Fix MutableMap.entries.contains(Map.Entry)

#KT-42428 Fixed.

kotlin-native/backend.native/tests/stdlib_external/collections/KT42428Test.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package test.collections
+
+import kotlin.test.*
+
+// TODO: consider moving to common stdlib tests.
+class KT42428Test {
+
+    private val listOfLetterIndexPairs = ('a'..'z').withIndex().map { (i, c) -> "$c" to i }
+
+    private val mapOfLetterToIndex = listOfLetterIndexPairs.toMap()
+
+    @Test fun testListOfPairsToMapEntriesContainsMapEntry() {
+        testMapEntriesContainsMapEntry(listOfLetterIndexPairs.toMap(), "h", 7)
+    }
+
+    @Test fun testMapToMutableMapEntriesContainsMapEntry() {
+        testMapEntriesContainsMapEntry(mapOfLetterToIndex.toMutableMap(), "h", 7)
+    }
+
+    @Test fun testHashMapEntriesContainsMapEntry() {
+        testMapEntriesContainsMapEntry(HashMap(mapOfLetterToIndex), "h", 7)
+    }
+
+    @Test fun testLinkedHashMapEntriesContainsMapEntry() {
+        testMapEntriesContainsMapEntry(LinkedHashMap(mapOfLetterToIndex), "h", 7)
+    }
+
+    // Based on https://youtrack.jetbrains.com/issue/KT-42428.
+    private fun testMapEntriesContainsMapEntry(map: Map<String, Int>, key: String, value: Int) {
+        data class SimpleEntry<out K, out V>(override val key: K, override val value: V) : Map.Entry<K, V> {
+
+            override fun equals(other: Any?): Boolean =
+                    other is Map.Entry<*, *> && key == other.key && value == other.value
+
+            override fun hashCode(): Int = key.hashCode() xor value.hashCode()
+
+            override fun toString(): String = "$key=$value"
+        }
+
+
+        assertTrue(map.keys.contains(key))
+
+        // This one requires special efforts to make it work this way.
+        // map.entries can in fact be `MutableSet<MutableMap.MutableEntry>`,
+        // which [contains] method takes [MutableEntry], so the compiler may generate special bridge
+        // returning false for values that aren't [MutableEntry] (including [SimpleEntry]).
+        assertTrue(map.entries.contains(SimpleEntry(key, value)))
+
+        assertTrue(map.entries.toSet().contains(SimpleEntry(key, value)))
+    }
+}