No polymorphism?

[Dgame via Digitalmars-d-learn]

On Monday, 24 July 2017 at 18:15:20 UTC, Steven Schveighoffer 
wrote:
> On 7/24/17 1:29 PM, Dgame wrote:
>
>> Why isn't the compiler able to deduce S[] => I[]? Or is it 
>> just me?
>> I've tried dmd 2.075
>
> I know you got the explanation already, but just in case you 
> actually need to call something like test1 but only have an S[]:
>
> test1(ss.map!((I i) => i).array)
>
> -Steve

Thanks.