Merging upstream version 1.66.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 70 insertions, 76 deletions

diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index 11c75e2c9..1dc79afe8 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs
@@ -54,8 +54,6 @@
 )]
 #![allow(missing_docs)]
 
-#[cfg(bootstrap)]
-use crate::marker::Destruct;
 use crate::marker::DiscriminantKind;
 use crate::mem;
 
@@ -790,6 +788,7 @@ extern "rust-intrinsic" {
     /// uninitialized at that point in the control flow.
     ///
     /// This intrinsic should not be used outside of the compiler.
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn rustc_peek<T>(_: T) -> T;
 
     /// Aborts the execution of the process.
@@ -807,6 +806,7 @@ extern "rust-intrinsic" {
     /// On Unix, the
     /// process will probably terminate with a signal like `SIGABRT`, `SIGILL`, `SIGTRAP`, `SIGSEGV` or
     /// `SIGBUS`.  The precise behaviour is not guaranteed and not stable.
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn abort() -> !;
 
     /// Informs the optimizer that this point in the code is not reachable,
@@ -845,6 +845,7 @@ extern "rust-intrinsic" {
     ///
     /// This intrinsic does not have a stable counterpart.
     #[rustc_const_unstable(feature = "const_likely", issue = "none")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn likely(b: bool) -> bool;
 
     /// Hints to the compiler that branch condition is likely to be false.
@@ -859,6 +860,7 @@ extern "rust-intrinsic" {
     ///
     /// This intrinsic does not have a stable counterpart.
     #[rustc_const_unstable(feature = "const_likely", issue = "none")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn unlikely(b: bool) -> bool;
 
     /// Executes a breakpoint trap, for inspection by a debugger.
@@ -878,6 +880,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is [`core::mem::size_of`].
     #[rustc_const_stable(feature = "const_size_of", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn size_of<T>() -> usize;
 
     /// The minimum alignment of a type.
@@ -889,6 +892,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is [`core::mem::align_of`].
     #[rustc_const_stable(feature = "const_min_align_of", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn min_align_of<T>() -> usize;
     /// The preferred alignment of a type.
     ///
@@ -917,6 +921,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is [`core::any::type_name`].
     #[rustc_const_unstable(feature = "const_type_name", issue = "63084")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn type_name<T: ?Sized>() -> &'static str;
 
     /// Gets an identifier which is globally unique to the specified type. This
@@ -930,6 +935,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is [`core::any::TypeId::of`].
     #[rustc_const_unstable(feature = "const_type_id", issue = "77125")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn type_id<T: ?Sized + 'static>() -> u64;
 
     /// A guard for unsafe functions that cannot ever be executed if `T` is uninhabited:
@@ -937,6 +943,7 @@ extern "rust-intrinsic" {
     ///
     /// This intrinsic does not have a stable counterpart.
     #[rustc_const_stable(feature = "const_assert_type", since = "1.59.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn assert_inhabited<T>();
 
     /// A guard for unsafe functions that cannot ever be executed if `T` does not permit
@@ -944,6 +951,7 @@ extern "rust-intrinsic" {
     ///
     /// This intrinsic does not have a stable counterpart.
     #[rustc_const_unstable(feature = "const_assert_type2", issue = "none")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn assert_zero_valid<T>();
 
     /// A guard for unsafe functions that cannot ever be executed if `T` has invalid
@@ -951,6 +959,7 @@ extern "rust-intrinsic" {
     ///
     /// This intrinsic does not have a stable counterpart.
     #[rustc_const_unstable(feature = "const_assert_type2", issue = "none")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn assert_uninit_valid<T>();
 
     /// Gets a reference to a static `Location` indicating where it was called.
@@ -962,6 +971,7 @@ extern "rust-intrinsic" {
     ///
     /// Consider using [`core::panic::Location::caller`] instead.
     #[rustc_const_unstable(feature = "const_caller_location", issue = "76156")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn caller_location() -> &'static crate::panic::Location<'static>;
 
     /// Moves a value out of scope without running drop glue.
@@ -974,6 +984,7 @@ extern "rust-intrinsic" {
     /// Therefore, implementations must not require the user to uphold
     /// any safety invariants.
     #[rustc_const_unstable(feature = "const_intrinsic_forget", issue = "none")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn forget<T: ?Sized>(_: T);
 
     /// Reinterprets the bits of a value of one type as another type.
@@ -983,14 +994,14 @@ extern "rust-intrinsic" {
     /// `transmute` is semantically equivalent to a bitwise move of one type
     /// into another. It copies the bits from the source value into the
     /// destination value, then forgets the original. Note that source and destination
-    /// are passed by-value, which means if `T` or `U` contain padding, that padding
+    /// are passed by-value, which means if `Src` or `Dst` contain padding, that padding
     /// is *not* guaranteed to be preserved by `transmute`.
     ///
     /// Both the argument and the result must be [valid](../../nomicon/what-unsafe-does.html) at
     /// their given type. Violating this condition leads to [undefined behavior][ub]. The compiler
     /// will generate code *assuming that you, the programmer, ensure that there will never be
     /// undefined behavior*. It is therefore your responsibility to guarantee that every value
-    /// passed to `transmute` is valid at both types `T` and `U`. Failing to uphold this condition
+    /// passed to `transmute` is valid at both types `Src` and `Dst`. Failing to uphold this condition
     /// may lead to unexpected and unstable compilation results. This makes `transmute` **incredibly
     /// unsafe**. `transmute` should be the absolute last resort.
     ///
@@ -1001,7 +1012,7 @@ extern "rust-intrinsic" {
     ///
     /// Because `transmute` is a by-value operation, alignment of the *transmuted values
     /// themselves* is not a concern. As with any other function, the compiler already ensures
-    /// both `T` and `U` are properly aligned. However, when transmuting values that *point
+    /// both `Src` and `Dst` are properly aligned. However, when transmuting values that *point
     /// elsewhere* (such as pointers, references, boxes…), the caller has to ensure proper
     /// alignment of the pointed-to values.
     ///
@@ -1237,7 +1248,7 @@ extern "rust-intrinsic" {
     #[rustc_allowed_through_unstable_modules]
     #[rustc_const_stable(feature = "const_transmute", since = "1.56.0")]
     #[rustc_diagnostic_item = "transmute"]
-    pub fn transmute<T, U>(e: T) -> U;
+    pub fn transmute<Src, Dst>(src: Src) -> Dst;
 
     /// Returns `true` if the actual type given as `T` requires drop
     /// glue; returns `false` if the actual type provided for `T`
@@ -1253,6 +1264,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is [`mem::needs_drop`](crate::mem::needs_drop).
     #[rustc_const_stable(feature = "const_needs_drop", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn needs_drop<T: ?Sized>() -> bool;
 
     /// Calculates the offset from a pointer.
@@ -1297,7 +1309,7 @@ extern "rust-intrinsic" {
     /// any safety invariants.
     ///
     /// Consider using [`pointer::mask`] instead.
-    #[cfg(not(bootstrap))]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn ptr_mask<T>(ptr: *const T, mask: usize) -> *const T;
 
     /// Equivalent to the appropriate `llvm.memcpy.p0i8.0i8.*` intrinsic, with
@@ -1489,6 +1501,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`f32::min`]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn minnumf32(x: f32, y: f32) -> f32;
     /// Returns the minimum of two `f64` values.
     ///
@@ -1499,6 +1512,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`f64::min`]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn minnumf64(x: f64, y: f64) -> f64;
     /// Returns the maximum of two `f32` values.
     ///
@@ -1509,6 +1523,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`f32::max`]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn maxnumf32(x: f32, y: f32) -> f32;
     /// Returns the maximum of two `f64` values.
     ///
@@ -1519,6 +1534,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`f64::max`]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn maxnumf64(x: f64, y: f64) -> f64;
 
     /// Copies the sign from `y` to `x` for `f32` values.
@@ -1639,6 +1655,7 @@ extern "rust-intrinsic" {
     /// primitives via the `count_ones` method. For example,
     /// [`u32::count_ones`]
     #[rustc_const_stable(feature = "const_ctpop", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn ctpop<T: Copy>(x: T) -> T;
 
     /// Returns the number of leading unset bits (zeroes) in an integer type `T`.
@@ -1676,6 +1693,7 @@ extern "rust-intrinsic" {
     /// assert_eq!(num_leading, 16);
     /// ```
     #[rustc_const_stable(feature = "const_ctlz", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn ctlz<T: Copy>(x: T) -> T;
 
     /// Like `ctlz`, but extra-unsafe as it returns `undef` when
@@ -1732,6 +1750,7 @@ extern "rust-intrinsic" {
     /// assert_eq!(num_trailing, 16);
     /// ```
     #[rustc_const_stable(feature = "const_cttz", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn cttz<T: Copy>(x: T) -> T;
 
     /// Like `cttz`, but extra-unsafe as it returns `undef` when
@@ -1764,6 +1783,7 @@ extern "rust-intrinsic" {
     /// primitives via the `swap_bytes` method. For example,
     /// [`u32::swap_bytes`]
     #[rustc_const_stable(feature = "const_bswap", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn bswap<T: Copy>(x: T) -> T;
 
     /// Reverses the bits in an integer type `T`.
@@ -1777,6 +1797,7 @@ extern "rust-intrinsic" {
     /// primitives via the `reverse_bits` method. For example,
     /// [`u32::reverse_bits`]
     #[rustc_const_stable(feature = "const_bitreverse", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn bitreverse<T: Copy>(x: T) -> T;
 
     /// Performs checked integer addition.
@@ -1790,6 +1811,7 @@ extern "rust-intrinsic" {
     /// primitives via the `overflowing_add` method. For example,
     /// [`u32::overflowing_add`]
     #[rustc_const_stable(feature = "const_int_overflow", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn add_with_overflow<T: Copy>(x: T, y: T) -> (T, bool);
 
     /// Performs checked integer subtraction
@@ -1803,6 +1825,7 @@ extern "rust-intrinsic" {
     /// primitives via the `overflowing_sub` method. For example,
     /// [`u32::overflowing_sub`]
     #[rustc_const_stable(feature = "const_int_overflow", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn sub_with_overflow<T: Copy>(x: T, y: T) -> (T, bool);
 
     /// Performs checked integer multiplication
@@ -1816,6 +1839,7 @@ extern "rust-intrinsic" {
     /// primitives via the `overflowing_mul` method. For example,
     /// [`u32::overflowing_mul`]
     #[rustc_const_stable(feature = "const_int_overflow", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn mul_with_overflow<T: Copy>(x: T, y: T) -> (T, bool);
 
     /// Performs an exact division, resulting in undefined behavior where
@@ -1890,6 +1914,7 @@ extern "rust-intrinsic" {
     /// primitives via the `rotate_left` method. For example,
     /// [`u32::rotate_left`]
     #[rustc_const_stable(feature = "const_int_rotate", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn rotate_left<T: Copy>(x: T, y: T) -> T;
 
     /// Performs rotate right.
@@ -1903,6 +1928,7 @@ extern "rust-intrinsic" {
     /// primitives via the `rotate_right` method. For example,
     /// [`u32::rotate_right`]
     #[rustc_const_stable(feature = "const_int_rotate", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn rotate_right<T: Copy>(x: T, y: T) -> T;
 
     /// Returns (a + b) mod 2<sup>N</sup>, where N is the width of T in bits.
@@ -1916,6 +1942,7 @@ extern "rust-intrinsic" {
     /// primitives via the `wrapping_add` method. For example,
     /// [`u32::wrapping_add`]
     #[rustc_const_stable(feature = "const_int_wrapping", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn wrapping_add<T: Copy>(a: T, b: T) -> T;
     /// Returns (a - b) mod 2<sup>N</sup>, where N is the width of T in bits.
     ///
@@ -1928,6 +1955,7 @@ extern "rust-intrinsic" {
     /// primitives via the `wrapping_sub` method. For example,
     /// [`u32::wrapping_sub`]
     #[rustc_const_stable(feature = "const_int_wrapping", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn wrapping_sub<T: Copy>(a: T, b: T) -> T;
     /// Returns (a * b) mod 2<sup>N</sup>, where N is the width of T in bits.
     ///
@@ -1940,6 +1968,7 @@ extern "rust-intrinsic" {
     /// primitives via the `wrapping_mul` method. For example,
     /// [`u32::wrapping_mul`]
     #[rustc_const_stable(feature = "const_int_wrapping", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn wrapping_mul<T: Copy>(a: T, b: T) -> T;
 
     /// Computes `a + b`, saturating at numeric bounds.
@@ -1953,6 +1982,7 @@ extern "rust-intrinsic" {
     /// primitives via the `saturating_add` method. For example,
     /// [`u32::saturating_add`]
     #[rustc_const_stable(feature = "const_int_saturating", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn saturating_add<T: Copy>(a: T, b: T) -> T;
     /// Computes `a - b`, saturating at numeric bounds.
     ///
@@ -1965,6 +1995,7 @@ extern "rust-intrinsic" {
     /// primitives via the `saturating_sub` method. For example,
     /// [`u32::saturating_sub`]
     #[rustc_const_stable(feature = "const_int_saturating", since = "1.40.0")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn saturating_sub<T: Copy>(a: T, b: T) -> T;
 
     /// Returns the value of the discriminant for the variant in 'v';
@@ -1977,6 +2008,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is [`core::mem::discriminant`].
     #[rustc_const_unstable(feature = "const_discriminant", issue = "69821")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn discriminant_value<T>(v: &T) -> <T as DiscriminantKind>::Discriminant;
 
     /// Returns the number of variants of the type `T` cast to a `usize`;
@@ -1989,6 +2021,7 @@ extern "rust-intrinsic" {
     ///
     /// The to-be-stabilized version of this intrinsic is [`mem::variant_count`].
     #[rustc_const_unstable(feature = "variant_count", issue = "73662")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn variant_count<T>() -> usize;
 
     /// Rust's "try catch" construct which invokes the function pointer `try_fn`
@@ -2022,17 +2055,9 @@ extern "rust-intrinsic" {
     /// Therefore, implementations must not require the user to uphold
     /// any safety invariants.
     #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
-    #[cfg(not(bootstrap))]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn ptr_guaranteed_cmp<T>(ptr: *const T, other: *const T) -> u8;
 
-    #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
-    #[cfg(bootstrap)]
-    pub fn ptr_guaranteed_eq<T>(ptr: *const T, other: *const T) -> bool;
-
-    #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
-    #[cfg(bootstrap)]
-    pub fn ptr_guaranteed_ne<T>(ptr: *const T, other: *const T) -> bool;
-
     /// Allocates a block of memory at compile time.
     /// At runtime, just returns a null pointer.
     ///
@@ -2081,6 +2106,7 @@ extern "rust-intrinsic" {
     ///
     /// [`std::hint::black_box`]: crate::hint::black_box
     #[rustc_const_unstable(feature = "const_black_box", issue = "none")]
+    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
     pub fn black_box<T>(dummy: T) -> T;
 
     /// `ptr` must point to a vtable.
@@ -2143,7 +2169,6 @@ extern "rust-intrinsic" {
     /// `unreachable_unchecked` is actually being reached. The bug is in *crate A*,
     /// which violates the principle that a `const fn` must behave the same at
     /// compile-time and at run-time. The unsafe code in crate B is fine.
-    #[cfg(not(bootstrap))]
     #[rustc_const_unstable(feature = "const_eval_select", issue = "none")]
     pub fn const_eval_select<ARG, F, G, RET>(arg: ARG, called_in_const: F, called_at_rt: G) -> RET
     where
@@ -2178,15 +2203,17 @@ extern "rust-intrinsic" {
 /// the occasional mistake, and this check should help them figure things out.
 #[allow_internal_unstable(const_eval_select)] // permit this to be called in stably-const fn
 macro_rules! assert_unsafe_precondition {
-    ($([$($tt:tt)*])?($($i:ident:$ty:ty),*$(,)?) => $e:expr) => {
+    ($name:expr, $([$($tt:tt)*])?($($i:ident:$ty:ty),*$(,)?) => $e:expr) => {
         if cfg!(debug_assertions) {
             // allow non_snake_case to allow capturing const generics
             #[allow(non_snake_case)]
             #[inline(always)]
             fn runtime$(<$($tt)*>)?($($i:$ty),*) {
                 if !$e {
-                    // abort instead of panicking to reduce impact on code size
-                    ::core::intrinsics::abort();
+                    // don't unwind to reduce impact on code size
+                    ::core::panicking::panic_str_nounwind(
+                        concat!("unsafe precondition(s) violated: ", $name)
+                    );
                 }
             }
             #[allow(non_snake_case)]
@@ -2204,6 +2231,16 @@ pub(crate) fn is_aligned_and_not_null<T>(ptr: *const T) -> bool {
     !ptr.is_null() && ptr.is_aligned()
 }
 
+/// Checks whether an allocation of `len` instances of `T` exceeds
+/// the maximum allowed allocation size.
+pub(crate) fn is_valid_allocation_size<T>(len: usize) -> bool {
+    let max_len = const {
+        let size = crate::mem::size_of::<T>();
+        if size == 0 { usize::MAX } else { isize::MAX as usize / size }
+    };
+    len <= max_len
+}
+
 /// Checks whether the regions of memory starting at `src` and `dst` of size
 /// `count * size_of::<T>()` do *not* overlap.
 pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -> bool {
@@ -2216,16 +2253,6 @@ pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -
     diff >= size
 }
 
-#[cfg(bootstrap)]
-pub const fn ptr_guaranteed_cmp(a: *const (), b: *const ()) -> u8 {
-    match (ptr_guaranteed_eq(a, b), ptr_guaranteed_ne(a, b)) {
-        (false, false) => 2,
-        (true, false) => 1,
-        (false, true) => 0,
-        (true, true) => unreachable!(),
-    }
-}
-
 /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source
 /// and destination must *not* overlap.
 ///
@@ -2325,7 +2352,10 @@ pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: us
     // SAFETY: the safety contract for `copy_nonoverlapping` must be
     // upheld by the caller.
     unsafe {
-        assert_unsafe_precondition!([T](src: *const T, dst: *mut T, count: usize) =>
+        assert_unsafe_precondition!(
+            "ptr::copy_nonoverlapping requires that both pointer arguments are aligned and non-null \
+            and the specified memory ranges do not overlap",
+            [T](src: *const T, dst: *mut T, count: usize) =>
             is_aligned_and_not_null(src)
                 && is_aligned_and_not_null(dst)
                 && is_nonoverlapping(src, dst, count)
@@ -2411,8 +2441,11 @@ pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
 
     // SAFETY: the safety contract for `copy` must be upheld by the caller.
     unsafe {
-        assert_unsafe_precondition!([T](src: *const T, dst: *mut T) =>
-            is_aligned_and_not_null(src) && is_aligned_and_not_null(dst));
+        assert_unsafe_precondition!(
+            "ptr::copy requires that both pointer arguments are aligned aligned and non-null",
+            [T](src: *const T, dst: *mut T) =>
+            is_aligned_and_not_null(src) && is_aligned_and_not_null(dst)
+        );
         copy(src, dst, count)
     }
 }
@@ -2480,49 +2513,10 @@ pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
 
     // SAFETY: the safety contract for `write_bytes` must be upheld by the caller.
     unsafe {
-        assert_unsafe_precondition!([T](dst: *mut T) => is_aligned_and_not_null(dst));
+        assert_unsafe_precondition!(
+            "ptr::write_bytes requires that the destination pointer is aligned and non-null",
+            [T](dst: *mut T) => is_aligned_and_not_null(dst)
+        );
         write_bytes(dst, val, count)
     }
 }
-
-#[cfg(bootstrap)]
-#[unstable(
-    feature = "const_eval_select",
-    issue = "none",
-    reason = "const_eval_select will never be stable"
-)]
-#[rustc_const_unstable(feature = "const_eval_select", issue = "none")]
-#[lang = "const_eval_select"]
-#[rustc_do_not_const_check]
-#[inline]
-pub const unsafe fn const_eval_select<ARG, F, G, RET>(
-    arg: ARG,
-    _called_in_const: F,
-    called_at_rt: G,
-) -> RET
-where
-    F: ~const FnOnce<ARG, Output = RET>,
-    G: FnOnce<ARG, Output = RET> + ~const Destruct,
-{
-    called_at_rt.call_once(arg)
-}
-
-#[cfg(bootstrap)]
-#[unstable(
-    feature = "const_eval_select",
-    issue = "none",
-    reason = "const_eval_select will never be stable"
-)]
-#[rustc_const_unstable(feature = "const_eval_select", issue = "none")]
-#[lang = "const_eval_select_ct"]
-pub const unsafe fn const_eval_select_ct<ARG, F, G, RET>(
-    arg: ARG,
-    called_in_const: F,
-    _called_at_rt: G,
-) -> RET
-where
-    F: ~const FnOnce<ARG, Output = RET>,
-    G: FnOnce<ARG, Output = RET> + ~const Destruct,
-{
-    called_in_const.call_once(arg)
-}