KT-4107 Data objects

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -737,6 +737,7 @@ public interface Errors {
     DiagnosticFactory0<PsiElement> DATA_CLASS_WITHOUT_PARAMETERS = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtParameter> DATA_CLASS_VARARG_PARAMETER = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtParameter> DATA_CLASS_NOT_PROPERTY_PARAMETER = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory0<PsiElement> DATA_OBJECT_CUSTOM_EQUALS_OR_HASH_CODE = DiagnosticFactory0.create(ERROR);
 
     DiagnosticFactory0<KtParameter> CATCH_PARAMETER_WITH_DEFAULT_VALUE = DiagnosticFactory0.create(ERROR);
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -1058,6 +1058,7 @@ public class DefaultErrorMessages {
         MAP.put(DATA_CLASS_WITHOUT_PARAMETERS, "Data class must have at least one primary constructor parameter");
         MAP.put(DATA_CLASS_VARARG_PARAMETER, "Primary constructor vararg parameters are forbidden for data classes");
         MAP.put(DATA_CLASS_NOT_PROPERTY_PARAMETER, "Data class primary constructor must only have property (val / var) parameters");
+        MAP.put(DATA_OBJECT_CUSTOM_EQUALS_OR_HASH_CODE, "Data object cannot have a custom implementation of 'equals' or 'hashCode'");
 
         MAP.put(CATCH_PARAMETER_WITH_DEFAULT_VALUE, "Catch clause parameter may not have a default value");
 

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

@@ -52,6 +52,7 @@ private val DEFAULT_DECLARATION_CHECKERS = listOf(
     ValueParameterUsageInDefaultArgumentChecker,
     CyclicAnnotationsChecker,
     UnsupportedUntilRangeDeclarationChecker,
+    DataObjectContentChecker,
 )
 
 private val DEFAULT_CALL_CHECKERS = listOf(

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/DataClassDeclarationChecker.kt

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.resolve.checkers
 
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.diagnostics.Errors
 import org.jetbrains.kotlin.psi.KtClassOrObject
@@ -27,7 +28,7 @@ class DataClassDeclarationChecker : DeclarationChecker {
         if (descriptor !is ClassDescriptor) return
         if (declaration !is KtClassOrObject) return
 
-        if (descriptor.isData) {
+        if (descriptor.isData && descriptor.kind == ClassKind.CLASS) {
             if (descriptor.unsubstitutedPrimaryConstructor == null && descriptor.constructors.isNotEmpty()) {
                 declaration.nameIdentifier?.let { context.trace.report(Errors.PRIMARY_CONSTRUCTOR_REQUIRED_FOR_DATA_CLASS.on(it)) }
             }

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/DataObjectContentChecker.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.resolve.checkers
+
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.diagnostics.Errors
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.KtDeclaration
+import org.jetbrains.kotlin.resolve.DescriptorUtils
+import org.jetbrains.kotlin.util.OperatorNameConventions
+
+object DataObjectContentChecker : DeclarationChecker {
+    override fun check(declaration: KtDeclaration, descriptor: DeclarationDescriptor, context: DeclarationCheckerContext) {
+        if (descriptor !is FunctionDescriptor) return
+        if (descriptor.name != OperatorNameConventions.EQUALS && descriptor.name != OperatorNameConventions.HASH_CODE) return
+
+        val container = descriptor.containingDeclaration
+        if (container !is ClassDescriptor) return
+        if (!container.isData || container.kind != ClassKind.OBJECT) return
+
+        if (DescriptorUtils.getAllOverriddenDescriptors(descriptor).any(::isDeclaredInAny)) {
+            val target = declaration.modifierList?.getModifier(KtTokens.OVERRIDE_KEYWORD) ?: declaration
+            context.trace.report(Errors.DATA_OBJECT_CUSTOM_EQUALS_OR_HASH_CODE.on(target))
+        }
+    }
+
+    private fun isDeclaredInAny(descriptor: FunctionDescriptor): Boolean {
+        val container = descriptor.containingDeclaration
+        return container is ClassDescriptor && KotlinBuiltIns.isAny(container)
+    }
+}

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

@@ -482,7 +482,7 @@ open class LazyClassMemberScope(
     }
 
     private fun addDataClassMethods(result: MutableCollection<DeclarationDescriptor>, location: LookupLocation) {
-        if (!thisDescriptor.isData) return
+        if (!thisDescriptor.isData || thisDescriptor.kind != ClassKind.CLASS) return
 
         if (getPrimaryConstructor() == null) return