why does clearing an array set its capacity to 0?

[Vlad Levenfeld via Digitalmars-d-learn]

> How did you allocate your array? The GC has the APPENDABLE 
> attribute special for memory blocks that are going to be used 
> as slices:

I allocated with new T[n]. I've tried allocating with both the 
APPENDABLE and NO_SCAN blocks but beyond a certain allocation 
size this doesn't work, I get a reported capacity of 0 and any 
append reallocates. (8000 does it for me, I haven't looked for 
the lower bound)

> Are you doing bounds checking for your array? Try the 
> -boundscheck=off compiler flag. (That may be new in 2.066. 
> Otherwise, try -noboundscheck.)

I had it set through dub's "buildOptions". Will there be a @nogc 
or @noheap flag in 2.066? I read some forum posts about it but 
can't seem to find whether it will be part of the next release.