Prohibit return type mismatch for delegation members

#KT-13952 Fixed
 #KT-13005 Fixed

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

@@ -363,6 +363,10 @@ public interface Errors {
             DiagnosticFactory2.create(ERROR, DECLARATION_NAME);
     DiagnosticFactory2<KtClassOrObject, CallableMemberDescriptor, CallableMemberDescriptor> VAR_OVERRIDDEN_BY_VAL_BY_DELEGATION =
             DiagnosticFactory2.create(ERROR, DECLARATION_NAME);
+    DiagnosticFactory2<KtClassOrObject, CallableMemberDescriptor, CallableMemberDescriptor> RETURN_TYPE_MISMATCH_BY_DELEGATION =
+            DiagnosticFactory2.create(ERROR, DECLARATION_NAME);
+    DiagnosticFactory2<KtClassOrObject, CallableMemberDescriptor, CallableMemberDescriptor> PROPERTY_TYPE_MISMATCH_BY_DELEGATION =
+            DiagnosticFactory2.create(ERROR, DECLARATION_NAME);
 
     DiagnosticFactory2<KtClassOrObject, ClassDescriptor, Collection<CallableMemberDescriptor>> CONFLICTING_INHERITED_MEMBERS =
             DiagnosticFactory2.create(ERROR, DECLARATION_NAME);

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

@@ -613,6 +613,10 @@ public class DefaultErrorMessages {
                 SHORT_NAMES_IN_TYPES, SHORT_NAMES_IN_TYPES);
         MAP.put(VAR_OVERRIDDEN_BY_VAL_BY_DELEGATION, "Val-property ''{0}'' implicitly overrides a var-property ''{1}'' by delegation",
                 SHORT_NAMES_IN_TYPES, SHORT_NAMES_IN_TYPES);
+        MAP.put(RETURN_TYPE_MISMATCH_BY_DELEGATION, "Type of ''{0}'' is not a subtype of overridden by delegation ''{1}''",
+                SHORT_NAMES_IN_TYPES, SHORT_NAMES_IN_TYPES);
+        MAP.put(PROPERTY_TYPE_MISMATCH_BY_DELEGATION, "Type of property ''{0}'' is not a subtype of overridden by delegation ''{1}''",
+                SHORT_NAMES_IN_TYPES, SHORT_NAMES_IN_TYPES);
 
         MAP.put(VAR_OVERRIDDEN_BY_VAL, "Var-property {0} cannot be overridden by val-property {1}", FQ_NAMES_IN_TYPES, FQ_NAMES_IN_TYPES);
 

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

@@ -240,7 +240,7 @@ public class OverrideResolver {
 
         @Override
         public void overridingFinalMember(@NotNull CallableMemberDescriptor overriding, @NotNull CallableMemberDescriptor overridden) {
-            reportDelegationProblemIfRequired(OVERRIDING_FINAL_MEMBER_BY_DELEGATION, overriding, overridden);
+            reportDelegationProblemIfRequired(OVERRIDING_FINAL_MEMBER_BY_DELEGATION, null, overriding, overridden);
         }
 
         @Override
@@ -248,7 +248,8 @@ public class OverrideResolver {
                 @NotNull CallableMemberDescriptor overriding,
                 @NotNull CallableMemberDescriptor overridden
         ) {
-            // Always reported as RETURN_TYPE_MISMATCH_ON_INHERITANCE
+            reportDelegationProblemIfRequired(
+                    RETURN_TYPE_MISMATCH_BY_DELEGATION, RETURN_TYPE_MISMATCH_ON_INHERITANCE, overriding, overridden);
         }
 
         @Override
@@ -256,22 +257,25 @@ public class OverrideResolver {
                 @NotNull PropertyDescriptor overriding,
                 @NotNull PropertyDescriptor overridden
         ) {
-            // Always reported as PROPERTY_TYPE_MISMATCH_ON_INHERITANCE
+            reportDelegationProblemIfRequired(
+                    PROPERTY_TYPE_MISMATCH_BY_DELEGATION, PROPERTY_TYPE_MISMATCH_ON_INHERITANCE, overriding, overridden);
         }
 
         @Override
         public void varOverriddenByVal(@NotNull CallableMemberDescriptor overriding, @NotNull CallableMemberDescriptor overridden) {
-            reportDelegationProblemIfRequired(VAR_OVERRIDDEN_BY_VAL_BY_DELEGATION, overriding, overridden);
+            reportDelegationProblemIfRequired(VAR_OVERRIDDEN_BY_VAL_BY_DELEGATION, null, overriding, overridden);
         }
 
         private void reportDelegationProblemIfRequired(
                 @NotNull DiagnosticFactory2<KtClassOrObject, CallableMemberDescriptor, CallableMemberDescriptor> diagnosticFactory,
+                @Nullable DiagnosticFactoryWithPsiElement<?, ?> relevantDiagnosticFromInheritance,
                 @NotNull CallableMemberDescriptor delegate,
                 @NotNull CallableMemberDescriptor overridden
         ) {
             assert delegate.getKind() == DELEGATION : "Delegate expected, got " + delegate + " of kind " + delegate.getKind();
 
-            if (!onceErrorsReported.contains(diagnosticFactory)) {
+            if (!onceErrorsReported.contains(diagnosticFactory) &&
+                    (relevantDiagnosticFromInheritance == null || !onceErrorsReported.contains(relevantDiagnosticFromInheritance))) {
                 onceErrorsReported.add(diagnosticFactory);
                 trace.report(diagnosticFactory.on(klass, delegate, overridden));
             }

compiler/testData/diagnostics/tests/delegation/covariantOverrides/fromClass.kt

@@ -0,0 +1,19 @@
+interface IBase1 {
+    fun foo(): Any
+}
+
+open class IDerived1 : IBase1 {
+    override fun foo(): String = "1"
+}
+
+<!RETURN_TYPE_MISMATCH_BY_DELEGATION!>class Broken1<!>(val b: IBase1) : IBase1 by b, IDerived1()
+
+interface IBase2 {
+    val foo: Any
+}
+
+open class IDerived2 : IBase2 {
+    override val foo: String = "2"
+}
+
+<!PROPERTY_TYPE_MISMATCH_BY_DELEGATION!>class Broken2<!>(val b: IBase2) : IBase2 by b, IDerived2()

compiler/testData/diagnostics/tests/delegation/covariantOverrides/fromClass.txt

@@ -0,0 +1,49 @@
+package
+
+public final class Broken1 : IBase1, IDerived1 {
+    public constructor Broken1(/*0*/ b: IBase1)
+    public final val b: IBase1
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*delegation*/ fun foo(): kotlin.Any
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Broken2 : IBase2, IDerived2 {
+    public constructor Broken2(/*0*/ b: IBase2)
+    public final val b: IBase2
+    public open override /*2*/ /*delegation*/ val foo: kotlin.Any
+    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 interface IBase1 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IBase2 {
+    public abstract val foo: kotlin.Any
+    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 open class IDerived1 : IBase1 {
+    public constructor IDerived1()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun foo(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class IDerived2 : IBase2 {
+    public constructor IDerived2()
+    public open override /*1*/ val foo: kotlin.String = "2"
+    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/delegation/covariantOverrides/irrelevant.kt

@@ -0,0 +1,19 @@
+interface IBase1 {
+    fun foo(): Any
+}
+
+interface IDerived1 {
+    fun foo(): String
+}
+
+<!RETURN_TYPE_MISMATCH_ON_INHERITANCE!>class Broken1<!>(val b: IBase1) : IBase1 by b, IDerived1
+
+interface IBase2 {
+    val foo: Any
+}
+
+interface IDerived2 {
+    val foo: String
+}
+
+<!PROPERTY_TYPE_MISMATCH_ON_INHERITANCE!>class Broken2<!>(val b: IBase2) : IBase2 by b, IDerived2

compiler/testData/diagnostics/tests/delegation/covariantOverrides/irrelevant.txt

@@ -0,0 +1,47 @@
+package
+
+public final class Broken1 : IBase1, IDerived1 {
+    public constructor Broken1(/*0*/ b: IBase1)
+    public final val b: IBase1
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*delegation*/ fun foo(): kotlin.Any
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Broken2 : IBase2, IDerived2 {
+    public constructor Broken2(/*0*/ b: IBase2)
+    public final val b: IBase2
+    public open override /*2*/ /*delegation*/ val foo: kotlin.Any
+    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 interface IBase1 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IBase2 {
+    public abstract val foo: kotlin.Any
+    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 interface IDerived1 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IDerived2 {
+    public abstract val foo: kotlin.String
+    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/delegation/covariantOverrides/kt13952.kt

@@ -0,0 +1,17 @@
+interface IA {
+    fun foo(): Number
+}
+
+interface IB : IA {
+    override fun foo(): Int
+}
+
+object AImpl : IA {
+    override fun foo() = 42
+}
+
+open <!RETURN_TYPE_MISMATCH_BY_DELEGATION!>class C<!> : IA by AImpl, IB
+
+class D : C() {
+    override fun foo(): Double = 3.14
+}

compiler/testData/diagnostics/tests/delegation/covariantOverrides/kt13952.txt

@@ -0,0 +1,39 @@
+package
+
+public object AImpl : IA {
+    private constructor AImpl()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun foo(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class C : IA, IB {
+    public constructor C()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*delegation*/ fun foo(): kotlin.Number
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class D : C {
+    public constructor D()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun foo(): kotlin.Double
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IA {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.Number
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IB : IA {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*1*/ fun foo(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/delegation/covariantOverrides/simple.kt

@@ -0,0 +1,19 @@
+interface IBase1 {
+    fun foo(): Any
+}
+
+interface IDerived1 : IBase1 {
+    override fun foo(): String
+}
+
+<!RETURN_TYPE_MISMATCH_BY_DELEGATION!>class Broken1<!>(val b: IBase1) : IBase1 by b, IDerived1
+
+interface IBase2 {
+    val foo: Any
+}
+
+interface IDerived2 : IBase2 {
+    override val foo: String
+}
+
+<!PROPERTY_TYPE_MISMATCH_BY_DELEGATION!>class Broken2<!>(val b: IBase2) : IBase2 by b, IDerived2

compiler/testData/diagnostics/tests/delegation/covariantOverrides/simple.txt

@@ -0,0 +1,47 @@
+package
+
+public final class Broken1 : IBase1, IDerived1 {
+    public constructor Broken1(/*0*/ b: IBase1)
+    public final val b: IBase1
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*delegation*/ fun foo(): kotlin.Any
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Broken2 : IBase2, IDerived2 {
+    public constructor Broken2(/*0*/ b: IBase2)
+    public final val b: IBase2
+    public open override /*2*/ /*delegation*/ val foo: kotlin.Any
+    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 interface IBase1 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IBase2 {
+    public abstract val foo: kotlin.Any
+    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 interface IDerived1 : IBase1 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*1*/ fun foo(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IDerived2 : IBase2 {
+    public abstract override /*1*/ val foo: kotlin.String
+    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

@@ -5780,6 +5780,39 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
             }
+
+            @TestMetadata("compiler/testData/diagnostics/tests/delegation/covariantOverrides")
+            @TestDataPath("$PROJECT_ROOT")
+            @RunWith(JUnit3RunnerWithInners.class)
+            public static class CovariantOverrides extends AbstractDiagnosticsTest {
+                public void testAllFilesPresentInCovariantOverrides() throws Exception {
+                    KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/delegation/covariantOverrides"), Pattern.compile("^(.+)\\.kt$"), true);
+                }
+
+                @TestMetadata("fromClass.kt")
+                public void testFromClass() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/delegation/covariantOverrides/fromClass.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("irrelevant.kt")
+                public void testIrrelevant() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/delegation/covariantOverrides/irrelevant.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("kt13952.kt")
+                public void testKt13952() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/delegation/covariantOverrides/kt13952.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("simple.kt")
+                public void testSimple() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/delegation/covariantOverrides/simple.kt");
+                    doTest(fileName);
+                }
+            }
         }
 
         @TestMetadata("compiler/testData/diagnostics/tests/deparenthesize")