rust/src/test/compile-fail/static-mut-requires-unsafe.rs

// Copyright 2013 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.

static mut a: isize = 3;

fn main() {
    a += 3;         //~ ERROR: requires unsafe
    a = 4;          //~ ERROR: requires unsafe
    let _b = a;     //~ ERROR: requires unsafe
}