Fix parameter order for _by() variants of min / max/ minmax in std::cmp

library/core/src/cmp.rs

@@ -1554,6 +1554,9 @@ pub fn min<T: Ord>(v1: T, v2: T) -> T {
 ///
 /// Returns the first argument if the comparison determines them to be equal.
 ///
+/// The parameter order is preserved when calling the `compare` function, i.e. `v1` is
+/// always passed as the first argument and `v2` as the second.
+///
 /// # Examples
 ///
 /// ```
@@ -1574,7 +1577,7 @@ pub fn min<T: Ord>(v1: T, v2: T) -> T {
 #[must_use]
 #[stable(feature = "cmp_min_max_by", since = "1.53.0")]
 pub fn min_by<T, F: FnOnce(&T, &T) -> Ordering>(v1: T, v2: T, compare: F) -> T {
-    if compare(&v2, &v1).is_lt() { v2 } else { v1 }
+    if compare(&v1, &v2).is_le() { v1 } else { v2 }
 }
 
 /// Returns the element that gives the minimum value from the specified function.
@@ -1646,6 +1649,9 @@ pub fn max<T: Ord>(v1: T, v2: T) -> T {
 ///
 /// Returns the second argument if the comparison determines them to be equal.
 ///
+/// The parameter order is preserved when calling the `compare` function, i.e. `v1` is
+/// always passed as the first argument and `v2` as the second.
+///
 /// # Examples
 ///
 /// ```
@@ -1666,7 +1672,7 @@ pub fn max<T: Ord>(v1: T, v2: T) -> T {
 #[must_use]
 #[stable(feature = "cmp_min_max_by", since = "1.53.0")]
 pub fn max_by<T, F: FnOnce(&T, &T) -> Ordering>(v1: T, v2: T, compare: F) -> T {
-    if compare(&v2, &v1).is_lt() { v1 } else { v2 }
+    if compare(&v1, &v2).is_gt() { v1 } else { v2 }
 }
 
 /// Returns the element that gives the maximum value from the specified function.
@@ -1745,6 +1751,9 @@ where
 ///
 /// Returns `[v1, v2]` if the comparison determines them to be equal.
 ///
+/// The parameter order is preserved when calling the `compare` function, i.e. `v1` is
+/// always passed as the first argument and `v2` as the second.
+///
 /// # Examples
 ///
 /// ```
@@ -1769,7 +1778,7 @@ pub fn minmax_by<T, F>(v1: T, v2: T, compare: F) -> [T; 2]
 where
     F: FnOnce(&T, &T) -> Ordering,
 {
-    if compare(&v2, &v1).is_lt() { [v2, v1] } else { [v1, v2] }
+    if compare(&v1, &v2).is_le() { [v1, v2] } else { [v2, v1] }
 }
 
 /// Returns minimum and maximum values with respect to the specified key function.