Fix for enum equals method (#1638)

* Fix for enum equals

backend.native/tests/build.gradle

@@ -516,6 +516,11 @@ task hello4(type: RunKonanTest) {
     source = "runtime/basic/hello4.kt"
 }
 
+task enumEquals(type: RunKonanTest) {
+    goldValue = "true\nfalse\nfalse\n"
+    source = "runtime/basic/enum_equals.kt"
+}
+
 task entry0(type: RunStandaloneKonanTest) {
     goldValue = "Hello.\n"
     source = "runtime/basic/entry0.kt"
@@ -658,6 +663,12 @@ task freeze_stress(type: RunKonanTest) {
     source = "runtime/workers/freeze_stress.kt"
 }
 
+task enumIdentity(type: RunKonanTest) {
+    disabled = (project.testTarget == 'wasm32') // Workers need pthreads.
+    goldValue = "true\n"
+    source = "runtime/workers/enum_identity.kt"
+}
+
 task superFunCall(type: RunKonanTest) {
     goldValue = "<fun:C><fun:C1>\n<fun:C><fun:C3>\n"
     source = "codegen/basics/superFunCall.kt"

backend.native/tests/runtime/basic/enum_equals.kt

@@ -0,0 +1,17 @@
+package runtime.basic.enum_equals
+
+import kotlin.test.*
+
+enum class EnumA {
+    A, B
+}
+
+enum class EnumB {
+    B
+}
+
+@Test fun run() {
+    println(EnumA.A == EnumA.A)
+    println(EnumA.A == EnumA.B)
+    println(EnumA.A == EnumB.B)
+}

backend.native/tests/runtime/workers/enum_identity.kt

@@ -0,0 +1,19 @@
+package runtime.workers.enum_identity
+
+import kotlin.test.*
+import konan.worker.*
+
+enum class A {
+    A, B
+}
+
+data class Foo(val kind: A)
+
+// Enums are shared between threads so identity should be kept.
+@Test
+fun runTest() {
+    val result = startWorker().schedule(TransferMode.CHECKED, { Foo(A.B) }, { input ->
+        input.kind == A.B
+    }).result()
+    println(result)
+}

runtime/src/main/kotlin/kotlin/Enum.kt

@@ -36,7 +36,7 @@ public abstract class Enum<E: Enum<E>>(public val name: String, public val ordin
     }
 
     public override final fun equals(other: Any?): Boolean {
-        return other is Enum<*> && ordinal == other.ordinal
+        return this === other
     }
 
     public override final fun hashCode(): Int {