bug#10855 Fix IterableOnceOps.min and .max

Use `Ordering.min` and `.max` to implement
`IterableOnceOps.min` and `.max`, instead of using
`Ordering.lteq` and `.gteq`.

Author: NthPortal

src/library/scala/collection/IterableOnce.scala

@@ -724,7 +724,7 @@ trait IterableOnceOps[+A, +CC[_], +C] extends Any { this: IterableOnce[A] =>
   def min[B >: A](implicit ord: Ordering[B]): A = {
     if (isEmpty)
       throw new UnsupportedOperationException("empty.min")
-    reduceLeft((x, y) => if (ord.lteq(x, y)) x else y)
+    reduceLeft(ord.min)
   }
 
   /** Finds the smallest element.
@@ -761,7 +761,7 @@ trait IterableOnceOps[+A, +CC[_], +C] extends Any { this: IterableOnce[A] =>
   def max[B >: A](implicit ord: Ordering[B]): A = {
     if (isEmpty)
       throw new UnsupportedOperationException("empty.max")
-    reduceLeft((x, y) => if (ord.gteq(x, y)) x else y)
+    reduceLeft(ord.max)
   }
 
   /** Finds the largest element.

test/junit/scala/collection/TraversableOnceTest.scala

@@ -92,4 +92,12 @@ class TraversableOnceTest {
     assert(Seq(1).minByOption(identity) == Some(1), "minByOption on a Non Empty Iterable has value")
   }
 
+  @Test
+  def testMinMaxCorrectness(): Unit = {
+    import Ordering.Double.IeeeOrdering
+    val seq = Seq(5.0, 3.0, Double.NaN, 4.0)
+    assert(seq.min.isNaN)
+    assert(seq.max.isNaN)
+  }
+
 }