Casting u128::MAX to f32 is undefined #41799
Description
Given this code (playpen):
#![feature(i128_type,i128)]
fn cast(src: f32) -> Result<u128, &'static str> {
use std::{u128, f32};
Err(if src != src {
"NaN"
} else if src < u128::MIN as f32 {
"Underflow"
} else if src > u128::MAX as f32 {
"Overflow"
} else {
return Ok(src as u128);
})
}
fn main() {
let f = 2742605.0f32;
println!("{:?}", cast(f));
}It should print Ok(2742605). In release mode, that happens, but in debug mode, it prints Err("Overflow").
The value is mostly irrelevant, it would also work for 42.0.