// 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 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. struct Foo { x: int, y: int, } impl Index for Foo { fn index<'a>(&'a self, z: &String) -> &'a int { if z.as_slice() == "x" { &self.x } else { &self.y } } } impl IndexMut for Foo { fn index_mut<'a>(&'a mut self, z: &String) -> &'a mut int { if z.as_slice() == "x" { &mut self.x } else { &mut self.y } } } struct Bar { x: int, } impl Index for Bar { fn index<'a>(&'a self, z: &int) -> &'a int { &self.x } } fn main() { let mut f = Foo { x: 1, y: 2, }; let mut s = "hello".to_string(); let rs = &mut s; println!("{}", f[s]); //~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable f[s] = 10; //~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable let s = Bar { x: 1, }; s[2] = 20; //~^ ERROR cannot assign to immutable dereference (dereference is implicit, due to indexing) }