// Copyright 2014 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use core::nonzero::NonZero;
use std::u32;

#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct NodeIndex {
    index: NonZero<u32>,
}

impl NodeIndex {
    pub fn new(value: usize) -> NodeIndex {
        assert!(value < (u32::MAX as usize));
        NodeIndex { index: NonZero::new((value as u32) + 1).unwrap() }
    }

    pub fn get(self) -> usize {
        (self.index.get() - 1) as usize
    }
}

// Copyright 2014 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use core::nonzero::NonZero;
use std::u32;

#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct NodeIndex {
    index: NonZero<u32>,
}

impl NodeIndex {
    pub fn new(value: usize) -> NodeIndex {
        assert!(value < (u32::MAX as usize));
        unsafe { NodeIndex { index: NonZero::new_unchecked((value as u32) + 1) } }
    }

    pub fn get(self) -> usize {
        (self.index.get() - 1) as usize
    }
}

--- 
+++ 
@@ -19,7 +19,7 @@
 impl NodeIndex {
     pub fn new(value: usize) -> NodeIndex {
         assert!(value < (u32::MAX as usize));
-        unsafe { NodeIndex { index: NonZero::new_unchecked((value as u32) + 1) } }
+        NodeIndex { index: NonZero::new((value as u32) + 1).unwrap() }
     }
 
     pub fn get(self) -> usize {
Use checked NonZero constructor in obligation forest NodeIndex

… to remove an `unsafe` block.
