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[Stanislav Blinov]

On Thursday, 23 January 2014 at 16:40:49 UTC, Frustrated wrote:
> Yes, I that is what I tried initially but the error was  due to
> that static if.
>
> Not sure why
>
> but
>
> 		static if (is(T : A))
> 		{
>                       ...
> 		}
> 		static assert(0, "error");
>
>
> doesn't work as the assert is called no matter what. Initially I
> forgot to return the value after changing the code but that
> doesn't matter.

As it should be. That static assert gets compiled 
unconditionally, thus asserts.

> Had to change it to
>
>
> 		static if (is(T : A))
> 		{
>                       ...
>                       return ...;
> 		} else
> 		   static assert(0, "error");
>                  return null;
>
> I guess because return is not "static" in some sense.

else is the correct thing to do here. Otherwise you could have 
put a runtime assert(0) there, i.e.:

static if (is(T : A))
{
     return "All is good";
}
assert(0, "This should never happen!");