GC scan for pointers

[thedeemon via Digitalmars-d-learn]

On Wednesday, 9 March 2016 at 15:14:02 UTC, Gerald Jansen wrote:
> I've studied [1] and [2] but don't understand everything there. 
> Hence these dumb questions:
>
> Given
>
>   enum n = 100_000_000; // some big number
>   auto a = new ulong[](n);
>   auto b = new char[8][](n);
>   struct S { ulong x; char[8] y; }
>   auto c = new S[](n);
>
> will the large memory blocks allocated for a, b and/or c 
> actually be scanned for pointers to GC-allocated memory during 
> a garbage collection? If so, why?

I've just tested it with my GC tracker ( 
https://bitbucket.org/infognition/dstuff ), all 3 allocations go 
with flags APPENDABLE | NO_SCAN which means these blocks will not 
be scanned.

But if you define S as
struct S { ulong x; char[] y; }
so there is some pointer inside, then it gets allocated with just 
APPENDABLE flag, i.e. it will be scanned then.