int a @if(0); failed to compile

Given below code:
```
fn void main()
{
    int $a=0;
    if($a){} //ok
    int a @if(!$a);//ok
    int a @if($a);// Error: Expected a boolean compile time constant value
    int a @if((bool)$a);//ok
}
```
May I ask is this the intended design? 