Load default values for annotation members from classfiles

so that defaults are available to synthetic implementations.

#KT-48181 Fixed

Implementation is for JVM IR; other backends & FIR need to be supported
separately.

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/AnnotationAndConstantLoader.kt

@@ -78,4 +78,10 @@ interface AnnotationAndConstantLoader<out A : Any, out C : Any> {
         proto: ProtoBuf.Property,
         expectedType: KotlinType
     ): C?
+
+    fun loadAnnotationDefaultValue(
+        container: ProtoContainer,
+        proto: ProtoBuf.Property,
+        expectedType: KotlinType
+    ): C?
 }

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/AnnotationAndConstantLoaderImpl.kt

@@ -104,4 +104,13 @@ class AnnotationAndConstantLoaderImpl(
         val value = proto.getExtensionOrNull(protocol.compileTimeValue) ?: return null
         return deserializer.resolveValue(expectedType, value, container.nameResolver)
     }
+
+    override fun loadAnnotationDefaultValue(
+        container: ProtoContainer,
+        proto: ProtoBuf.Property,
+        expectedType: KotlinType
+    ): ConstantValue<*>? {
+        // Implement this method to properly support Annotations Instantiation feature
+        return null
+    }
 }

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/MemberDeserializer.kt

@@ -140,6 +140,15 @@ class MemberDeserializer(private val c: DeserializationContext) {
             )
         }
 
+        if ((c.containingDeclaration as? ClassDescriptor)?.kind == ClassKind.ANNOTATION_CLASS) {
+            property.setCompileTimeInitializer(
+                c.storageManager.createNullableLazyValue {
+                    val container = c.containingDeclaration.asProtoContainer()!!
+                    c.components.annotationAndConstantLoader.loadAnnotationDefaultValue(container, proto, property.returnType)
+                }
+            )
+        }
+
         property.initialize(
             getter, setter,
             FieldDescriptorImpl(getPropertyFieldAnnotations(proto, isDelegate = false), property),