@ pub const unsafe fn read_unaligned<T>(src: *const T) -> T {
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+#[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
 #[rustc_diagnostic_item = "ptr_write"]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub const unsafe fn write<T>(dst: *mut T, src: T) {
@@ -1722,7 +1722,8 @@ pub const unsafe fn write<T>(dst: *mut T, src: T) {
 /// ```
 #[inline]
 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
-#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_refs_to_cell))]
+#[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
 #[rustc_diagnostic_item = "ptr_write_unaligned"]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub const unsafe fn write_unaligned<T>(dst: *mut T, src: T) {

library/core/src/ptr/mut_ptr.rs

@@ -1360,7 +1360,7 @@ impl<T: ?Sized> *mut T {
     ///
     /// [`ptr::write`]: crate::ptr::write()
     #[stable(feature = "pointer_methods", since = "1.26.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn write(self, val: T)
@@ -1379,7 +1379,7 @@ impl<T: ?Sized> *mut T {
     /// [`ptr::write_bytes`]: crate::ptr::write_bytes()
     #[doc(alias = "memset")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn write_bytes(self, val: u8, count: usize)
@@ -1420,7 +1420,7 @@ impl<T: ?Sized> *mut T {
     ///
     /// [`ptr::write_unaligned`]: crate::ptr::write_unaligned()
     #[stable(feature = "pointer_methods", since = "1.26.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn write_unaligned(self, val: T)

library/core/src/ptr/non_null.rs

@@ -1014,7 +1014,7 @@ impl<T: ?Sized> NonNull<T> {
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
     pub const unsafe fn write(self, val: T)
     where
         T: Sized,
@@ -1033,7 +1033,7 @@ impl<T: ?Sized> NonNull<T> {
     #[doc(alias = "memset")]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
     pub const unsafe fn write_bytes(self, val: u8, count: usize)
     where
         T: Sized,
@@ -1074,7 +1074,7 @@ impl<T: ?Sized> NonNull<T> {
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "CURRENT_RUSTC_VERSION")]
     pub const unsafe fn write_unaligned(self, val: T)
     where
         T: Sized,

library/core/tests/lib.rs

@@ -31,7 +31,6 @@
 #![feature(const_pin)]
 #![feature(const_pointer_is_aligned)]
 #![feature(const_ptr_as_ref)]
-#![feature(const_ptr_write)]
 #![feature(const_result)]
 #![feature(const_slice_from_ref)]
 #![feature(const_three_way_compare)]

tests/ui/consts/load-preserves-partial-init.rs

@@ -1,6 +1,5 @@
 //@ run-pass
 
-#![feature(const_ptr_write)]
 // issue: https://github.com/rust-lang/rust/issues/69488
 // Loads of partially-initialized data could produce completely-uninitialized results.
 // Test to make sure that we no longer do such a "deinitializing" load.