Report warning on hided override by delegation when compile to 1.0 version

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

@@ -245,7 +245,7 @@ public interface Errors {
     DiagnosticFactory0<KtSuperTypeEntry> SUPERTYPE_NOT_INITIALIZED = DiagnosticFactory0.create(ERROR);
 
     DiagnosticFactory0<KtTypeReference> DELEGATION_NOT_TO_INTERFACE = DiagnosticFactory0.create(ERROR);
-    DiagnosticFactory2<KtDeclaration, CallableMemberDescriptor, List<CallableMemberDescriptor>> DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE = DiagnosticFactory2.create(ERROR);
+    DiagnosticFactory2<KtDeclaration, CallableMemberDescriptor, List<CallableMemberDescriptor>> DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE = DiagnosticFactory2.create(WARNING);
     DiagnosticFactory0<KtTypeReference> SUPERTYPE_NOT_A_CLASS_OR_INTERFACE = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtTypeReference> SUPERTYPE_IS_EXTENSION_FUNCTION_TYPE = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtTypeReference> SUPERTYPE_IS_SUSPEND_FUNCTION_TYPE = DiagnosticFactory0.create(ERROR);

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

@@ -16,7 +16,6 @@
 
 package org.jetbrains.kotlin.resolve.checkers
 
-import org.jetbrains.kotlin.config.LanguageVersion
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
@@ -40,8 +39,6 @@ class DelegationChecker : DeclarationChecker {
             bindingContext: BindingContext,
             languageVersionSettings: LanguageVersionSettings
     ) {
-        if (languageVersionSettings.languageVersion == LanguageVersion.KOTLIN_1_0) return
-
         if (descriptor !is ClassDescriptor) return
         if (declaration !is KtClassOrObject) return
 

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simple1.0.kt

@@ -0,0 +1,21 @@
+// !LANGUAGE_VERSION: 1.0
+
+public interface Base {
+    fun getValue(): String
+
+    fun test() = getValue()
+}
+
+class Delegate : Base {
+    override fun getValue() = "Delegate"
+}
+
+public abstract class MyClass : Base {
+    override fun test(): String {
+        return "Class"
+    }
+}
+
+<!DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE!>class A : MyClass(), Base by Delegate() {
+    override fun getValue() = "Delegate"
+}<!>

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simple1.0.txt

@@ -0,0 +1,36 @@
+package
+
+public final class A : MyClass, Base {
+    public constructor A()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ fun getValue(): kotlin.String
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*delegation*/ fun test(): kotlin.String
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface Base {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun getValue(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open fun test(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Delegate : Base {
+    public constructor Delegate()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun getValue(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun test(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public abstract class MyClass : Base {
+    public constructor MyClass()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*1*/ /*fake_override*/ fun getValue(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ fun test(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests-common/org/jetbrains/kotlin/checkers/BaseDiagnosticsTest.kt

@@ -36,6 +36,7 @@ import org.jetbrains.kotlin.psi.KtDeclaration
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.MultiTargetPlatform
+import org.jetbrains.kotlin.test.InTextDirectivesUtils
 import org.jetbrains.kotlin.test.KotlinTestUtils
 import org.jetbrains.kotlin.utils.addIfNotNull
 import org.junit.Assert
@@ -275,6 +276,7 @@ abstract class BaseDiagnosticsTest : KotlinMultiFileTestWithJava<TestModule, Tes
         )
 
         val LANGUAGE_DIRECTIVE = "LANGUAGE"
+        val LANGUAGE_VERSION = "LANGUAGE_VERSION"
         private val LANGUAGE_PATTERN = Pattern.compile("([\\+\\-])(\\w+)\\s*")
 
         val API_VERSION_DIRECTIVE = "API_VERSION"
@@ -302,14 +304,17 @@ abstract class BaseDiagnosticsTest : KotlinMultiFileTestWithJava<TestModule, Tes
         private fun parseLanguageVersionSettings(directiveMap: Map<String, String>): LanguageVersionSettings? {
             val apiVersionString = directiveMap[API_VERSION_DIRECTIVE]
             val directives = directiveMap[LANGUAGE_DIRECTIVE]
-            if (apiVersionString == null && directives == null) return null
+            val languageVersionDirective = directiveMap[LANGUAGE_VERSION]
+            if (apiVersionString == null && directives == null && languageVersionDirective == null) return null
 
             val apiVersion = (if (apiVersionString != null) ApiVersion.parse(apiVersionString) else ApiVersion.LATEST)
                              ?: error("Unknown API version: $apiVersionString")
 
             val languageFeatures = directives?.let(this::collectLanguageFeatureMap).orEmpty()
 
-            return DiagnosticTestLanguageVersionSettings(languageFeatures, apiVersion, LanguageVersion.LATEST)
+            val languageVersion: LanguageVersion = languageVersionDirective?.let { LanguageVersion.fromVersionString(it) } ?: LanguageVersion.LATEST
+
+            return DiagnosticTestLanguageVersionSettings(languageFeatures, apiVersion, languageVersion)
         }
 
         private fun collectLanguageFeatureMap(directives: String): Map<LanguageFeature, Boolean> {

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

@@ -6462,6 +6462,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("simple1.0.kt")
+                public void testSimple1_0() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simple1.0.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("simpleNoOverride.kt")
                 public void testSimpleNoOverride() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleNoOverride.kt");

idea/testData/quickfix/abstract/manyImpl.kt

@@ -1,6 +1,5 @@
 // "Make 'A' abstract" "false"
 // ERROR: Class 'X' must override public open fun foo(): Unit defined in X because it inherits many implementations of it
-// ERROR: Delegated member 'fun foo(): Unit' hides supertype override: public open fun foo(): Unit defined in E. Please specify proper override explicitly
 // ACTION: Create test
 // ACTION: Make internal
 // ACTION: Make private