Write KotlinInterfaceDefaultImpls annotation to DefaultImpls classes

Instead of KotlinSyntheticClass with kind = TRAIT_IMPL

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/JvmAnnotationNames.java

@@ -34,6 +34,7 @@ public final class JvmAnnotationNames {
     public static final FqName KOTLIN_MULTIFILE_CLASS = new FqName("kotlin.jvm.internal.KotlinMultifileClass");
     public static final FqName KOTLIN_MULTIFILE_CLASS_PART = new FqName("kotlin.jvm.internal.KotlinMultifileClassPart");
     public static final FqName KOTLIN_CALLABLE = new FqName("kotlin.jvm.internal.KotlinCallable");
+    public static final FqName KOTLIN_INTERFACE_DEFAULT_IMPLS = new FqName("kotlin.jvm.internal.KotlinInterfaceDefaultImpls");
 
     public static final FqName JAVA_LANG_DEPRECATED = new FqName("java.lang.Deprecated");
 
@@ -139,6 +140,7 @@ public final class JvmAnnotationNames {
             SPECIAL_ANNOTATIONS.add(JvmClassName.byFqNameWithoutInnerClasses(fqName));
         }
         SPECIAL_ANNOTATIONS.add(KotlinSyntheticClass.CLASS_NAME);
+        SPECIAL_ANNOTATIONS.add(JvmClassName.byFqNameWithoutInnerClasses(KOTLIN_INTERFACE_DEFAULT_IMPLS));
 
         for (FqName fqName : Arrays.asList(JETBRAINS_NOT_NULL_ANNOTATION, JETBRAINS_NULLABLE_ANNOTATION)) {
             NULLABILITY_ANNOTATIONS.add(JvmClassName.byFqNameWithoutInnerClasses(fqName));

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/header/KotlinClassHeader.kt

@@ -29,7 +29,8 @@ public class KotlinClassHeader(
         public val classKind: KotlinClass.Kind?,
         public val syntheticClassKind: KotlinSyntheticClass.Kind?,
         public val filePartClassNames: Array<String>?,
-        public val multifileClassName: String?
+        public val multifileClassName: String?,
+        public val isInterfaceDefaultImpls: Boolean
 ) {
     public val isCompatibleAbiVersion: Boolean get() = AbiVersionUtil.isAbiVersionCompatible(version)
 

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/header/ReadKotlinClassHeaderAnnotationVisitor.java

@@ -68,6 +68,7 @@ public class ReadKotlinClassHeaderAnnotationVisitor implements AnnotationVisitor
     private KotlinClassHeader.Kind headerKind = null;
     private KotlinClass.Kind classKind = null;
     private KotlinSyntheticClass.Kind syntheticClassKind = null;
+    private boolean isInterfaceDefaultImpls = false;
 
     @Nullable
     public KotlinClassHeader createHeader() {
@@ -81,17 +82,17 @@ public class ReadKotlinClassHeaderAnnotationVisitor implements AnnotationVisitor
         }
 
         if (!AbiVersionUtil.isAbiVersionCompatible(version)) {
-            return new KotlinClassHeader(headerKind, version, null, strings, classKind, syntheticClassKind, null, null);
+            annotationData = null;
         }
-
-        if (shouldHaveData() && annotationData == null) {
+        else if (shouldHaveData() && annotationData == null) {
             // This means that the annotation is found and its ABI version is compatible, but there's no "data" string array in it.
             // We tell the outside world that there's really no annotation at all
             return null;
         }
 
         return new KotlinClassHeader(
-                headerKind, version, annotationData, strings, classKind, syntheticClassKind, filePartClassNames, multifileClassName
+                headerKind, version, annotationData, strings, classKind, syntheticClassKind, filePartClassNames, multifileClassName,
+                isInterfaceDefaultImpls
         );
     }
 
@@ -105,6 +106,11 @@ public class ReadKotlinClassHeaderAnnotationVisitor implements AnnotationVisitor
     @Nullable
     @Override
     public AnnotationArgumentVisitor visitAnnotation(@NotNull ClassId classId, @NotNull SourceElement source) {
+        if (KOTLIN_INTERFACE_DEFAULT_IMPLS.equals(classId.asSingleFqName())) {
+            isInterfaceDefaultImpls = true;
+            return null;
+        }
+
         if (headerKind != null) {
             // Ignore all Kotlin annotations except the first found
             return null;

core/runtime.jvm/src/kotlin/jvm/internal/KotlinInterfaceDefaultImpls.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2010-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kotlin.jvm.internal;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface KotlinInterfaceDefaultImpls {
+    int[] version() default {};
+}