Allow default object to be denoted with 'default' modifier

Report 'default' modifier in illegal positions

compiler/frontend/src/org/jetbrains/kotlin/psi/JetObjectDeclaration.java

@@ -91,7 +91,7 @@ public class JetObjectDeclaration extends JetNamedDeclarationStub<KotlinObjectSt
         if (stub != null) {
             return stub.isDefault();
         }
-        return getClassKeyword() != null;
+        return getClassKeyword() != null || hasModifier(JetTokens.DEFAULT_KEYWORD);
     }
 
     @Override

compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.java

@@ -39,6 +39,7 @@ import java.util.*;
 
 import static org.jetbrains.kotlin.diagnostics.Errors.*;
 import static org.jetbrains.kotlin.lexer.JetTokens.*;
+import static org.jetbrains.kotlin.psi.JetStubbedPsiUtil.getContainingDeclaration;
 import static org.jetbrains.kotlin.resolve.DescriptorUtils.isDefaultObject;
 import static org.jetbrains.kotlin.resolve.DescriptorUtils.isEnumEntry;
 
@@ -141,6 +142,7 @@ public class ModifiersChecker {
         }
         else {
             checkInnerModifier(modifierListOwner, descriptor);
+            checkDefaultModifier(modifierListOwner);
             checkModalityModifiers(modifierListOwner);
             checkVisibilityModifiers(modifierListOwner, descriptor);
             checkVarianceModifiersOfTypeParameters(modifierListOwner);
@@ -232,6 +234,24 @@ public class ModifiersChecker {
         IN_OBJECT,
     }
 
+    private void checkDefaultModifier(@NotNull JetDeclaration declaration) {
+        if (declaration.hasModifier(DEFAULT_KEYWORD) && !isDefaultModifierAllowed(declaration)) {
+            reportIllegalModifiers(declaration, Collections.singletonList(DEFAULT_KEYWORD));
+        }
+    }
+
+    // NOTE: just checks if this is legal context for default modifier (Default object descriptor can be created)
+    // DEFAULT_OBJECT_NOT_ALLOWED can be reported later
+    public static boolean isDefaultModifierAllowed(@NotNull JetDeclaration declaration) {
+        if (declaration instanceof JetObjectDeclaration) {
+            JetDeclaration containingDeclaration = getContainingDeclaration(declaration);
+            if (containingDeclaration instanceof JetClassOrObject) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     @NotNull
     private static InnerModifierCheckResult checkIllegalInner(DeclarationDescriptor descriptor) {
         if (!(descriptor instanceof ClassDescriptor)) return InnerModifierCheckResult.ILLEGAL_POSITION;

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/data/JetClassOrObjectInfo.java

@@ -20,9 +20,9 @@ import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.kotlin.name.FqName;
 import org.jetbrains.kotlin.name.Name;
 import org.jetbrains.kotlin.psi.*;
-import org.jetbrains.kotlin.name.FqName;
 
 import java.util.Collections;
 import java.util.List;

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/data/JetObjectInfo.java

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.descriptors.ClassKind;
 import org.jetbrains.kotlin.psi.JetObjectDeclaration;
 import org.jetbrains.kotlin.psi.JetParameter;
 import org.jetbrains.kotlin.psi.JetTypeParameterList;
+import org.jetbrains.kotlin.resolve.ModifiersChecker;
 
 import java.util.Collections;
 import java.util.List;
@@ -54,6 +55,6 @@ public class JetObjectInfo extends JetClassOrObjectInfo<JetObjectDeclaration> {
     }
 
     public boolean isDefaultObject() {
-        return element.isDefault();
+        return element.isDefault() && ModifiersChecker.isDefaultModifierAllowed(element);
     }
 }

compiler/testData/diagnostics/tests/classObjects/multipleDissallowedDefaultObjects.kt

@@ -0,0 +1,17 @@
+class A {
+    inner class I {
+        default <!DEFAULT_OBJECT_NOT_ALLOWED!>object A<!>
+
+        default <!MANY_DEFAULT_OBJECTS, MANY_DEFAULT_OBJECTS, DEFAULT_OBJECT_NOT_ALLOWED!>object B<!>
+
+        default <!MANY_DEFAULT_OBJECTS, MANY_DEFAULT_OBJECTS, DEFAULT_OBJECT_NOT_ALLOWED!>object C<!>
+    }
+}
+
+object O {
+    default <!DEFAULT_OBJECT_NOT_ALLOWED!>object A<!>
+
+    default <!MANY_DEFAULT_OBJECTS, DEFAULT_OBJECT_NOT_ALLOWED!>object B<!>
+
+    default <!MANY_DEFAULT_OBJECTS, DEFAULT_OBJECT_NOT_ALLOWED!>object C<!>
+}

compiler/testData/diagnostics/tests/classObjects/multipleDissallowedDefaultObjects.txt

@@ -0,0 +1,64 @@
+package
+
+internal final 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 final inner class I {
+        public constructor I()
+        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 A {
+            private 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 B {
+            private constructor B()
+            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 C {
+            private constructor C()
+            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 O {
+    private constructor O()
+    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 A {
+        private 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 B {
+        private constructor B()
+        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 C {
+        private constructor C()
+        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/testData/diagnostics/tests/modifiers/defaultModifier.kt

@@ -0,0 +1,55 @@
+<!ILLEGAL_MODIFIER!>default<!> class A {
+    default object {
+
+    }
+}
+
+class B {
+    default object
+
+    val c: Int = 1
+}
+
+class C {
+    default object A {
+
+    }
+}
+
+class D {
+    default object A {
+        default <!DEFAULT_OBJECT_NOT_ALLOWED!>object<!> {
+        }
+    }
+}
+
+<!ILLEGAL_MODIFIER!>default<!> object G {
+    default <!DEFAULT_OBJECT_NOT_ALLOWED!>object<!>
+}
+
+<!ILLEGAL_MODIFIER!>default<!> trait H {
+    default object
+}
+
+class J {
+    default object C {
+        default <!DEFAULT_OBJECT_NOT_ALLOWED!>object<!>
+    }
+}
+
+<!ILLEGAL_MODIFIER!>default<!> enum class Enum {
+    E1
+    E2
+
+    default object
+}
+
+<!ILLEGAL_MODIFIER!>default<!> fun main() {
+
+}
+
+<!ILLEGAL_MODIFIER!>default<!> var prop: Int = 1
+    <!ILLEGAL_MODIFIER!>default<!> get
+    <!ILLEGAL_MODIFIER!>default<!> set
+
+class Z(<!ILLEGAL_MODIFIER!>default<!> val c: Int)

compiler/testData/diagnostics/tests/modifiers/defaultModifier.txt

@@ -0,0 +1,165 @@
+package
+
+internal var prop: kotlin.Int
+internal fun main(): kotlin.Unit
+
+internal final 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 Default {
+        private constructor Default()
+        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 final class B {
+    public constructor B()
+    internal final val c: kotlin.Int = 1
+    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 Default {
+        private constructor Default()
+        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 final class C {
+    public constructor C()
+    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 A {
+        private 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 final class D {
+    public constructor 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 class object A {
+        private 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 Default {
+            private constructor Default()
+            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 final enum class Enum : kotlin.Enum<Enum> {
+    public enum entry E1 : Enum {
+        private constructor E1()
+        public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: Enum): 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
+    }
+
+    public enum entry E2 : Enum {
+        private constructor E2()
+        public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: Enum): 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 Enum()
+    public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: Enum): 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
+
+    internal class object Default {
+        private constructor Default()
+        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
+    }
+
+    // Static members
+    public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): Enum
+    public final /*synthesized*/ fun values(): kotlin.Array<Enum>
+}
+
+internal object G {
+    private constructor G()
+    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 Default {
+        private constructor Default()
+        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 trait H {
+    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 Default {
+        private constructor Default()
+        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 final class J {
+    public constructor J()
+    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 C {
+        private constructor C()
+        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 Default {
+            private constructor Default()
+            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 final class Z {
+    public constructor Z(/*0*/ c: kotlin.Int)
+    internal final val c: kotlin.Int
+    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/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -1576,6 +1576,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("multipleDissallowedDefaultObjects.kt")
+            public void testMultipleDissallowedDefaultObjects() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/classObjects/multipleDissallowedDefaultObjects.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("nestedClassInPrivateClassObject.kt")
             public void testNestedClassInPrivateClassObject() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/classObjects/nestedClassInPrivateClassObject.kt");
@@ -7380,6 +7386,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/modifiers"), Pattern.compile("^(.+)\\.kt$"), true);
             }
 
+            @TestMetadata("defaultModifier.kt")
+            public void testDefaultModifier() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/modifiers/defaultModifier.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("IllegalModifiers.kt")
             public void testIllegalModifiers() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/modifiers/IllegalModifiers.kt");