why are types mismatch?

[deadalnix]

On Tuesday, 1 October 2013 at 18:38:33 UTC, Roman wrote:
>> Can you paste the output of your code so we can help you more 
>> easily ?
>
> int(int i) != int function(int)
> int function(int i) pure nothrow @safe != int function(int)
> 2
> 4
>
> So, why 1st case incorrect?

The first case is a bug to me. Can you fill it in 
http://d.puremagic.com/issues/ please ? The second is expected.

What you should do is test via is(typeof(...)) : function_type). 
The : test for implicit conversion, and int function(int i) pure 
nothrow @safe convert implicitly to int function(int) .