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 strings1;
extern(C) int printf(char*, ...);
void f(char[11] buffer)
{
    printf("%.*s\n", buffer.length, buffer.ptr);
}

void main()
{
    char[11] buffer;
    char[] hello = "hello world";
    {buffer[] = hello[];}
    {f(buffer);}
    {f("eleven char");}
}