rust/src/test/compile-fail/indexing-requires-a-uint.rs
Alex Crichton 46abacfdfe rustc: Require that vector indices are uints
This commit tightens up the restriction on types used to index slices to require
exactly `uint` indices. Previously any integral type was accepted, but this
leads to a few subtle problems:

  * 64-bit indices don't make much sense on 32-bit systems
  * Signed indices for slices used as negative indexing isn't implemented

This was discussed at the recent work week, and also has some discussion on
issue #10453.

Closes #10453
2014-04-02 15:56:31 -07:00

26 lines
874 B
Rust

// 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.
// Make sure that indexing an array is only valid with a `uint`, not any other
// integral type.
fn main() {
fn bar<T>(_: T) {}
[0][0u8]; //~ ERROR: mismatched types
[0][0]; // should infer to be a uint
let i = 0; // i is an IntVar
[0][i]; // i should be locked to uint
bar::<int>(i); // i should not be re-coerced back to an int
//~^ ERROR: mismatched types
}