From 618468511118ed3fcbffe241eb4692e058db8f29 Mon Sep 17 00:00:00 2001
From: Sergey Bogolepov <ace.is.not.my.card@gmail.com>
Date: Thu, 9 Aug 2018 14:27:08 +0300
Subject: [PATCH] Verbose ClassCastException

---
 runtime/src/main/cpp/Exceptions.h                      | 2 +-
 runtime/src/main/cpp/Types.cpp                         | 2 +-
 runtime/src/main/kotlin/konan/internal/RuntimeUtils.kt | 5 +++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/runtime/src/main/cpp/Exceptions.h b/runtime/src/main/cpp/Exceptions.h
index 654b5c4364d..0ee9b6bee15 100644
--- a/runtime/src/main/cpp/Exceptions.h
+++ b/runtime/src/main/cpp/Exceptions.h
@@ -39,7 +39,7 @@ void RUNTIME_NORETURN ThrowNullPointerException();
 // Context is evaluated from caller's address.
 void RUNTIME_NORETURN ThrowArrayIndexOutOfBoundsException();
 // Throws class cast exception.
-void RUNTIME_NORETURN ThrowClassCastException();
+void RUNTIME_NORETURN ThrowClassCastException(const ObjHeader* instance, const TypeInfo* type_info);
 // Throws arithmetic exception.
 void RUNTIME_NORETURN ThrowArithmeticException();
 // Throws number format exception.
diff --git a/runtime/src/main/cpp/Types.cpp b/runtime/src/main/cpp/Types.cpp
index 2ca4e6e67e4..b5d84d94826 100644
--- a/runtime/src/main/cpp/Types.cpp
+++ b/runtime/src/main/cpp/Types.cpp
@@ -47,7 +47,7 @@ void CheckInstance(const ObjHeader* obj, const TypeInfo* type_info) {
   if (IsInstance(obj, type_info)) {
     return;
   }
-  ThrowClassCastException();
+  ThrowClassCastException(obj, type_info);
 }
 
 KBoolean Kotlin_TypeInfo_isInstance(KConstRef obj, KNativePtr typeInfo) {
diff --git a/runtime/src/main/kotlin/konan/internal/RuntimeUtils.kt b/runtime/src/main/kotlin/konan/internal/RuntimeUtils.kt
index 899420a93de..9beba050415 100644
--- a/runtime/src/main/kotlin/konan/internal/RuntimeUtils.kt
+++ b/runtime/src/main/kotlin/konan/internal/RuntimeUtils.kt
@@ -30,8 +30,9 @@ internal fun ThrowArrayIndexOutOfBoundsException(): Nothing {
 }
 
 @ExportForCppRuntime
-fun ThrowClassCastException(): Nothing {
-    throw ClassCastException()
+fun ThrowClassCastException(instance: Any, typeInfo: NativePtr): Nothing {
+    val clazz = KClassImpl<Any>(typeInfo)
+    throw ClassCastException("${instance::class.qualifiedName} cannot be cast to ${clazz.qualifiedName}")
 }
 
 fun ThrowTypeCastException(): Nothing {