// Copyright 2012 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. pub trait NumCast: Sized { fn from(i: i32) -> Option; } pub trait NumExt: PartialEq + PartialOrd + NumCast {} impl NumExt for f32 {} impl NumCast for f32 { fn from(i: i32) -> Option { Some(i as f32) } } fn num_eq_one(n: T) { println!("{}", n == NumCast::from(1).unwrap()) } pub fn main() { num_eq_one(1f32); // you need to actually use the function to trigger the ICE }