Prohibit clone() for enum classes

#KT-8972 Fixed

compiler/testData/builtin-classes.txt

@@ -417,6 +417,7 @@ public final class DoubleRange : kotlin.Range<kotlin.Double>, kotlin.Progression
 
 public abstract class Enum</*0*/ E : kotlin.Enum<E>> : kotlin.Comparable<E> {
     /*primary*/ public constructor Enum</*0*/ E : kotlin.Enum<E>>(/*0*/ name: kotlin.String, /*1*/ ordinal: kotlin.Int)
+    protected final fun clone(): kotlin.Any
     public final override /*1*/ fun compareTo(/*0*/ other: E): kotlin.Int
     public final fun name(): kotlin.String
     public final fun ordinal(): kotlin.Int
@@ -577,6 +578,7 @@ public interface Function</*0*/ out R> {
 public final enum class InlineOption : kotlin.Enum<kotlin.InlineOption> {
     public enum entry LOCAL_CONTINUE_AND_BREAK : kotlin.InlineOption {
         /*primary*/ private constructor LOCAL_CONTINUE_AND_BREAK()
+        protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
         public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: kotlin.InlineOption): kotlin.Int
         public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
         public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
@@ -584,12 +586,14 @@ public final enum class InlineOption : kotlin.Enum<kotlin.InlineOption> {
 
     public enum entry ONLY_LOCAL_RETURN : kotlin.InlineOption {
         /*primary*/ private constructor ONLY_LOCAL_RETURN()
+        protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
         public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: kotlin.InlineOption): kotlin.Int
         public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
         public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
     }
 
     /*primary*/ private constructor InlineOption()
+    protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
     public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: kotlin.InlineOption): kotlin.Int
     public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
     public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
@@ -602,6 +606,7 @@ public final enum class InlineOption : kotlin.Enum<kotlin.InlineOption> {
 public final enum class InlineStrategy : kotlin.Enum<kotlin.InlineStrategy> {
     public enum entry AS_FUNCTION : kotlin.InlineStrategy {
         /*primary*/ private constructor AS_FUNCTION()
+        protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
         public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: kotlin.InlineStrategy): kotlin.Int
         public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
         public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
@@ -609,12 +614,14 @@ public final enum class InlineStrategy : kotlin.Enum<kotlin.InlineStrategy> {
 
     public enum entry IN_PLACE : kotlin.InlineStrategy {
         /*primary*/ private constructor IN_PLACE()
+        protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
         public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: kotlin.InlineStrategy): kotlin.Int
         public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
         public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
     }
 
     /*primary*/ private constructor InlineStrategy()
+    protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
     public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: kotlin.InlineStrategy): kotlin.Int
     public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
     public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int

compiler/testData/diagnostics/tests/enum/kt8972_cloneNotAllowed.kt

@@ -0,0 +1,6 @@
+enum class E : Cloneable {
+    A;
+    <!OVERRIDING_FINAL_MEMBER!>override<!> fun clone(): Any {
+        return <!AMBIGUOUS_SUPER!>super<!>.<!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>clone<!>()
+    }
+}

compiler/testData/diagnostics/tests/enum/kt8972_cloneNotAllowed.txt

@@ -0,0 +1,27 @@
+package
+
+internal final enum class E : kotlin.Enum<E>, kotlin.Cloneable {
+    public enum entry A : E {
+        private constructor A()
+        protected open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+        public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: E): kotlin.Int
+        public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
+        public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+
+    private constructor E()
+    protected open override /*2*/ fun clone(): kotlin.Any
+    public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: E): kotlin.Int
+    public final override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
+    public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): E
+    public final /*synthesized*/ fun values(): kotlin.Array<E>
+}

compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -5298,6 +5298,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("kt8972_cloneNotAllowed.kt")
+            public void testKt8972_cloneNotAllowed() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/enum/kt8972_cloneNotAllowed.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("localEnums.kt")
             public void testLocalEnums() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/enum/localEnums.kt");

core/builtins/native/kotlin/Enum.kt

@@ -37,6 +37,12 @@ public abstract class Enum<E : Enum<E>>(name: String, ordinal: Int): Comparable<
 
     public override final fun compareTo(other: E): Int
 
+    /**
+     * Throws an exception since enum constants cannot be cloned.
+     * This method prevents enum classes from inheriting from [Cloneable].
+     */
+    protected final fun clone(): Any
+
     public override final fun equals(other: Any?): Boolean
     public override final fun hashCode(): Int
     public override fun toString(): String

idea/testData/structureView/fileStructure/InheritedMembersOfEnum.after

@@ -1,5 +1,6 @@
 -InheritedMembersOfEnum.kt
  -Test
+  clone(): Any location=→Enum
   compareTo(E): Int location=→Enum
   equals(Any?): Boolean location=→Enum
   FIRST