`f64::round` produces Illegal Instruction on `arm-unknown-linux-gnueabihf`

[reitermarkus]

I am cross-compiling for a Raspberry Pi Zero W (arm-unknown-linux-gnueabihf), and I am experiencing a strange issue when using f64::round, which leads to an “Illegal Instruction”. Here are some minimal examples:

1. Illegal Instruction at line 4

fn main() {
  let v: f64 = 0.0;
  println!("works: {:?}", v);
  println!("fails: {:?}", (v * 10.0).round());
}

2. No Illegal Instruction

fn main() {
  let v: f64 = 0.0;
  println!("works: {:?}", v.round());
  println!("works: {:?}", (v * 10.0).round());
}

3. No Illegal Instruction

fn main() {
  let v: f64 = 0.0;
  println!("works: {:?}", v);
  println!("works: {:?}", (v * 1.0).round());
}

Apparently, the Raspberry Pi Zero W is actually a arm-unknown-linux-gnueabi. With arm-unknown-linux-gnueabi, I am experiencing the same behaviour, except instead of crashing with an “Illegal Instruction” it produces NaN.

---

References https://users.rust-lang.org/t/f64-round-produces-illegal-instruction-on-arm-unknown-linux-gnueabihf/30798.

[reitermarkus]

I wasn't using the latest nightly because of clippy, this seems to be fixed.