DIP 1017--Add Bottom Type--Community Review Round 1

[Petar]

On Friday, 10 August 2018 at 07:19:02 UTC, Andrea Fontana wrote:
> On Friday, 10 August 2018 at 07:01:09 UTC, Petar Kirov 
> [ZombineDev] wrote:
>>
>> `is(T == U)` evaluates to true iff `T` is exactly `U`. `is(T : 
>> U)` tests if `T` is a subtype of (can be implicitly converted 
>> to) `U` [0]. So we have:
>>
>> `is(typeof(assert(0)) == T)` is false, unless `T` is 
>> `typeof(assert(0))`
>> `is(typeof(assert(0)) : T)` is always true (as bottom is 
>> implicitly convertible to any other type, including itself).
>>
>> [0]: https://dlang.org/spec/expression#is_expression
>
> So if I need to write something like:
>
> void callback(alias T)() if(is(ReturnType!T ==  int))
> {
> }
>
> I have to change it to:
> void callback(alias T)() if(is(ReturnType!T ==  int) || 
> is(ReturnType!T == typeof(assert(0)))
> {
> }
>
> ?

No. That's the point - you don't have to change anything.