Delegates to java defaults methods in compatibility mode

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/JvmDelegationFilter.kt

@@ -17,6 +17,8 @@
 package org.jetbrains.kotlin.resolve.jvm
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.config.LanguageVersion
+import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.load.java.descriptors.JavaMethodDescriptor
@@ -26,7 +28,8 @@ import org.jetbrains.kotlin.serialization.deserialization.PLATFORM_DEPENDENT_ANN
 
 object JvmDelegationFilter : DelegationFilter {
 
-    override fun filter(interfaceMember: CallableMemberDescriptor): Boolean {
+    override fun filter(interfaceMember: CallableMemberDescriptor, languageVersionSettings: LanguageVersionSettings): Boolean {
+        if (languageVersionSettings.languageVersion == LanguageVersion.KOTLIN_1_0) return true
         //We always have only one implementation otherwise it's an error in kotlin and java
         val realMember = DescriptorUtils.unwrapFakeOverride(interfaceMember)
         return !isJavaDefaultMethod(realMember) && !isBuiltInMemberMappedToJavaDefault(realMember)

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

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.resolve
 
+import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.DELEGATION
 import org.jetbrains.kotlin.diagnostics.Errors.MANY_IMPL_MEMBER_NOT_IMPLEMENTED
@@ -38,7 +39,8 @@ class DelegationResolver<T : CallableMemberDescriptor> private constructor(
         private val trace: BindingTrace,
         private val memberExtractor: MemberExtractor<T>,
         private val typeResolver: TypeResolver,
-        private val delegationFilter: DelegationFilter
+        private val delegationFilter: DelegationFilter,
+        private val languageVersionSettings: LanguageVersionSettings
 ) {
 
     private fun generateDelegatedMembers(): Collection<T> {
@@ -93,7 +95,7 @@ class DelegationResolver<T : CallableMemberDescriptor> private constructor(
         return memberExtractor.getMembersByType(interfaceType).filter { descriptor ->
             descriptor.isOverridable &&
             !classSupertypeMembers.any { isOverridableBy(it, descriptor) } &&
-            delegationFilter.filter(descriptor)
+            delegationFilter.filter(descriptor, languageVersionSettings)
         }
     }
 
@@ -113,9 +115,10 @@ class DelegationResolver<T : CallableMemberDescriptor> private constructor(
                 trace: BindingTrace,
                 memberExtractor: MemberExtractor<T>,
                 typeResolver: TypeResolver,
-                delegationFilter: DelegationFilter
+                delegationFilter: DelegationFilter,
+                languageVersionSettings: LanguageVersionSettings
         ): Collection<T> =
-                DelegationResolver(classOrObject, ownerDescriptor, existingMembers, trace, memberExtractor, typeResolver, delegationFilter)
+                DelegationResolver(classOrObject, ownerDescriptor, existingMembers, trace, memberExtractor, typeResolver, delegationFilter, languageVersionSettings)
                         .generateDelegatedMembers()
 
         private fun isOverridingAnyOf(

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/DelegationFilter.kt

@@ -16,13 +16,14 @@
 
 package org.jetbrains.kotlin.resolve.lazy
 
+import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 
 interface DelegationFilter {
 
-    fun filter(interfaceMember: CallableMemberDescriptor): Boolean
+    fun filter(interfaceMember: CallableMemberDescriptor, languageVersionSettings: LanguageVersionSettings): Boolean
 
     object DEFAULT : DelegationFilter {
-        override fun filter(interfaceMember: CallableMemberDescriptor) = true
+        override fun filter(interfaceMember: CallableMemberDescriptor, languageVersionSettings: LanguageVersionSettings) = true
     }
 }

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

@@ -295,7 +295,8 @@ open class LazyClassMemberScope(
                     extractor.extract(type, name)
         }
         return DelegationResolver.generateDelegatedMembers(
-                classOrObject, thisDescriptor, existingDescriptors, trace, lazyMemberExtractor, lazyTypeResolver, c.delegationFilter
+                classOrObject, thisDescriptor, existingDescriptors, trace, lazyMemberExtractor,
+                lazyTypeResolver, c.delegationFilter, c.languageVersionSettings
         )
     }
 

compiler/testData/codegen/java8/box/delegationBy/simple1.0.kt

@@ -0,0 +1,22 @@
+// LANGUAGE_VERSION: 1.0
+// FILE: Base.java
+
+public interface Base {
+    String getValue();
+
+    default String test() {
+        return getValue();
+    }
+}
+
+// FILE: main.kt
+class OK : Base {
+    override fun getValue() = "OK"
+}
+
+fun box(): String {
+    val z = object : Base by OK() {
+        override fun getValue() = "Fail"
+    }
+    return z.test()
+}

compiler/tests-java8/tests/org/jetbrains/kotlin/codegen/BlackBoxWithJava8CodegenTestGenerated.java

@@ -181,6 +181,12 @@ public class BlackBoxWithJava8CodegenTestGenerated extends AbstractBlackBoxCodeg
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/java8/box/delegationBy/simple.kt");
             doTest(fileName);
         }
+
+        @TestMetadata("simple1.0.kt")
+        public void testSimple1_0() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/java8/box/delegationBy/simple1.0.kt");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("compiler/testData/codegen/java8/box/jvm8")