Prevent calls to ReturnValue::Set with pointer-valued types.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 4d99d151522b98b22d8d10fc2ec5e2f0b77e7798..ceb57c0abd3cafc1d228da2d8efbd72ee324d02f 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -2458,6 +2458,9 @@ class ReturnValue {
   // Convenience getter for Isolate
   V8_INLINE Isolate* GetIsolate();
 
+  // Pointer setter: Uncompilable to prevent inadvertent misuse.
+  void Set(void* whatever);
+
  private:
   template<class F> friend class ReturnValue;
   template<class F> friend class FunctionCallbackInfo;
@@ -5981,6 +5984,12 @@ Isolate* ReturnValue<T>::GetIsolate() {
 }
 
 template<typename T>
+void ReturnValue<T>::Set(void* whatever) {
+  // Uncompilable to prevent inadvertent misuse.
+  TYPE_CHECK(void*, Primitive);
+}
+
+template<typename T>
 internal::Object* ReturnValue<T>::GetDefaultValue() {
   // Default value is always the pointer below value_ on the stack.
   return value_[-1];