Unusual template specialisation behavior

[Christopher Wright]

Matthias Walter wrote:
> Christopher Wright Wrote:
> 
>> Matthias Walter wrote:
>>> Hello guys,
>>>
>>> Here's a (minimal) code snippet for my problem:
>>>
>>> | struct Expression (R, E) { }
>>> | 
>>> | struct ResolveReference (T)
>>> | {
>>> |     alias T reference_type;
>>> | }
>>> | 
>>> | struct ResolveReference (T : Expression !(R, E))
>> The compiler should have caught this, I think. You have R and E, but 
>> they aren't defined. They default to int (which is why you saw that 
>> behavior), but not being defined, they should be a compile-time error.
>>
>> The proper way to do this, unfortunately, involves static if rather than 
>> overloading. At least if you want your users to supply a single argument 
>> in all cases.
> 
> Thanks for that hint. How would such a static if look like?

template ResolveReference (T) {
    static if (is (T == Expression!(R, E))) {
    // or `static if (is (T == Expression!(R, E), R, E)) {`
       alias T* ResolveReference;
    } else {
       alias T ResolveReference;
    }
}

Except that doesn't work, right now. There's a bug listed for it.