update comment

Author: Neutron3529

library/core/src/num/int_macros.rs

@@ -2068,10 +2068,14 @@ macro_rules! int_impl {
         pub const fn rem_euclid(self, rhs: Self) -> Self {
             let r = self % rhs;
             if r < 0 {
-                // if rhs is `integer::MIN`, rhs.wrapping_abs() == rhs.wrapping_abs,
-                // thus r.wrapping_add(rhs.wrapping_abs()) == r.wrapping_add(rhs) == r - rhs,
-                // which suits our need.
-                // otherwise, rhs.wrapping_abs() == -rhs, which won't overflow since r is negative.
+                // Semantically equivalent to `if rhs < 0 { r - rhs } else { r + rhs }`.
+                // If `rhs` is not `Self::MIN`, then `r + abs(rhs)` will not overflow
+                // and is clearly equivalent, because `r` is negative.
+                // Otherwise, `rhs` is `Self::MIN`, then we have
+                // `r.wrapping_add(Self::MIN.wrapping_abs())`, which evaluates
+                // to `r.wrapping_add(Self::MIN)`, which is equivalent to
+                // `r - Self::MIN`, which is what we wanted (and will not overflow
+                // for negative `r`).
                 r.wrapping_add(rhs.wrapping_abs())
             } else {
                 r