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 vararg5;
import tango.core.Vararg;
extern(C) int printf(char*, ...);
void func(...)
{
    char[] str = va_arg!(char[])(_argptr);
    {printf("%.*s\n", str.length, str.ptr);}
}
void main()
{
    char[] str = "hello";
    func(str);
}