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));
             }