DIP66 - Multiple alias this

[IgorStepanov via Digitalmars-d]

On Saturday, 11 October 2014 at 00:00:48 UTC, Walter Bright wrote:
> On 10/10/2014 4:23 PM, IgorStepanov wrote:
>> On Friday, 10 October 2014 at 22:50:25 UTC, Walter Bright 
>> wrote:
>>> must be an error, even if one of C.a() or C.b() might be a 
>>> "better" match.
>>> This is how things work for template mixins and imports.
>> So it is.
>
> Good!
>
> The same rule applies for overloading.

I've implemented overloading:
https://github.com/D-Programming-Language/dmd/pull/3998/files#diff-17b22eae29e74ce6ec29037438b5031cR2136

Please, tell me, what changes should I make to the DIP as a 
result of yesterday's discussions.
And please, tell your opinion about "is" issue:

class A
{
    int i;
    alias i this;
}

class B
{
    int i;
    alias i this;
}

class C
{
    A a;
    B b;
    alias a this;
    alias b this;
}

void foo(T)(T arg) if(is(T : int))
{
    ...
}

foo(C()); //Should it pass or not?