Fix issue 14366: in case of a type check error and conflicting type names being the same, prefix ty…

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
===================================================================
--- runtime/vm/code_generator.cc	(revision 31614)
+++ runtime/vm/code_generator.cc	(working copy)
@@ -616,22 +616,41 @@
     // Throw a dynamic type error.
     const intptr_t location = GetCallerLocation();
     const AbstractType& src_type = AbstractType::Handle(src_instance.GetType());
-    const String& src_type_name = String::Handle(src_type.UserVisibleName());
+    String& src_type_name = String::Handle(src_type.UserVisibleName());
     String& dst_type_name = String::Handle();
+    Library& dst_type_lib = Library::Handle();
     if (!dst_type.IsInstantiated()) {
       // Instantiate dst_type before reporting the error.
       const AbstractType& instantiated_dst_type = AbstractType::Handle(
           dst_type.InstantiateFrom(instantiator_type_arguments, NULL));
       // Note that instantiated_dst_type may be malbounded.
       dst_type_name = instantiated_dst_type.UserVisibleName();
+      dst_type_lib =
+          Class::Handle(instantiated_dst_type.type_class()).library();
     } else {
       dst_type_name = dst_type.UserVisibleName();
+      dst_type_lib = Class::Handle(dst_type.type_class()).library();
     }
     String& bound_error_message =  String::Handle();
     if (!bound_error.IsNull()) {
       ASSERT(FLAG_enable_type_checks);
       bound_error_message = String::New(bound_error.ToErrorCString());
     }
+    if (src_type_name.Equals(dst_type_name)) {
+      // Qualify the names with their libraries.
+      String& lib_name = String::Handle();
+      lib_name = Library::Handle(
+          Class::Handle(src_type.type_class()).library()).name();
+      if (lib_name.Length() != 0) {
+        lib_name = String::Concat(lib_name, Symbols::Dot());
+        src_type_name = String::Concat(lib_name, src_type_name);
+      }
+      lib_name = dst_type_lib.name();
+      if (lib_name.Length() != 0) {
+        lib_name = String::Concat(lib_name, Symbols::Dot());
+        dst_type_name = String::Concat(lib_name, dst_type_name);
+      }
+    }
     Exceptions::CreateAndThrowTypeError(location, src_type_name, dst_type_name,
                                         dst_name, bound_error_message);
     UNREACHABLE();