Add support for javascript incompatibility warnings.

runtime/lib/object.cc

Index: runtime/lib/object.cc
===================================================================
--- runtime/lib/object.cc	(revision 35921)
+++ runtime/lib/object.cc	(working copy)
@@ -16,6 +16,7 @@
 
 DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(bool, trace_type_checks);
+DECLARE_FLAG(bool, warn_on_javascript_incompatibility);
 
 
 DEFINE_NATIVE_ENTRY(Object_equals, 1) {
@@ -109,6 +110,41 @@
 }
 
 
+static void WarnOnJSIntegralNumTypeTest(
+    const Instance& instance,
+    const TypeArguments& instantiator_type_arguments,
+    const AbstractType& type) {
+  const bool instance_is_int =
+      instance.IsSmi() || instance.IsMint() || instance.IsBigint();

[srdjan, 2014/05/08 18:11:05]

Why not instance.IsInteger()? 

[regis, 2014/05/09 21:03:42]

Done.

+  const bool instance_is_double = instance.IsDouble();
+  if (!(instance_is_int || instance_is_double)) {
+    return;
+  }
+  AbstractType& instantiated_type = AbstractType::Handle(type.raw());
+  if (!type.IsInstantiated()) {
+    instantiated_type = type.InstantiateFrom(instantiator_type_arguments, NULL);
+  }
+  if (instance_is_double) {
+    if (instantiated_type.IsIntType()) {
+      const double value = Double::Cast(instance).value();
+      if (floor(value) == value) {
+        Exceptions::JSWarning(ICData::Handle(),  // ic_data must be looked up.
+                              "javascript incompatibility: integral value of "
+                              "type 'double' is also considered to be of "
+                              "type 'int'");
+      }
+    }
+  } else {
+    ASSERT(instance_is_int);
+    if (instantiated_type.IsDoubleType()) {
+      Exceptions::JSWarning(ICData::Handle(),  // ic_data must be looked up.
+                            "javascript incompatibility: integer value is "
+                            "also considered to be of type 'double'");
+    }
+  }
+}
+
+
 DEFINE_NATIVE_ENTRY(Object_instanceOf, 5) {
   const Instance& instance = Instance::CheckedHandle(arguments->NativeArgAt(0));
   // Instantiator at position 1 is not used. It is passed along so that the call
@@ -122,6 +158,12 @@
   ASSERT(type.IsFinalized());
   ASSERT(!type.IsMalformed());
   ASSERT(!type.IsMalbounded());
+
+  // Check for javascript incompatibility.
+  if (FLAG_warn_on_javascript_incompatibility) {
+    WarnOnJSIntegralNumTypeTest(instance, instantiator_type_arguments, type);
+  }
+
   Error& bound_error = Error::Handle();
   const bool is_instance_of = instance.IsInstanceOf(type,
                                                     instantiator_type_arguments,
@@ -170,6 +212,12 @@
   if (instance.IsNull()) {
     return instance.raw();
   }
+
+  // Check for javascript incompatibility.
+  if (FLAG_warn_on_javascript_incompatibility) {
+    WarnOnJSIntegralNumTypeTest(instance, instantiator_type_arguments, type);
+  }
+
   const bool is_instance_of = instance.IsInstanceOf(type,
                                                     instantiator_type_arguments,
                                                     &bound_error);