GC and void[N] in struct

[vit]

On Monday, 6 August 2018 at 18:28:11 UTC, Steven Schveighoffer 
wrote:
> On 8/6/18 2:22 PM, vit wrote:
>> Hello,
>> I have this struct:
>> 
>> struct S{
>>      uint kind;
>>      void[N] data_;
>
> define "N"
>
>> 
>> }
>> 
>> Instances of struct S are allocated by standard GC new and 
>> S.data_ can contain pointers/ranges to GC allocated data.
>> If is GC disabled then  program run fine. But when is GC 
>> enabled then it fail randomly.
>
> how does it fail?
>
> -Steve


private auto sizeOf(T)(){return T.sizeof;}

struct ExprImpl(Ts...){
     enum N = max(staticMap!(sizeOf, Ts));

     invariant(kind_ != 0);
     uint kind_ = 0;
     void[N] data_;

     this(T)(auto ref T x){/+emplace T to data_ and change kind_ 
to something != 0+/}
}

Ts == structs



data change without triggering invariant after allocation in 
other part of program.