Generate enum entries classes with package private visibility

#KT-6574 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java

@@ -407,6 +407,9 @@ public class AsmUtil {
         if (ExpectedActualDeclarationChecker.isOptionalAnnotationClass(descriptor)) {
             return NO_FLAG_PACKAGE_PRIVATE;
         }
+        if (descriptor.getKind() == ClassKind.ENUM_ENTRY) {
+            return NO_FLAG_PACKAGE_PRIVATE;
+        }
         if (descriptor.getVisibility() == Visibilities.PUBLIC ||
             descriptor.getVisibility() == Visibilities.PROTECTED ||
             // TODO: should be package private, but for now Kotlin's reflection can't access members of such classes

compiler/testData/writeFlags/class/visibility/packageprivate/enumEntry.kt

@@ -0,0 +1,9 @@
+enum class Foo {
+    A {
+        fun foo() {}
+    }
+}
+
+// TESTED_OBJECT_KIND: class
+// TESTED_OBJECTS: Foo$A
+// FLAGS: ACC_FINAL, ACC_SUPER

compiler/tests/org/jetbrains/kotlin/codegen/flags/WriteFlagsTestGenerated.java

@@ -248,6 +248,24 @@ public class WriteFlagsTestGenerated extends AbstractWriteFlagsTest {
                 }
             }
 
+            @TestMetadata("compiler/testData/writeFlags/class/visibility/packageprivate")
+            @TestDataPath("$PROJECT_ROOT")
+            @RunWith(JUnit3RunnerWithInners.class)
+            public static class Packageprivate extends AbstractWriteFlagsTest {
+                private void runTest(String testDataFilePath) throws Exception {
+                    KotlinTestUtils.runTest(this::doTest, TargetBackend.ANY, testDataFilePath);
+                }
+
+                public void testAllFilesPresentInPackageprivate() throws Exception {
+                    KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/writeFlags/class/visibility/packageprivate"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
+                }
+
+                @TestMetadata("enumEntry.kt")
+                public void testEnumEntry() throws Exception {
+                    runTest("compiler/testData/writeFlags/class/visibility/packageprivate/enumEntry.kt");
+                }
+            }
+
             @TestMetadata("compiler/testData/writeFlags/class/visibility/private")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)