u8(255.0) yields Overflow

[federicomenaquintero]

use cast::u8;

fn main() {
    println!("{:?}", u8(255.0)); // yields Overflow
}

It should be Ok(255), of course 😃

[oherrala]

This conversion error happens on line 299 of lib.rs where the transmutes returns a value 254.99999999999997 for max and then on line 301 src is compared to max as 255 > 254.99999999999997 which of course is true and the whole cast functions return Error::Overflow on line 303.

cast.rs/src/lib.rs

Lines 293 to 304 in cd85b66

	} else if {
	// we subtract 1 ULP (unit of least precision) here because some
	// lossy conversions like `u64::MAX as f64` round *up* and we want
	// to avoid this evaluating to false in that case
	use core::mem::transmute;
	let max = unsafe {
	transmute::<_, $src>(transmute::<_, $usrc>($dst::MAX as $src) - 1)
	};
	src > max
	} {
	Error::Overflow
	} else if $dst::MIN == 0 {

This bug was introduced in 3f0bf8b to fix issue #15.