RFC: Value range propagation for if-else

["Nordlöw" via Digitalmars-d]

> I think that unfortunately this currently can't work, you can't 
> tell the range of the input value like that. I have explained 
> why in one of my posts in this thread. Please try to explain me 
> why I'm wrong.

I'm currently merely talking about possibilities in this case, so 
I cannot currently prove you wronge ;) To me it seem like an 
unneccessary limitation that valueRanges aren't propagated to 
function call arguments provided that the function source is 
known at compile time. And it doesn't sound to me like enabling 
this in DMD would be such a great task either.