Merging upstream version 1.67.1+dfsg1.

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

1 files changed, 108 insertions, 38 deletions

diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index 1dc79afe8..7ed7d767f 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs
@@ -55,8 +55,13 @@
 #![allow(missing_docs)]
 
 use crate::marker::DiscriminantKind;
+#[cfg(not(bootstrap))]
+use crate::marker::Tuple;
 use crate::mem;
 
+#[cfg(not(bootstrap))]
+pub mod mir;
+
 // These imports are used for simplifying intra-doc links
 #[allow(unused_imports)]
 #[cfg(all(target_has_atomic = "8", target_has_atomic = "32", target_has_atomic = "ptr"))]
@@ -788,7 +793,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn rustc_peek<T>(_: T) -> T;
 
     /// Aborts the execution of the process.
@@ -806,7 +811,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn abort() -> !;
 
     /// Informs the optimizer that this point in the code is not reachable,
@@ -845,7 +850,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn likely(b: bool) -> bool;
 
     /// Hints to the compiler that branch condition is likely to be false.
@@ -860,7 +865,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn unlikely(b: bool) -> bool;
 
     /// Executes a breakpoint trap, for inspection by a debugger.
@@ -880,7 +885,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn size_of<T>() -> usize;
 
     /// The minimum alignment of a type.
@@ -892,7 +897,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn min_align_of<T>() -> usize;
     /// The preferred alignment of a type.
     ///
@@ -921,7 +926,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn type_name<T: ?Sized>() -> &'static str;
 
     /// Gets an identifier which is globally unique to the specified type. This
@@ -935,7 +940,7 @@ 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)]
+    #[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:
@@ -943,7 +948,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn assert_inhabited<T>();
 
     /// A guard for unsafe functions that cannot ever be executed if `T` does not permit
@@ -951,7 +956,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn assert_zero_valid<T>();
 
     /// A guard for unsafe functions that cannot ever be executed if `T` has invalid
@@ -959,7 +964,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn assert_uninit_valid<T>();
 
     /// Gets a reference to a static `Location` indicating where it was called.
@@ -971,7 +976,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn caller_location() -> &'static crate::panic::Location<'static>;
 
     /// Moves a value out of scope without running drop glue.
@@ -984,7 +989,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn forget<T: ?Sized>(_: T);
 
     /// Reinterprets the bits of a value of one type as another type.
@@ -1264,7 +1269,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn needs_drop<T: ?Sized>() -> bool;
 
     /// Calculates the offset from a pointer.
@@ -1309,7 +1314,7 @@ extern "rust-intrinsic" {
     /// any safety invariants.
     ///
     /// Consider using [`pointer::mask`] instead.
-    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
+    #[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
@@ -1501,7 +1506,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`f32::min`]
-    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
+    #[rustc_safe_intrinsic]
     pub fn minnumf32(x: f32, y: f32) -> f32;
     /// Returns the minimum of two `f64` values.
     ///
@@ -1512,7 +1517,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`f64::min`]
-    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
+    #[rustc_safe_intrinsic]
     pub fn minnumf64(x: f64, y: f64) -> f64;
     /// Returns the maximum of two `f32` values.
     ///
@@ -1523,7 +1528,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`f32::max`]
-    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
+    #[rustc_safe_intrinsic]
     pub fn maxnumf32(x: f32, y: f32) -> f32;
     /// Returns the maximum of two `f64` values.
     ///
@@ -1534,7 +1539,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`f64::max`]
-    #[cfg_attr(not(bootstrap), rustc_safe_intrinsic)]
+    #[rustc_safe_intrinsic]
     pub fn maxnumf64(x: f64, y: f64) -> f64;
 
     /// Copies the sign from `y` to `x` for `f32` values.
@@ -1655,7 +1660,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn ctpop<T: Copy>(x: T) -> T;
 
     /// Returns the number of leading unset bits (zeroes) in an integer type `T`.
@@ -1693,7 +1698,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn ctlz<T: Copy>(x: T) -> T;
 
     /// Like `ctlz`, but extra-unsafe as it returns `undef` when
@@ -1750,7 +1755,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn cttz<T: Copy>(x: T) -> T;
 
     /// Like `cttz`, but extra-unsafe as it returns `undef` when
@@ -1783,7 +1788,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn bswap<T: Copy>(x: T) -> T;
 
     /// Reverses the bits in an integer type `T`.
@@ -1797,7 +1802,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn bitreverse<T: Copy>(x: T) -> T;
 
     /// Performs checked integer addition.
@@ -1811,7 +1816,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn add_with_overflow<T: Copy>(x: T, y: T) -> (T, bool);
 
     /// Performs checked integer subtraction
@@ -1825,7 +1830,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn sub_with_overflow<T: Copy>(x: T, y: T) -> (T, bool);
 
     /// Performs checked integer multiplication
@@ -1839,13 +1844,14 @@ 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)]
+    #[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
     /// `x % y != 0` or `y == 0` or `x == T::MIN && y == -1`
     ///
     /// This intrinsic does not have a stable counterpart.
+    #[rustc_const_unstable(feature = "const_exact_div", issue = "none")]
     pub fn exact_div<T: Copy>(x: T, y: T) -> T;
 
     /// Performs an unchecked division, resulting in undefined behavior
@@ -1914,7 +1920,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn rotate_left<T: Copy>(x: T, y: T) -> T;
 
     /// Performs rotate right.
@@ -1928,7 +1934,7 @@ 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)]
+    #[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.
@@ -1942,7 +1948,7 @@ 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)]
+    #[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.
     ///
@@ -1955,7 +1961,7 @@ 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)]
+    #[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.
     ///
@@ -1968,7 +1974,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn wrapping_mul<T: Copy>(a: T, b: T) -> T;
 
     /// Computes `a + b`, saturating at numeric bounds.
@@ -1982,7 +1988,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn saturating_add<T: Copy>(a: T, b: T) -> T;
     /// Computes `a - b`, saturating at numeric bounds.
     ///
@@ -1995,7 +2001,7 @@ 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)]
+    #[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';
@@ -2008,7 +2014,7 @@ 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)]
+    #[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`;
@@ -2021,7 +2027,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn variant_count<T>() -> usize;
 
     /// Rust's "try catch" construct which invokes the function pointer `try_fn`
@@ -2055,7 +2061,7 @@ 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_attr(not(bootstrap), rustc_safe_intrinsic)]
+    #[rustc_safe_intrinsic]
     pub fn ptr_guaranteed_cmp<T>(ptr: *const T, other: *const T) -> u8;
 
     /// Allocates a block of memory at compile time.
@@ -2106,7 +2112,7 @@ 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)]
+    #[rustc_safe_intrinsic]
     pub fn black_box<T>(dummy: T) -> T;
 
     /// `ptr` must point to a vtable.
@@ -2169,11 +2175,75 @@ 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(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
         G: FnOnce<ARG, Output = RET>,
         F: FnOnce<ARG, Output = RET>;
+
+    /// Selects which function to call depending on the context.
+    ///
+    /// If this function is evaluated at compile-time, then a call to this
+    /// intrinsic will be replaced with a call to `called_in_const`. It gets
+    /// replaced with a call to `called_at_rt` otherwise.
+    ///
+    /// # Type Requirements
+    ///
+    /// The two functions must be both function items. They cannot be function
+    /// pointers or closures. The first function must be a `const fn`.
+    ///
+    /// `arg` will be the tupled arguments that will be passed to either one of
+    /// the two functions, therefore, both functions must accept the same type of
+    /// arguments. Both functions must return RET.
+    ///
+    /// # Safety
+    ///
+    /// The two functions must behave observably equivalent. Safe code in other
+    /// crates may assume that calling a `const fn` at compile-time and at run-time
+    /// produces the same result. A function that produces a different result when
+    /// evaluated at run-time, or has any other observable side-effects, is
+    /// *unsound*.
+    ///
+    /// Here is an example of how this could cause a problem:
+    /// ```no_run
+    /// #![feature(const_eval_select)]
+    /// #![feature(core_intrinsics)]
+    /// use std::hint::unreachable_unchecked;
+    /// use std::intrinsics::const_eval_select;
+    ///
+    /// // Crate A
+    /// pub const fn inconsistent() -> i32 {
+    ///     fn runtime() -> i32 { 1 }
+    ///     const fn compiletime() -> i32 { 2 }
+    ///
+    ///     unsafe {
+    //          // ⚠ This code violates the required equivalence of `compiletime`
+    ///         // and `runtime`.
+    ///         const_eval_select((), compiletime, runtime)
+    ///     }
+    /// }
+    ///
+    /// // Crate B
+    /// const X: i32 = inconsistent();
+    /// let x = inconsistent();
+    /// if x != X { unsafe { unreachable_unchecked(); }}
+    /// ```
+    ///
+    /// This code causes Undefined Behavior when being run, since the
+    /// `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: Tuple, F, G, RET>(
+        arg: ARG,
+        called_in_const: F,
+        called_at_rt: G,
+    ) -> RET
+    where
+        G: FnOnce<ARG, Output = RET>,
+        F: FnOnce<ARG, Output = RET>;
 }
 
 // Some functions are defined here because they accidentally got made