Prohibit 'override' on classes and all modality on objects

#KT-3464 Fixed

compiler/frontend/src/org/jetbrains/jet/lang/resolve/ModifiersChecker.java

@@ -85,7 +85,7 @@ public class ModifiersChecker {
         }
         else {
             checkInnerModifier(modifierListOwner, descriptor);
-            checkModalityModifiers(modifierListOwner.getModifierList());
+            checkModalityModifiers(modifierListOwner);
             checkVisibilityModifiers(modifierListOwner, descriptor);
         }
         checkPlatformNameApplicability(descriptor);
@@ -107,12 +107,21 @@ public class ModifiersChecker {
         checkIllegalInThisContextModifiers(modifierListOwner, VISIBILITY_MODIFIERS);
     }
 
-    private void checkModalityModifiers(@Nullable JetModifierList modifierList) {
+    private void checkModalityModifiers(@NotNull JetModifierListOwner modifierListOwner) {
+        JetModifierList modifierList = modifierListOwner.getModifierList();
         if (modifierList == null) return;
+
         checkRedundantModifier(modifierList, Pair.create(OPEN_KEYWORD, ABSTRACT_KEYWORD), Pair.create(OPEN_KEYWORD, OVERRIDE_KEYWORD));
 
-        checkCompatibility(modifierList, Lists.newArrayList(ABSTRACT_KEYWORD, OPEN_KEYWORD, FINAL_KEYWORD),
+        checkCompatibility(modifierList, Arrays.asList(ABSTRACT_KEYWORD, OPEN_KEYWORD, FINAL_KEYWORD),
-                           Lists.newArrayList(ABSTRACT_KEYWORD, OPEN_KEYWORD));
+                           Arrays.asList(ABSTRACT_KEYWORD, OPEN_KEYWORD));
+
+        if (modifierListOwner.getParent() instanceof JetClassObject || modifierListOwner instanceof JetObjectDeclaration) {
+            checkIllegalModalityModifiers(modifierListOwner);
+        }
+        else if (modifierListOwner instanceof JetClassOrObject) {
+            checkIllegalInThisContextModifiers(modifierListOwner, Collections.singletonList(OVERRIDE_KEYWORD));
+        }
     }
 
     private void checkVisibilityModifiers(@NotNull JetModifierListOwner modifierListOwner, @NotNull DeclarationDescriptor descriptor) {

compiler/testData/diagnostics/tests/declarationChecks/illegalModifiersOnClass.kt

@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -MANY_CLASS_OBJECTS
+
+// KT-3464 Front-end shouldn't allow override modifier in class declaration
+
+<!ILLEGAL_MODIFIER!>override<!> class A {
+    <!ILLEGAL_MODIFIER!>override<!> class object {}
+    <!ILLEGAL_MODIFIER!>open<!> class object {}
+    <!ILLEGAL_MODIFIER!>abstract<!> class object {}
+    <!ILLEGAL_MODIFIER!>final<!> class object {}
+}
+
+<!ILLEGAL_MODIFIER!>override<!> object B1 {}
+<!ILLEGAL_MODIFIER!>open<!> object B2 {}
+<!ILLEGAL_MODIFIER!>abstract<!> object B3 {}
+<!ILLEGAL_MODIFIER!>final<!> object B4 {}
+
+<!ILLEGAL_MODIFIER!>override<!> enum class C {}
+<!ILLEGAL_MODIFIER!>override<!> trait D {}
+<!ILLEGAL_MODIFIER!>override<!> annotation class E

compiler/testData/diagnostics/tests/declarationChecks/illegalModifiersOnClass.txt

@@ -0,0 +1,98 @@
+package 
+
+internal open class A {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    
+    internal class object <class-object-for-A> {
+        private constructor <class-object-for-A>()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}
+
+internal object B1 {
+    private constructor B1()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    
+    public class object <class-object-for-B1> : B1 {
+        private constructor <class-object-for-B1>()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}
+
+internal object B2 {
+    private constructor B2()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    
+    public class object <class-object-for-B2> : B2 {
+        private constructor <class-object-for-B2>()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}
+
+internal object B3 {
+    private constructor B3()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    
+    public class object <class-object-for-B3> : B3 {
+        private constructor <class-object-for-B3>()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}
+
+internal object B4 {
+    private constructor B4()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    
+    public class object <class-object-for-B4> : B4 {
+        private constructor <class-object-for-B4>()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}
+
+internal open enum class C : kotlin.Enum<C> {
+    private constructor C()
+    public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: C): 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
+    
+    // Static members
+    public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): C
+    public final /*synthesized*/ fun values(): kotlin.Array<C>
+}
+
+internal trait D {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+internal open annotation class E : kotlin.Annotation {
+    public constructor E()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

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

@@ -2678,6 +2678,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
             
+            @TestMetadata("illegalModifiersOnClass.kt")
+            public void testIllegalModifiersOnClass() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/declarationChecks/illegalModifiersOnClass.kt");
+                doTest(fileName);
+            }
+            
             @TestMetadata("kt1141.kt")
             public void testKt1141() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/declarationChecks/kt1141.kt");