Struct with default ctor (Was: [dmd-beta] dmd 2.064 beta take 2)

[Idan Arye]

On Sunday, 19 May 2013 at 23:07:00 UTC, deadalnix wrote:
> On Sunday, 19 May 2013 at 22:32:58 UTC, Andrei Alexandrescu 
> wrote:
>> How was there a bug if everything was properly synchronized? 
>> You either describe the matter with sufficient detail, or 
>> acknowledge the destruction of your anecdote. This is going 
>> nowhere.
>>
>
> I explained over and over. A field is initialized to null, 
> while the object lock is owned, and later to its value, while 
> it is locked. In the meantime, another thread access the 
> object, owning the lock, assuming the field is always 
> initialized.
>
> The exact same problem arise quite often in the single threaded 
> world : a reference is set to null, the dev try to be clever 
> when initializing it, in a rare case it isn't, and everything 
> blows up when it occurs.
>
> It is simply easier to reproduce when things are single 
> threaded, and are often quickly debugged in that case.
>
> As explained, the multithreaded environment makes it super hard 
> to debug, not the primary cause of the issue. The simply 
> consistent in moving the initialization where it was set to 
> null in the first place.
>
> It is an instance of the very classic something may be null and 
> code use it assuming it is never null.

So this is not a problem of nullableness - rather this is a 
problem of mutability.