Wrong lowering for a[b][c]++

[Andrei Alexandrescu]

On 3/22/12 9:32 AM, H. S. Teoh wrote:
> On Thu, Mar 22, 2012 at 11:01:35AM +0100, Andrej Mitrovic wrote:
>> On 3/21/12, H. S. Teoh<hsteoh at quickfur.ath.cx>  wrote:
>>> Sorry, I was thinking in terms of my AA implementation which is done
>>> using a struct with operator overloading. I should've checked what the
>>> behaviour of the current built-in AAs are before posting. :-P
>>
>> Well in that case isn't it a necessity to keep compatibility with the
>> old implementation? Do we really have to break user-code again?
>
> Yes we have to keep compatibility. But as some have pointed out, this
> works:
>
> 	int[string][int] map;
> 	map[20]["abc"]++;	// sets map[20]["abc"] to 1
>
> Looking at druntime code, I see that in aaA.d there's _aaGetX (which
> creates a new entry if it doesn't already exist) and _aaGetRvalueX
> (doesn't create new entry).  Which look like the equivalents of
> opIndexCreate and opIndex.
>
> The problem is that the language doesn't currently support the former in
> user-defined structs; so this *will* break compatibility.

This is a bug in the language that requires fixing.

Andrei