struct dynamic allocation error

[Dechcaudron via Digitalmars-d]

On Thursday, 15 September 2016 at 21:21:12 UTC, Steven 
Schveighoffer wrote:
> You need to destroy structs by passing them by reference. 
> Passing a pointer just destroys the pointer.
>
> In this example, you can destroy what b points at (and call its 
> destructor) via:
>
> destroy(*b);
>
> However, this will not fix the issue. This is because the 
> memory block is not marked as being destroyed already (so it 
> will run the dtor again). Class instances have a feature 
> whereby when you call destroy it marks the memory block as 
> already having the destructor run. Structs do not have this 
> feature. Classes can afford to store extra metadata, structs 
> cannot.
>
> So the true fix here is to avoid allocating in the destructor 
> (which is a no-no for heap-allocated items). This may work, it 
> may not:
>
> writefln("a is %s", a);

That makes it work. Thanks a lot! I thought the GC knew what had 
already been destroyed, though. Thanks for letting me know that 
only works for classes, that'll spare me a lot of trouble. Having 
the destructor be run twice can be a bit of a hassle, but it's 
nothing I can't find a workaround for.

Thank you all who replied! I'm sorry I chose the General room 
instead of the Learn one. I really thought this was some kind of 
bug (although it's pretty obvious it would've been reported by 
someone else if it was).