alias this and null reference

[Namespace]

On Friday, 27 April 2012 at 17:08:43 UTC, Simen Kjaeraas wrote:
> On Friday, 27 April 2012 at 16:57:52 UTC, Namespace wrote:
>> On Friday, 27 April 2012 at 16:49:49 UTC, Simen Kjaeraas wrote:
>>> On Friday, 27 April 2012 at 16:36:04 UTC, Namespace wrote:
>>>> By the following code i get a normal Access Violation.
>>>> My question is: why? Even if "f0" is null, the object must be
>>>> converted to Ref and there i check if the given object is 
>>>> null.
>>>
>>> When trying to convert f0 to Ref, the compiler has to look in 
>>> the
>>> vtable for the getRef function. The vtable is in a nonsensical
>>> place when the class reference is null, and thus it bails out.
>>>
>>> Solution: mark getRef as final.
>>
>> Great, thank you for reply, it works :).
>> It is maybe possible, that I get another error output as "null 
>> this"?
>> Maybe an assert or something else?
>
> Now we're delving into some deep magic of the compiler. In 
> non-release builds, the compiler adds a pre-function invariant, 
> which is called before the function is called. This invariant 
> contains the equivalent of assert(this !is null, "null this");, 
> and this is what you run into.
>
> There's currently no way to get rid of this but to compile for 
> release, in which case your own assert also goes out the window.


I see, too bad.
What could i do if i'm in release mode and will throw such error 
message?