Stabilize unchecked_{add,sub,mul}

rust-lang · Mar 15, 2024 · 44502c5 · 44502c5
1 parent fd27e87
commit 44502c5
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Showing 9 changed files with 69 additions and 52 deletions.
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
@@ -165,7 +165,6 @@
 #![feature(try_trait_v2)]
 #![feature(try_with_capacity)]
 #![feature(tuple_trait)]
-#![feature(unchecked_math)]
 #![feature(unicode_internals)]
 #![feature(unsize)]
 #![feature(utf8_chunks)]

diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
@@ -2224,24 +2224,27 @@ extern "rust-intrinsic" {
     /// Returns the result of an unchecked addition, resulting in
     /// undefined behavior when `x + y > T::MAX` or `x + y < T::MIN`.
     ///
-    /// This intrinsic does not have a stable counterpart.
-    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
+    /// The stable counterpart of this intrinsic is `unchecked_add` on the various
+    /// integer types, such as [`u16::unchecked_add`] and [`i64::unchecked_add`].
+    #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_nounwind]
     pub fn unchecked_add<T: Copy>(x: T, y: T) -> T;
 
     /// Returns the result of an unchecked subtraction, resulting in
     /// undefined behavior when `x - y > T::MAX` or `x - y < T::MIN`.
     ///
-    /// This intrinsic does not have a stable counterpart.
-    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
+    /// The stable counterpart of this intrinsic is `unchecked_sub` on the various
+    /// integer types, such as [`u16::unchecked_sub`] and [`i64::unchecked_sub`].
+    #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_nounwind]
     pub fn unchecked_sub<T: Copy>(x: T, y: T) -> T;
 
     /// Returns the result of an unchecked multiplication, resulting in
     /// undefined behavior when `x * y > T::MAX` or `x * y < T::MIN`.
     ///
-    /// This intrinsic does not have a stable counterpart.
-    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
+    /// The stable counterpart of this intrinsic is `unchecked_mul` on the various
+    /// integer types, such as [`u16::unchecked_mul`] and [`i64::unchecked_mul`].
+    #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_nounwind]
     pub fn unchecked_mul<T: Copy>(x: T, y: T) -> T;
 

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
@@ -134,7 +134,6 @@
 #![feature(const_heap)]
 #![feature(const_hint_assert_unchecked)]
 #![feature(const_index_range_slice_index)]
-#![feature(const_int_unchecked_arith)]
 #![feature(const_intrinsic_copy)]
 #![feature(const_intrinsic_forget)]
 #![feature(const_ipv4)]
@@ -193,7 +192,6 @@
 #![feature(str_split_inclusive_remainder)]
 #![feature(str_split_remainder)]
 #![feature(strict_provenance)]
-#![feature(unchecked_math)]
 #![feature(unchecked_shifts)]
 #![feature(utf16_extra)]
 #![feature(utf16_extra_const)]

diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs
@@ -492,21 +492,25 @@ macro_rules! int_impl {
         /// Unchecked integer addition. Computes `self + rhs`, assuming overflow
         /// cannot occur.
         ///
+        /// Calling `x.unchecked_add(y)` is semantically equivalent to calling
+        /// `x.`[`checked_add`]`(y).`[`unwrap_unchecked`]`()`.
+        ///
+        /// If you're just trying to avoid the panic in debug mode, then **do not**
+        /// use this.  Instead, you're looking for [`wrapping_add`].
+        ///
         /// # Safety
         ///
         /// This results in undefined behavior when
         #[doc = concat!("`self + rhs > ", stringify!($SelfT), "::MAX` or `self + rhs < ", stringify!($SelfT), "::MIN`,")]
         /// i.e. when [`checked_add`] would return `None`.
         ///
+        /// [`unwrap_unchecked`]: Option::unwrap_unchecked
         #[doc = concat!("[`checked_add`]: ", stringify!($SelfT), "::checked_add")]
-        #[unstable(
-            feature = "unchecked_math",
-            reason = "niche optimization path",
-            issue = "85122",
-        )]
+        #[doc = concat!("[`wrapping_add`]: ", stringify!($SelfT), "::wrapping_add")]
+        #[stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[rustc_const_unstable(feature = "unchecked_math", issue = "85122")]
         #[inline(always)]
         #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
         pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
@@ -630,21 +634,25 @@ macro_rules! int_impl {
         /// Unchecked integer subtraction. Computes `self - rhs`, assuming overflow
         /// cannot occur.
         ///
+        /// Calling `x.unchecked_sub(y)` is semantically equivalent to calling
+        /// `x.`[`checked_sub`]`(y).`[`unwrap_unchecked`]`()`.
+        ///
+        /// If you're just trying to avoid the panic in debug mode, then **do not**
+        /// use this.  Instead, you're looking for [`wrapping_sub`].
+        ///
         /// # Safety
         ///
         /// This results in undefined behavior when
         #[doc = concat!("`self - rhs > ", stringify!($SelfT), "::MAX` or `self - rhs < ", stringify!($SelfT), "::MIN`,")]
         /// i.e. when [`checked_sub`] would return `None`.
         ///
+        /// [`unwrap_unchecked`]: Option::unwrap_unchecked
         #[doc = concat!("[`checked_sub`]: ", stringify!($SelfT), "::checked_sub")]
-        #[unstable(
-            feature = "unchecked_math",
-            reason = "niche optimization path",
-            issue = "85122",
-        )]
+        #[doc = concat!("[`wrapping_sub`]: ", stringify!($SelfT), "::wrapping_sub")]
+        #[stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[rustc_const_unstable(feature = "unchecked_math", issue = "85122")]
         #[inline(always)]
         #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
         pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
@@ -768,21 +776,25 @@ macro_rules! int_impl {
         /// Unchecked integer multiplication. Computes `self * rhs`, assuming overflow
         /// cannot occur.
         ///
+        /// Calling `x.unchecked_mul(y)` is semantically equivalent to calling
+        /// `x.`[`checked_mul`]`(y).`[`unwrap_unchecked`]`()`.
+        ///
+        /// If you're just trying to avoid the panic in debug mode, then **do not**
+        /// use this.  Instead, you're looking for [`wrapping_mul`].
+        ///
         /// # Safety
         ///
         /// This results in undefined behavior when
         #[doc = concat!("`self * rhs > ", stringify!($SelfT), "::MAX` or `self * rhs < ", stringify!($SelfT), "::MIN`,")]
         /// i.e. when [`checked_mul`] would return `None`.
         ///
+        /// [`unwrap_unchecked`]: Option::unwrap_unchecked
         #[doc = concat!("[`checked_mul`]: ", stringify!($SelfT), "::checked_mul")]
-        #[unstable(
-            feature = "unchecked_math",
-            reason = "niche optimization path",
-            issue = "85122",
-        )]
+        #[doc = concat!("[`wrapping_mul`]: ", stringify!($SelfT), "::wrapping_mul")]
+        #[stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[rustc_const_unstable(feature = "unchecked_math", issue = "85122")]
         #[inline(always)]
         #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
         pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {

diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
@@ -500,21 +500,25 @@ macro_rules! uint_impl {
         /// Unchecked integer addition. Computes `self + rhs`, assuming overflow
         /// cannot occur.
         ///
+        /// Calling `x.unchecked_add(y)` is semantically equivalent to calling
+        /// `x.`[`checked_add`]`(y).`[`unwrap_unchecked`]`()`.
+        ///
+        /// If you're just trying to avoid the panic in debug mode, then **do not**
+        /// use this.  Instead, you're looking for [`wrapping_add`].
+        ///
         /// # Safety
         ///
         /// This results in undefined behavior when
         #[doc = concat!("`self + rhs > ", stringify!($SelfT), "::MAX` or `self + rhs < ", stringify!($SelfT), "::MIN`,")]
         /// i.e. when [`checked_add`] would return `None`.
         ///
+        /// [`unwrap_unchecked`]: Option::unwrap_unchecked
         #[doc = concat!("[`checked_add`]: ", stringify!($SelfT), "::checked_add")]
-        #[unstable(
-            feature = "unchecked_math",
-            reason = "niche optimization path",
-            issue = "85122",
-        )]
+        #[doc = concat!("[`wrapping_add`]: ", stringify!($SelfT), "::wrapping_add")]
+        #[stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[rustc_const_unstable(feature = "unchecked_math", issue = "85122")]
         #[inline(always)]
         #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
         pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
@@ -644,21 +648,25 @@ macro_rules! uint_impl {
         /// Unchecked integer subtraction. Computes `self - rhs`, assuming overflow
         /// cannot occur.
         ///
+        /// Calling `x.unchecked_sub(y)` is semantically equivalent to calling
+        /// `x.`[`checked_sub`]`(y).`[`unwrap_unchecked`]`()`.
+        ///
+        /// If you're just trying to avoid the panic in debug mode, then **do not**
+        /// use this.  Instead, you're looking for [`wrapping_sub`].
+        ///
         /// # Safety
         ///
         /// This results in undefined behavior when
         #[doc = concat!("`self - rhs > ", stringify!($SelfT), "::MAX` or `self - rhs < ", stringify!($SelfT), "::MIN`,")]
         /// i.e. when [`checked_sub`] would return `None`.
         ///
+        /// [`unwrap_unchecked`]: Option::unwrap_unchecked
         #[doc = concat!("[`checked_sub`]: ", stringify!($SelfT), "::checked_sub")]
-        #[unstable(
-            feature = "unchecked_math",
-            reason = "niche optimization path",
-            issue = "85122",
-        )]
+        #[doc = concat!("[`wrapping_sub`]: ", stringify!($SelfT), "::wrapping_sub")]
+        #[stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[rustc_const_unstable(feature = "unchecked_math", issue = "85122")]
         #[inline(always)]
         #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
         pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
@@ -726,21 +734,25 @@ macro_rules! uint_impl {
         /// Unchecked integer multiplication. Computes `self * rhs`, assuming overflow
         /// cannot occur.
         ///
+        /// Calling `x.unchecked_mul(y)` is semantically equivalent to calling
+        /// `x.`[`checked_mul`]`(y).`[`unwrap_unchecked`]`()`.
+        ///
+        /// If you're just trying to avoid the panic in debug mode, then **do not**
+        /// use this.  Instead, you're looking for [`wrapping_mul`].
+        ///
         /// # Safety
         ///
         /// This results in undefined behavior when
         #[doc = concat!("`self * rhs > ", stringify!($SelfT), "::MAX` or `self * rhs < ", stringify!($SelfT), "::MIN`,")]
         /// i.e. when [`checked_mul`] would return `None`.
         ///
+        /// [`unwrap_unchecked`]: Option::unwrap_unchecked
         #[doc = concat!("[`checked_mul`]: ", stringify!($SelfT), "::checked_mul")]
-        #[unstable(
-            feature = "unchecked_math",
-            reason = "niche optimization path",
-            issue = "85122",
-        )]
+        #[doc = concat!("[`wrapping_mul`]: ", stringify!($SelfT), "::wrapping_mul")]
+        #[stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "unchecked_math", since = "CURRENT_RUSTC_VERSION")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[rustc_const_unstable(feature = "unchecked_math", issue = "85122")]
         #[inline(always)]
         #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
         pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {

diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
@@ -1038,8 +1038,6 @@ impl<T: ?Sized> *const T {
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")]
-    // We could always go back to wrapping if unchecked becomes unacceptable
-    #[rustc_allow_const_fn_unstable(const_int_unchecked_arith)]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn sub(self, count: usize) -> Self

diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
@@ -1123,8 +1123,6 @@ impl<T: ?Sized> *mut T {
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")]
-    // We could always go back to wrapping if unchecked becomes unacceptable
-    #[rustc_allow_const_fn_unstable(const_int_unchecked_arith)]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn sub(self, count: usize) -> Self

diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
@@ -702,8 +702,6 @@ impl<T: ?Sized> NonNull<T> {
     #[unstable(feature = "non_null_convenience", issue = "117691")]
     #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
-    // We could always go back to wrapping if unchecked becomes unacceptable
-    #[rustc_allow_const_fn_unstable(const_int_unchecked_arith)]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn sub(self, count: usize) -> Self

diff --git a/tests/ui/consts/const-int-unchecked.rs b/tests/ui/consts/const-int-unchecked.rs
@@ -1,5 +1,4 @@
 #![feature(core_intrinsics)]
-#![feature(const_int_unchecked_arith)]
 
 use std::intrinsics;