From 669bba35bcada8d764f74af2b1b6ccd145c1346d Mon Sep 17 00:00:00 2001
From: Som Snytt <som.snytt@gmail.com>
Date: Tue, 1 Nov 2022 07:28:15 -0700
Subject: [PATCH] Restore IterableWrapper equals and hashCode

---
 .../convert/JavaCollectionWrappers.scala      | 10 ++-
 .../scala/collection/convert/EqualsTest.scala | 78 +++++++++++++++++++
 2 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 test/junit/scala/collection/convert/EqualsTest.scala

diff --git a/src/library/scala/collection/convert/JavaCollectionWrappers.scala b/src/library/scala/collection/convert/JavaCollectionWrappers.scala
index 49d6596b1a44..29c3dcbac5db 100644
--- a/src/library/scala/collection/convert/JavaCollectionWrappers.scala
+++ b/src/library/scala/collection/convert/JavaCollectionWrappers.scala
@@ -56,7 +56,15 @@ private[collection] object JavaCollectionWrappers extends Serializable {
   }
 
   @SerialVersionUID(3L)
-  class IterableWrapper[A](val underlying: Iterable[A]) extends ju.AbstractCollection[A] with IterableWrapperTrait[A] with Serializable
+  class IterableWrapper[A](val underlying: Iterable[A]) extends ju.AbstractCollection[A] with IterableWrapperTrait[A] with Serializable {
+    import scala.runtime.Statics._
+    override def equals(other: Any): Boolean =
+      other match {
+        case other: IterableWrapper[_] => underlying.equals(other.underlying)
+        case _ => false
+      }
+    override def hashCode = finalizeHash(mix(mix(0xcafebabe, "IterableWrapper".hashCode), anyHash(underlying)), 1)
+  }
 
   @SerialVersionUID(3L)
   class JIterableWrapper[A](val underlying: jl.Iterable[A])
diff --git a/test/junit/scala/collection/convert/EqualsTest.scala b/test/junit/scala/collection/convert/EqualsTest.scala
new file mode 100644
index 000000000000..b3f9ae17176b
--- /dev/null
+++ b/test/junit/scala/collection/convert/EqualsTest.scala
@@ -0,0 +1,78 @@
+
+package scala.collection.convert
+
+import org.junit.Test
+import org.junit.Assert._
+
+import scala.jdk.CollectionConverters._
+import JavaCollectionWrappers._
+
+import java.util.{AbstractList, AbstractSet, List => JList, Set => JSet}
+
+class JTestList(vs: Int*) extends AbstractList[Int] {
+  def this() = this(Nil: _*)
+  override def size = vs.size
+  override def get(i: Int) = vs(i)
+}
+class JTestSet(vs: Int*) extends AbstractSet[Int] {
+  def this() = this(Nil: _*)
+  require(vs.toSet.size == vs.size)
+  override def size = vs.size
+  override def iterator = vs.iterator.asJava
+}
+
+/** Test that collection wrappers forward equals and hashCode where appropriate. */
+class EqualsTest {
+
+  def jlstOf(vs: Int*): JList[Int] = new JTestList(vs: _*)
+  def jsetOf(vs: Int*): JSet[Int] = new JTestSet(vs: _*)
+
+  // Seq extending AbstractList inherits equals
+
+  @Test def `List as JList has equals`: Unit = {
+    val list = List(1, 2, 3)
+    val jlst = new SeqWrapper(list)
+    assertEquals(jlstOf(1, 2, 3), jlst)
+    assertEquals(jlst, jlstOf(1, 2, 3))
+    assertTrue(jlst == jlstOf(1, 2, 3))
+    assertEquals(jlst.hashCode, jlst.hashCode)
+  }
+
+  @Test def `Set as JSet has equals`: Unit = {
+    val set = Set(1, 2, 3)
+    val jset = new SetWrapper(set)
+    assertEquals(jsetOf(1, 2, 3), jset)
+    assertEquals(jset, jsetOf(1, 2, 3))
+    assertTrue(jset == jsetOf(1, 2, 3))
+    assertEquals(jset.hashCode, jset.hashCode)
+  }
+
+  @Test def `Map as JMap has equals`: Unit = {
+    val map = Map(1 -> "one", 2 -> "two", 3 -> "three")
+    val jmap = new MapWrapper(map)
+    assertEquals(jmap, jmap)
+  }
+
+  @Test def `Anything as Collection is equal to Anything`: Unit = {
+    def set = Set(1, 2, 3)
+    def jset = new IterableWrapper(set)
+    assertTrue(jset == jset)
+    assertEquals(jset, jset)
+    assertNotEquals(jset, set)
+    assertEquals(jset.hashCode, jset.hashCode)
+  }
+
+  @Test def `Iterator wrapper does not compare equal`: Unit = {
+    def it = List(1, 2, 3).iterator
+    def jit = new IteratorWrapper(it)
+    assertNotEquals(jit, jit)
+    assertNotEquals(jit.hashCode, jit.hashCode)
+  }
+
+  @Test def `Anything.asScala Iterable has case equals`: Unit = {
+    def vs = jlstOf(42, 27, 37)
+    def it = new JListWrapper(vs)
+    assertEquals(it, it)
+    assertEquals(it.hashCode, it.hashCode)
+  }
+}