src/test/compile-fail/borrowck-mutate-in-guard.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 enum Enum<'a> {
  12     A(&'a isize),
  13     B(bool),
  14 }
  15
  16 fn foo() -> isize {
  17     let mut n = 42;
  18     let mut x = Enum::A(&mut n);
  19     match x {
  20         Enum::A(_) if { x = Enum::B(false); false } => 1,
  21         //~^ ERROR cannot assign in a pattern guard
  22         Enum::A(_) if { let y = &mut x; *y = Enum::B(false); false } => 1,
  23         //~^ ERROR cannot mutably borrow in a pattern guard
  24         //~^^ ERROR cannot assign in a pattern guard
  25         Enum::A(p) => *p,
  26         Enum::B(_) => 2,
  27     }
  28 }
  29
  30 fn main() {
  31     foo();
  32 }