It is unclear what the correct handling is for JavaScriptCore. (Nobody bothers to document this in JSCore.) Unlike our other problem where we incorrectly assume JSObjectRef when the functions want JSValueRef, this time Apple is demanding the JSObjectRef. Like our other problem, I assume it is unsafe to try to convert Undefined into a JSObjectRef.
So reverting to NULL seems like the safer bet for this specific case. Perhaps the other alternative is to return an exception object or an error object. But I would like to see JSCore document this before trying.
According to this:
http://parmanoir.com/Taming_JavascriptCore_within_and_without_WebView
Returning NULL instead of an actual JSValueRef for a return value of a function could lead to crashes. I think I have seen related weirdness in the past when I failed to return a proper type to JSCore which resulted in very hard to understand behavior.
So this patch changes those return NULLs to return JSValueMakeUndefined().
I thought about JSObjectMakeError, but I don't fully understand the intent of the Error object and can't find any relevant real world examples of it being used. However, everybody seems to be using JSValueMakeUndefined().
This patch should be low impact since this is only triggered on an error condition.
I did not realize this branch has some JavaScriptCore stuff in it too. Unfortunately, it seems to have its own unique problems (like creating C++ files when it should be generating C files). My changes are targeted for v8, and I don't think my JSCore changes fully reach in this JSCore implementation so more work would need to be done to get this branch working. I think my Neha fork is in better shape at the moment.
Also, I did port over the 'NULL out the dtor function pointer' in the %nodefaultdtor fix to v8.
Usage case:
struct MyData {
%extend {
~MyData() {
FreeData($self);
}
}
};
%newobject CreateData;
struct MyData* CreateData(void);
%delobject FreeData;
void FreeData(struct MyData* the_data);
where the use case is something like:
var my_data = example.CreateData();
my_data = null;
