Devirtualization: bug fix

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/optimizations/Devirtualization.kt

@@ -355,6 +355,7 @@ internal object Devirtualization {
                             if (node.receiverType == DataFlowIR.Type.Virtual)
                                 continue@nodeLoop
                             val receiverType = node.receiverType.resolved()
+                            val vCallReturnType = node.returnType.resolved()
 
                             DEBUG_OUTPUT(1) {
                                 println("Adding virtual callsite:")
@@ -368,6 +369,12 @@ internal object Devirtualization {
                                         .forEach { println("        $it") }
                             }
 
+                            if (entryPoint == null && vCallReturnType.isFinal) {
+                                // If we are in a library and facing final return type then
+                                // this type can be returned by some user of this library, so propagate it explicitly.
+                                addInstantiatingClass(vCallReturnType)
+                            }
+
                             typesVirtualCallSites.getOrPut(receiverType, { mutableListOf() }).add(node)
                             typeHierarchy.inheritorsOf(receiverType)
                                     .filter { instantiatingClasses.contains(it) }