BitArray - incomplete implementation?

[Laeeth Isharc via Digitalmars-d-learn]

> Yes, that error is caused by a bug of 
> BitArray(https://issues.dlang.org/show_bug.cgi?id=13806). 
> Having "init" function broke template constraints of 
> "chain"(and must break dozen of other templates).
>
> pragma(msg, ElementType!(BitArray[])) // prints 'pure nothrow 
> void(bool[] ba)' - ElementType uses "init" property to 
> determine types.


Thanks for this.  If I recompile phobos with the pull request 
(having edited out the init property entirely) then the code 
mostly works.

However, I still can't use join, joiner, or chain on two 
BitArrays.  Eg
auto x=joiner(a,b).array;

I can chain two arrays of BitArrays, but not join or joiner them.

If this is what ought to happen, why?