KT-12358: fake override of a method of 'Any' in an interface is not an "implementation".

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

@@ -32,6 +32,7 @@ import kotlin.jvm.functions.Function1;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.annotations.ReadOnly;
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.diagnostics.DiagnosticFactory2;
 import org.jetbrains.kotlin.diagnostics.DiagnosticFactoryWithPsiElement;
@@ -618,13 +619,40 @@ public class OverrideResolver {
     private static List<CallableMemberDescriptor> collectImplementations(@NotNull Set<CallableMemberDescriptor> relevantDirectlyOverridden) {
         List<CallableMemberDescriptor> result = new ArrayList<CallableMemberDescriptor>(relevantDirectlyOverridden.size());
         for (CallableMemberDescriptor overriddenDescriptor : relevantDirectlyOverridden) {
-            if (overriddenDescriptor.getModality() != Modality.ABSTRACT) {
+            if (isImplementation(overriddenDescriptor)) {
                 result.add(overriddenDescriptor);
             }
         }
         return result;
     }
 
+    private static boolean isImplementation(@NotNull CallableMemberDescriptor callableMemberDescriptor) {
+        // An abstract member is not an implementation.
+        if (callableMemberDescriptor.getModality() == Modality.ABSTRACT) return false;
+
+        // Interfaces contain fake overrides for 'toString', 'hashCode', 'equals'.
+        // They are not considered implementations if their dispatch receiver type is 'Any'.
+        DeclarationDescriptor containingDeclaration = callableMemberDescriptor.getContainingDeclaration();
+        assert containingDeclaration instanceof ClassDescriptor :
+                "ClassDescriptor expected, got " + containingDeclaration + " for " + callableMemberDescriptor;
+        ClassDescriptor containingClassDescriptor = (ClassDescriptor) containingDeclaration;
+        if (containingClassDescriptor.getKind() == ClassKind.INTERFACE && callableMemberDescriptor.getKind() == FAKE_OVERRIDE) {
+            ReceiverParameterDescriptor dispatchReceiverParameter = callableMemberDescriptor.getDispatchReceiverParameter();
+            if (dispatchReceiverParameter == null) return false;
+            if (KotlinBuiltIns.isAny(dispatchReceiverParameter.getType())) return false;
+        }
+
+        // A FAKE_OVERRIDE is an implementation iff it overrides an implementation.
+        if (callableMemberDescriptor.getKind() == FAKE_OVERRIDE) {
+            for (CallableMemberDescriptor overriddenDescriptor : callableMemberDescriptor.getOverriddenDescriptors()) {
+                if (isImplementation(overriddenDescriptor)) return true;
+            }
+            return false;
+        }
+
+        return true;
+    }
+
     private static void filterNotSynthesizedDescriptorsByModality(
             @NotNull Set<CallableMemberDescriptor> allOverriddenDeclarations,
             @NotNull List<CallableMemberDescriptor> abstractOverridden,

compiler/testData/diagnostics/tests/override/kt12358.kt

@@ -0,0 +1,9 @@
+abstract class A {
+    abstract override fun toString(): String
+}
+
+interface B
+
+abstract class C : A(), B
+
+<!ABSTRACT_MEMBER_NOT_IMPLEMENTED!>class Test<!> : C()

compiler/testData/diagnostics/tests/override/kt12358.txt

@@ -0,0 +1,28 @@
+package
+
+public abstract 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 abstract override /*1*/ fun toString(): kotlin.String
+}
+
+public interface 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
+}
+
+public abstract class C : A, B {
+    public constructor C()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Test : C {
+    public constructor Test()
+    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/DiagnosticsTestGenerated.java

@@ -12216,6 +12216,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("kt12358.kt")
+            public void testKt12358() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/override/kt12358.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("kt1862.kt")
             public void testKt1862() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/override/kt1862.kt");