Should operators on literals delay range check?

[Shachar]

def var : S8 = 0 - 128;

Should it not compile, because 128 is not a valid number for the expected type S8? In which case, the code needs to be written as:
def var : S8 = expect!S16(0 - 128);

Or should the check for range be delayed? How about:

def var : S8 = 128 - 256;?