Generate 'DefaultImpls' for jvm 8 target only within compiler option

compiler/backend/src/org/jetbrains/kotlin/codegen/FunctionCodegen.java

@@ -79,6 +79,7 @@ import java.util.Set;
 import static org.jetbrains.kotlin.builtins.KotlinBuiltIns.isNullableAny;
 import static org.jetbrains.kotlin.codegen.AsmUtil.*;
 import static org.jetbrains.kotlin.codegen.JvmCodegenUtil.isAnnotationOrJvm6Interface;
+import static org.jetbrains.kotlin.codegen.JvmCodegenUtil.isJvm8Interface;
 import static org.jetbrains.kotlin.codegen.JvmCodegenUtil.isJvm8InterfaceMember;
 import static org.jetbrains.kotlin.codegen.serialization.JvmSerializationBindings.METHOD_FOR_FUNCTION;
 import static org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.DECLARATION;
@@ -163,9 +164,7 @@ public class FunctionCodegen {
         OwnerKind contextKind = methodContext.getContextKind();
         if (isInterface(functionDescriptor.getContainingDeclaration()) &&
             functionDescriptor.getVisibility() == Visibilities.PRIVATE &&
-            (isJvm8InterfaceMember(functionDescriptor, state)
-             ? contextKind == OwnerKind.DEFAULT_IMPLS
-             : contextKind != OwnerKind.DEFAULT_IMPLS)) {
+            !processInterfaceMember(functionDescriptor, contextKind, state)) {
             return;
         }
 
@@ -199,7 +198,7 @@ public class FunctionCodegen {
 
         generateBridges(functionDescriptor);
 
-        if (isJvm8InterfaceMember(functionDescriptor, state) && contextKind != OwnerKind.DEFAULT_IMPLS) {
+        if (isJvm8InterfaceMember(functionDescriptor, state) && contextKind != OwnerKind.DEFAULT_IMPLS && state.getGenerateDefaultImplsForJvm8()) {
             generateDelegateForDefaultImpl(functionDescriptor, origin.getElement());
         }
 
@@ -771,7 +770,7 @@ public class FunctionCodegen {
     ) {
         DeclarationDescriptor contextClass = owner.getContextDescriptor().getContainingDeclaration();
 
-        if (kind != OwnerKind.DEFAULT_IMPLS && isInterface(contextClass)) {
+        if (isInterface(contextClass) && !processInterface(contextClass, kind, state)) {
             return;
         }
 
@@ -1157,4 +1156,21 @@ public class FunctionCodegen {
                 }
         );
     }
+
+    public static boolean processInterfaceMember(
+            @NotNull CallableMemberDescriptor function,
+            @NotNull OwnerKind kind,
+            @NotNull GenerationState state
+    ) {
+        return processInterface(function.getContainingDeclaration(), kind, state);
+    }
+
+    public static boolean processInterface(
+            @NotNull DeclarationDescriptor contextClass,
+            @NotNull OwnerKind kind,
+            @NotNull GenerationState state
+    ) {
+        assert isInterface(contextClass) : "'processInterface' method should be called only for interfaces, but: " + contextClass;
+        return isJvm8Interface(contextClass, state) ? kind != OwnerKind.DEFAULT_IMPLS : kind == OwnerKind.DEFAULT_IMPLS;
+    }
 }

compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java

@@ -231,7 +231,7 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
 
     @Override
     protected void generateDefaultImplsIfNeeded() {
-        if (isInterface(descriptor) && !isLocal) {
+        if (isInterface(descriptor) && !isLocal && (!isJvm8Interface(descriptor, state) || state.getGenerateDefaultImplsForJvm8())) {
             Type defaultImplsType = state.getTypeMapper().mapDefaultImpls(descriptor);
             ClassBuilder defaultImplsBuilder =
                     state.getFactory().newVisitor(JvmDeclarationOriginKt.DefaultImpls(myClass, descriptor), defaultImplsType, myClass.getContainingFile());

compiler/backend/src/org/jetbrains/kotlin/codegen/JvmCodegenUtil.java

@@ -79,7 +79,7 @@ public class JvmCodegenUtil {
         return !state.isJvm8Target();
     }
 
-    private static boolean isJvm8Interface(@NotNull DeclarationDescriptor descriptor, @NotNull GenerationState state) {
+    public static boolean isJvm8Interface(@NotNull DeclarationDescriptor descriptor, @NotNull GenerationState state) {
         return DescriptorUtils.isInterface(descriptor) && !isAnnotationOrJvm6Interface(descriptor, state);
     }
 

compiler/backend/src/org/jetbrains/kotlin/codegen/PropertyCodegen.java

@@ -275,7 +275,8 @@ public class PropertyCodegen {
 
         DeclarationDescriptor contextDescriptor = context.getContextDescriptor();
         if (!isInterface(contextDescriptor) ||
-            (isJvm8Interface(contextDescriptor, state) ? kind != OwnerKind.DEFAULT_IMPLS : kind == OwnerKind.DEFAULT_IMPLS)) {
+            (FunctionCodegen.processInterface(contextDescriptor, kind, state) ||
+             (kind == OwnerKind.DEFAULT_IMPLS && state.getGenerateDefaultImplsForJvm8()))) {
             int flags = ACC_DEPRECATED | ACC_PRIVATE | ACC_STATIC | ACC_SYNTHETIC;
             Method syntheticMethod = getSyntheticMethodSignature(descriptor);
             MethodVisitor mv = v.newMethod(JvmDeclarationOriginKt.OtherOrigin(descriptor), flags, syntheticMethod.getName(),

compiler/backend/src/org/jetbrains/kotlin/codegen/state/GenerationState.kt

@@ -157,6 +157,7 @@ class GenerationState @JvmOverloads constructor(
     val useTypeTableInSerializer: Boolean = configuration.getBoolean(JVMConfigurationKeys.USE_TYPE_TABLE)
     val inheritMultifileParts: Boolean = configuration.getBoolean(JVMConfigurationKeys.INHERIT_MULTIFILE_PARTS)
     val isJvm8Target: Boolean = configuration.get(JVMConfigurationKeys.JVM_TARGET) == JvmTarget.JVM_1_8
+    val generateDefaultImplsForJvm8: Boolean = configuration.getBoolean(JVMConfigurationKeys.INTERFACE_COMPATIBILITY)
 
     val rootContext: CodegenContext<*> = RootContext(this)