Detecting inadvertent use of integer division

[Sean Kelly]

Don Wrote:

> Walter Bright wrote:
> > Don wrote:
> >>
> >> (This means that double y = int_val / 1;  is OK, and also:
> >>  double z = 90/3; would be OK. An alternative rule would be:
> >> "If an integer expression involves integer divison, that expression 
> >> cannot be implicitly cast to a floating-point type").
> > 
> > This is kinda complicated if one has, say:
> > 
> >     double z = x/y + 3;
> 
> Integer expressions remain inexact until there's a cast.
> 
> (It's very simple to implement, you just use the integer range code, 
> adding an 'inexact' flag. Division sets the flag, casts clear the flag, 
> everything else just propagates it if a unary operation, or ORs the two 
> flags if a binary operation).

Assuming it really is this easy, I'd love to see the change.  I've run into this bug countless times reviewing code, and it can be a tricky one to find.  I tend to be pretty particular about always appending the ".0" for literals involved in floating-point assignments for this reason.