constants are not constant due to ptr->int casts

[thestinger]

fn main() {
    const X: u32 = 1;
    const Y: uint = &X as *const u32 as uint;
    println!("{}", Y);
}

Fixing this requires backwards incompatible changes to constant expressions. At a minimum, casts from pointers to integers need to be forbidden. It's possible that there are other issues.

[jdm]

Can you elaborate on the problem here?

[thestinger]

@jdm: If it's not obvious from the code, compile and run it several times. The value of Y is determined at runtime so it's not a valid constant expression. The const type was supposed to be distinct from static by being a valid constant expression in every case but it is not.

[arielb1]

We really shouldn't be allowing pointer -> uint conversions in constexprs.