[Issue 2834] Struct Destructors are not called by the GC, but called on explicit delete.

[Sean Kelly]

<d-bugmail at puremagic.com> wrote:
> http://d.puremagic.com/issues/show_bug.cgi?id=2834
> 
> 
> Max Samukha <samukha at voliacable.com> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                  CC|                           
> |samukha at voliacable.com
> 
> 
> --- Comment #8 from Max Samukha <samukha at voliacable.com> 2010-11-18
> 03:39:17 PST ---
> So what is the verdict? Should we simply specify that struct
> destructors are
> not automatically called except in RAII and remove the struct-in-class
> special
> case?
> 
> BTW, there are other problems (serious IMO):
> 
> auto ss = new S[10];
> ss.length = 5;
> delete ss; 
> 
> Destructors are not called on the last 5 elements.
> 
> ----
> auto ss = new S[10];
> ss ~= ss;
> delete ss;
> 
> We have a nasty problem when destructors are called on the appended
> elements
> because postblits was not run for them during append.
> 
> etc
> 
> Essentially, operations on arrays of structs with postblits/dtors
> defined are
> currently unusable.

I think this is unavoidable. Consider:

auto a = new T[5];
auto b = a[4..5];
a.length = 4;

We can't safely destroy a[4] because it's aliased. Also, since there's
no concept of an owner reference vs an alias, modifying the length of b
could screw up a as well. 

For this and other reasons I'm inclined to withdraw this issue, and
declare that since structs are value types they won't be automatically
destroyed when collected by the GC or when held in arrays.