Make == for associative arrays test for equality, not identity. _aaEq was added to runtime/internal/aaA.d which forwards to TypeInfo_AssociativeArray.equals in genobj.d. On the codegen side, DtoAAEquals was added to gen/aa.cpp and is called from EqualExp::toElem in gen/toir.cpp. I assume that the frontend will produce an error if == is used on associative arrays of different type. This fixes DMD bug 1429.

module bug29;
extern(C) int printf(char*, ...);

void main()
{
    int[] arr16 = new int[4];
    {
        void[] arr = arr16;
        {
            printf("%lu\n", arr.length);
            {
                assert(arr.length == 16);
            }
        }
    }
}