src/test/compile-fail/uninhabited-patterns.rs

   1 // Copyright 2012 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 #![feature(box_patterns)]
  12 #![feature(slice_patterns)]
  13 #![feature(box_syntax)]
  14 #![feature(never_type)]
  15 #![deny(unreachable_patterns)]
  16
  17 mod foo {
  18     pub struct SecretlyEmpty {
  19         _priv: !,
  20     }
  21 }
  22
  23 struct NotSoSecretlyEmpty {
  24     _priv: !,
  25 }
  26
  27 fn foo() -> Option<NotSoSecretlyEmpty> {
  28     None
  29 }
  30
  31 fn main() {
  32     let x: &[!] = &[];
  33
  34     match x {
  35         &[]   => (),
  36         &[..] => (),    //~ ERROR unreachable pattern
  37     };
  38
  39     let x: Result<Box<NotSoSecretlyEmpty>, &[Result<!, !>]> = Err(&[]);
  40     match x {
  41         Ok(box _) => (),    //~ ERROR unreachable pattern
  42         Err(&[]) => (),
  43         Err(&[..]) => (),   //~ ERROR unreachable pattern
  44     }
  45
  46     let x: Result<foo::SecretlyEmpty, Result<NotSoSecretlyEmpty, u32>> = Err(Err(123));
  47     match x {
  48         Ok(_y) => (),
  49         Err(Err(_y)) => (),
  50         Err(Ok(_y)) => (),  //~ ERROR unreachable pattern
  51     }
  52
  53     while let Some(_y) = foo() {
  54         //~^ ERROR unreachable pattern
  55     }
  56 }
  57