X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=library%2Fcore%2Fsrc%2Fnum%2Fint_macros.rs;h=acd0fea4bc4105a03a1d793098e0a45a866a5166;hb=77e78e28870a3241deadc28e14ba82e9f8548802;hp=21518a3f551807356dbbf2dc484f4af1387490fc;hpb=7e5d477ac555d145ad4dcabd78ef8900f377a017;p=rust.git

diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs
index 21518a3f551..acd0fea4bc4 100644
--- a/library/core/src/num/int_macros.rs
+++ b/library/core/src/num/int_macros.rs
@@ -1538,7 +1538,7 @@ pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
         ///
         /// ```
         /// #![feature(bigint_helper_methods)]
-        /// // Only the  most significant word is signed.
+        /// // Only the most significant word is signed.
         /// //
         #[doc = concat!("//   10  MAX    (a = 10 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
         #[doc = concat!("// + -5    9    (b = -5 × 2^", stringify!($BITS), " + 9)")]
@@ -1625,7 +1625,7 @@ pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
         /// overflow.
         ///
         /// Performs "ternary subtraction" by subtracting both an integer
-        /// operandand a borrow-in bit from `self`, and returns a tuple of the
+        /// operand and a borrow-in bit from `self`, and returns a tuple of the
         /// difference along with a boolean indicating whether an arithmetic
         /// overflow would occur. On overflow, the wrapped value is returned.
         ///
@@ -1646,7 +1646,7 @@ pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
         ///
         /// ```
         /// #![feature(bigint_helper_methods)]
-        /// // Only the  most significant word is signed.
+        /// // Only the most significant word is signed.
         /// //
         #[doc = concat!("//    6    8    (a = 6 × 2^", stringify!($BITS), " + 8)")]
         #[doc = concat!("// - -5    9    (b = -5 × 2^", stringify!($BITS), " + 9)")]
@@ -2574,12 +2574,13 @@ pub const fn abs_diff(self, other: Self) -> $UnsignedT {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
+        #[rustc_allow_const_fn_unstable(const_cmp)]
         pub const fn signum(self) -> Self {
-            match self {
-                n if n > 0 =>  1,
-                0          =>  0,
-                _          => -1,
-            }
+            // Picking the right way to phrase this is complicated
+            // (<https://graphics.stanford.edu/~seander/bithacks.html#CopyIntegerSign>)
+            // so delegate it to `Ord` which is already producing -1/0/+1
+            // exactly like we need and can be the place to deal with the complexity.
+            self.cmp(&0) as _
         }
 
         /// Returns `true` if `self` is positive and `false` if the number is zero or