Rollup merge of rust-lang#126046 - davidzeng0:mixed_integer_ops_unsig…

…ned_sub, r=Amanieu

Implement `mixed_integer_ops_unsigned_sub`

Implement rust-lang#126043

ACP: rust-lang/libs-team#386 [Accepted]

library/core/src/num/uint_macros.rs

@@ -763,6 +763,33 @@ macro_rules! uint_impl {
             }
         }
 
+        /// Checked subtraction with a signed integer. Computes `self - rhs`,
+        /// returning `None` if overflow occurred.
+        ///
+        /// # Examples
+        ///
+        /// Basic usage:
+        ///
+        /// ```
+        /// #![feature(mixed_integer_ops_unsigned_sub)]
+        #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(2), None);")]
+        #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(-2), Some(3));")]
+        #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_sub_signed(-4), None);")]
+        /// ```
+        #[unstable(feature = "mixed_integer_ops_unsigned_sub", issue = "126043")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        pub const fn checked_sub_signed(self, rhs: $SignedT) -> Option<Self> {
+            let (res, overflow) = self.overflowing_sub_signed(rhs);
+
+            if !overflow {
+                Some(res)
+            } else {
+                None
+            }
+        }
+
         #[doc = concat!(
             "Checked integer subtraction. Computes `self - rhs` and checks if the result fits into an [`",
             stringify!($SignedT), "`], returning `None` if overflow occurred."
@@ -1793,6 +1820,35 @@ macro_rules! uint_impl {
             intrinsics::saturating_sub(self, rhs)
         }
 
+        /// Saturating integer subtraction. Computes `self` - `rhs`, saturating at
+        /// the numeric bounds instead of overflowing.
+        ///
+        /// # Examples
+        ///
+        /// Basic usage:
+        ///
+        /// ```
+        /// #![feature(mixed_integer_ops_unsigned_sub)]
+        #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(2), 0);")]
+        #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(-2), 3);")]
+        #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_sub_signed(-4), ", stringify!($SelfT), "::MAX);")]
+        /// ```
+        #[unstable(feature = "mixed_integer_ops_unsigned_sub", issue = "126043")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        pub const fn saturating_sub_signed(self, rhs: $SignedT) -> Self {
+            let (res, overflow) = self.overflowing_sub_signed(rhs);
+
+            if !overflow {
+                res
+            } else if rhs < 0 {
+                Self::MAX
+            } else {
+                0
+            }
+        }
+
         /// Saturating integer multiplication. Computes `self * rhs`,
         /// saturating at the numeric bounds instead of overflowing.
         ///
@@ -1926,6 +1982,27 @@ macro_rules! uint_impl {
             intrinsics::wrapping_sub(self, rhs)
         }
 
+        /// Wrapping (modular) subtraction with a signed integer. Computes
+        /// `self - rhs`, wrapping around at the boundary of the type.
+        ///
+        /// # Examples
+        ///
+        /// Basic usage:
+        ///
+        /// ```
+        /// #![feature(mixed_integer_ops_unsigned_sub)]
+        #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(2), ", stringify!($SelfT), "::MAX);")]
+        #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(-2), 3);")]
+        #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_sub_signed(-4), 1);")]
+        /// ```
+        #[unstable(feature = "mixed_integer_ops_unsigned_sub", issue = "126043")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        pub const fn wrapping_sub_signed(self, rhs: $SignedT) -> Self {
+            self.wrapping_sub(rhs as Self)
+        }
+
         /// Wrapping (modular) multiplication. Computes `self *
         /// rhs`, wrapping around at the boundary of the type.
         ///
@@ -2378,6 +2455,32 @@ macro_rules! uint_impl {
             (c, b || d)
         }
 
+        /// Calculates `self` - `rhs` with a signed `rhs`
+        ///
+        /// Returns a tuple of the subtraction along with a boolean indicating
+        /// whether an arithmetic overflow would occur. If an overflow would
+        /// have occurred then the wrapped value is returned.
+        ///
+        /// # Examples
+        ///
+        /// Basic usage:
+        ///
+        /// ```
+        /// #![feature(mixed_integer_ops_unsigned_sub)]
+        #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(2), (", stringify!($SelfT), "::MAX, true));")]
+        #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(-2), (3, false));")]
+        #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_sub_signed(-4), (1, true));")]
+        /// ```
+        #[unstable(feature = "mixed_integer_ops_unsigned_sub", issue = "126043")]
+        #[must_use = "this returns the result of the operation, \
+                      without modifying the original"]
+        #[inline]
+        pub const fn overflowing_sub_signed(self, rhs: $SignedT) -> (Self, bool) {
+            let (res, overflow) = self.overflowing_sub(rhs as Self);
+
+            (res, overflow ^ (rhs < 0))
+        }
+
         /// Computes the absolute difference between `self` and `other`.
         ///
         /// # Examples