Allow data classes to implement equals/hashCode/toString from base classes

#KT-11306 Fixed

compiler/backend-common/src/org/jetbrains/kotlin/backend/common/DataClassMethodGenerator.kt

@@ -112,8 +112,7 @@ abstract class DataClassMethodGenerator(private val declaration: KtClassOrObject
     ): FunctionDescriptor? =
             classDescriptor.unsubstitutedMemberScope.getContributedFunctions(Name.identifier(name), NoLookupLocation.FROM_BACKEND)
                     .singleOrNull { function ->
-                        !function.kind.isReal &&
-                        function.modality != Modality.FINAL &&
+                        function.kind == CallableMemberDescriptor.Kind.SYNTHESIZED &&
                         areParametersOk(function.valueParameters) &&
                         function.returnType != null &&
                         isReturnTypeOk(function.returnType!!)

compiler/frontend/src/org/jetbrains/kotlin/resolve/DataClassDescriptorResolver.kt

@@ -20,9 +20,16 @@ import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.descriptors.impl.SimpleFunctionDescriptorImpl
 import org.jetbrains.kotlin.descriptors.impl.ValueParameterDescriptorImpl
+import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.resolve.descriptorUtil.builtIns
+import org.jetbrains.kotlin.util.OperatorNameConventions
 
 object DataClassDescriptorResolver {
+    val EQUALS_METHOD_NAME = OperatorNameConventions.EQUALS
+    val HASH_CODE_METHOD_NAME = Name.identifier("hashCode")
+    val TO_STRING_METHOD_NAME = Name.identifier("toString")
+
     val COPY_METHOD_NAME = Name.identifier("copy")
 
     private val COMPONENT_FUNCTION_NAME_PREFIX = "component"
@@ -49,6 +56,36 @@ object DataClassDescriptorResolver {
         return true
     }
 
+    fun createEqualsFunctionDescriptor(classDescriptor: ClassDescriptor): SimpleFunctionDescriptor =
+            doCreateFunctionFromAny(classDescriptor, EQUALS_METHOD_NAME)
+
+    fun createHashCodeFunctionDescriptor(classDescriptor: ClassDescriptor): SimpleFunctionDescriptor =
+            doCreateFunctionFromAny(classDescriptor, HASH_CODE_METHOD_NAME)
+
+    fun createToStringFunctionDescriptor(classDescriptor: ClassDescriptor): SimpleFunctionDescriptor =
+            doCreateFunctionFromAny(classDescriptor, TO_STRING_METHOD_NAME)
+
+    private fun doCreateFunctionFromAny(classDescriptor: ClassDescriptor, name: Name): SimpleFunctionDescriptor {
+        val functionDescriptor = SimpleFunctionDescriptorImpl.create(
+                classDescriptor, Annotations.EMPTY, name, CallableMemberDescriptor.Kind.SYNTHESIZED, classDescriptor.source
+        )
+
+        val functionFromAny = classDescriptor.builtIns.any.getMemberScope(emptyList())
+                .getContributedFunctions(name, NoLookupLocation.FROM_BUILTINS).single()
+
+        functionDescriptor.initialize(
+                null,
+                classDescriptor.thisAsReceiverParameter,
+                functionFromAny.typeParameters,
+                functionFromAny.valueParameters.map { it.copy(functionDescriptor, it.name, it.index) },
+                functionFromAny.returnType,
+                Modality.OPEN,
+                Visibilities.PUBLIC
+        )
+
+        return functionDescriptor
+    }
+
     fun createComponentFunctionDescriptor(
             parameterIndex: Int,
             property: PropertyDescriptor,

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassMemberScope.kt

@@ -16,7 +16,7 @@
 
 package org.jetbrains.kotlin.resolve.lazy.descriptors
 
-import com.google.common.collect.Lists
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.DELEGATION
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.FAKE_OVERRIDE
@@ -129,16 +129,21 @@ open class LazyClassMemberScope(
     override fun getNonDeclaredFunctions(name: Name, result: MutableSet<SimpleFunctionDescriptor>) {
         val location = NoLookupLocation.FOR_ALREADY_TRACKED
 
-        val fromSupertypes = Lists.newArrayList<SimpleFunctionDescriptor>()
+        val fromSupertypes = arrayListOf<SimpleFunctionDescriptor>()
         for (supertype in thisDescriptor.typeConstructor.supertypes) {
             fromSupertypes.addAll(supertype.memberScope.getContributedFunctions(name, location))
         }
         result.addAll(generateDelegatingDescriptors(name, EXTRACT_FUNCTIONS, result))
-        generateDataClassMethods(result, name, location)
+        generateDataClassMethods(result, name, location, fromSupertypes)
         generateFakeOverrides(name, fromSupertypes, result, SimpleFunctionDescriptor::class.java)
     }
 
-    private fun generateDataClassMethods(result: MutableCollection<SimpleFunctionDescriptor>, name: Name, location: LookupLocation) {
+    private fun generateDataClassMethods(
+            result: MutableCollection<SimpleFunctionDescriptor>,
+            name: Name,
+            location: LookupLocation,
+            fromSupertypes: List<SimpleFunctionDescriptor>
+    ) {
         if (!thisDescriptor.isData) return
 
         val constructor = getPrimaryConstructor() ?: return
@@ -177,6 +182,27 @@ open class LazyClassMemberScope(
 
             result.add(DataClassDescriptorResolver.createCopyFunctionDescriptor(constructor.valueParameters, thisDescriptor, trace))
         }
+
+        fun shouldAddFunctionFromAny(checkParameters: (FunctionDescriptor) -> Boolean): Boolean {
+            // Add 'equals', 'hashCode', 'toString' iff there is no such declared member AND there is no such final member in supertypes
+            return result.none(checkParameters) &&
+                   fromSupertypes.none { checkParameters(it) && it.modality == Modality.FINAL }
+        }
+
+        if (name == DataClassDescriptorResolver.EQUALS_METHOD_NAME && shouldAddFunctionFromAny { function ->
+            val parameters = function.valueParameters
+            parameters.size == 1 && KotlinBuiltIns.isNullableAny(parameters.first().type)
+        }) {
+            result.add(DataClassDescriptorResolver.createEqualsFunctionDescriptor(thisDescriptor))
+        }
+
+        if (name == DataClassDescriptorResolver.HASH_CODE_METHOD_NAME && shouldAddFunctionFromAny { it.valueParameters.isEmpty() }) {
+            result.add(DataClassDescriptorResolver.createHashCodeFunctionDescriptor(thisDescriptor))
+        }
+
+        if (name == DataClassDescriptorResolver.TO_STRING_METHOD_NAME && shouldAddFunctionFromAny { it.valueParameters.isEmpty() }) {
+            result.add(DataClassDescriptorResolver.createToStringFunctionDescriptor(thisDescriptor))
+        }
     }
 
     override fun getContributedVariables(name: Name, location: LookupLocation): Collection<PropertyDescriptor> {

compiler/testData/diagnostics/tests/dataClasses/finalMembersInBaseClass.kt

@@ -0,0 +1,16 @@
+abstract class Base {
+    final override fun equals(other: Any?) = false
+    final override fun hashCode() = 42
+
+    open override fun toString() = "OK"
+}
+
+data class Data1(val field: String) : Base()
+
+interface AbstractAnyMembers {
+    abstract override fun equals(other: Any?): Boolean
+    abstract override fun hashCode(): Int
+    abstract override fun toString(): String
+}
+
+data class Data2(val field: String): Base(), AbstractAnyMembers

compiler/testData/diagnostics/tests/dataClasses/finalMembersInBaseClass.txt

@@ -0,0 +1,34 @@
+package
+
+public interface AbstractAnyMembers {
+    public abstract override /*1*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*1*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ fun toString(): kotlin.String
+}
+
+public abstract class Base {
+    public constructor Base()
+    public final override /*1*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final override /*1*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun toString(): kotlin.String
+}
+
+public final data class Data1 : Base {
+    public constructor Data1(/*0*/ field: kotlin.String)
+    public final val field: kotlin.String
+    public final operator /*synthesized*/ fun component1(): kotlin.String
+    public final /*synthesized*/ fun copy(/*0*/ field: kotlin.String = ...): Data1
+    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 open override /*1*/ /*synthesized*/ fun toString(): kotlin.String
+}
+
+public final data class Data2 : Base, AbstractAnyMembers {
+    public constructor Data2(/*0*/ field: kotlin.String)
+    public final val field: kotlin.String
+    public final operator /*synthesized*/ fun component1(): kotlin.String
+    public final /*synthesized*/ fun copy(/*0*/ field: kotlin.String = ...): Data2
+    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 open override /*2*/ /*synthesized*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/dataClasses/implementMethodsFromInterface.kt

@@ -0,0 +1,25 @@
+// KT-11306 ABSTRACT_MEMBER_NOT_IMPLEMENTED for data class should inheriting interfaces requiring equals(), hashCode(), or toString()
+
+interface Foo {
+    override fun equals(other: Any?): Boolean
+    override fun hashCode(): Int
+    override fun toString(): String
+}
+
+data class FooImpl(val num: Int) : Foo
+
+data class FooImplSome(val num: Int) : Foo {
+    override fun hashCode() = 42
+}
+
+data class FooImplAll(val num: Int) : Foo {
+    override fun equals(other: Any?) = false
+    override fun hashCode() = 42
+    override fun toString() = "OK"
+}
+
+
+data class WrongSignatures(val num: Int) : Foo {
+    <!NOTHING_TO_OVERRIDE!>override<!> fun equals(other: WrongSignatures) = false
+    override fun hashCode(): <!RETURN_TYPE_MISMATCH_ON_OVERRIDE!>Boolean<!> = true
+}

compiler/testData/diagnostics/tests/dataClasses/implementMethodsFromInterface.txt

@@ -0,0 +1,48 @@
+package
+
+public interface Foo {
+    public abstract override /*1*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*1*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ fun toString(): kotlin.String
+}
+
+public final data class FooImpl : Foo {
+    public constructor FooImpl(/*0*/ num: kotlin.Int)
+    public final val num: kotlin.Int
+    public final operator /*synthesized*/ fun component1(): kotlin.Int
+    public final /*synthesized*/ fun copy(/*0*/ num: kotlin.Int = ...): FooImpl
+    public open override /*1*/ /*synthesized*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*synthesized*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*synthesized*/ fun toString(): kotlin.String
+}
+
+public final data class FooImplAll : Foo {
+    public constructor FooImplAll(/*0*/ num: kotlin.Int)
+    public final val num: kotlin.Int
+    public final operator /*synthesized*/ fun component1(): kotlin.Int
+    public final /*synthesized*/ fun copy(/*0*/ num: kotlin.Int = ...): FooImplAll
+    public open override /*1*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun toString(): kotlin.String
+}
+
+public final data class FooImplSome : Foo {
+    public constructor FooImplSome(/*0*/ num: kotlin.Int)
+    public final val num: kotlin.Int
+    public final operator /*synthesized*/ fun component1(): kotlin.Int
+    public final /*synthesized*/ fun copy(/*0*/ num: kotlin.Int = ...): FooImplSome
+    public open override /*1*/ /*synthesized*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*synthesized*/ fun toString(): kotlin.String
+}
+
+public final data class WrongSignatures : Foo {
+    public constructor WrongSignatures(/*0*/ num: kotlin.Int)
+    public final val num: kotlin.Int
+    public final operator /*synthesized*/ fun component1(): kotlin.Int
+    public final /*synthesized*/ fun copy(/*0*/ num: kotlin.Int = ...): WrongSignatures
+    public open fun equals(/*0*/ other: WrongSignatures): kotlin.Boolean
+    public open override /*1*/ /*synthesized*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun hashCode(): kotlin.Boolean
+    public open override /*1*/ /*synthesized*/ fun toString(): kotlin.String
+}

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

@@ -4320,6 +4320,18 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("finalMembersInBaseClass.kt")
+            public void testFinalMembersInBaseClass() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/dataClasses/finalMembersInBaseClass.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("implementMethodsFromInterface.kt")
+            public void testImplementMethodsFromInterface() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/dataClasses/implementMethodsFromInterface.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("implementTraitWhichHasComponent1.kt")
             public void testImplementTraitWhichHasComponent1() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/dataClasses/implementTraitWhichHasComponent1.kt");

idea/testData/structureView/fileStructure/InheritedSynthesizedFromDataClass.after

@@ -1,9 +1,6 @@
 -InheritedSynthesizedFromDataClass.kt
  -Derived
   a: Int location=→TestData
-  equals(Any?): Boolean location=→Any
   field: Int
-  hashCode(): Int location=→Any
   some(): Unit location=→TestData
-  toString(): String location=→Any
  TestData

jps-plugin/testData/comparison/classSignatureChange/classFlagsChanged/result.out

@@ -5,9 +5,9 @@ changes in test/AnnotationFlagAdded: CLASS_SIGNATURE
 changes in test/AnnotationFlagRemoved: CLASS_SIGNATURE
 changes in test/AnnotationFlagUnchanged: NONE
 changes in test/DataFlagAdded: CLASS_SIGNATURE, MEMBERS
-    [component1, copy]
+    [component1, copy, equals, hashCode, toString]
 changes in test/DataFlagRemoved: CLASS_SIGNATURE, MEMBERS
-    [component1, copy]
+    [component1, copy, equals, hashCode, toString]
 changes in test/DataFlagUnchanged: NONE
 changes in test/EnumFlagAdded: CLASS_SIGNATURE
 changes in test/EnumFlagRemoved: CLASS_SIGNATURE