src/test/compile-fail/unused-result.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 #![allow(dead_code)]
  12 #![deny(unused_results, unused_must_use)]
  13 //~^ NOTE: lint level defined here
  14 //~| NOTE: lint level defined here
  15
  16 #[must_use]
  17 enum MustUse { Test }
  18
  19 #[must_use = "some message"]
  20 enum MustUseMsg { Test2 }
  21
  22 fn foo<T>() -> T { panic!() }
  23
  24 fn bar() -> isize { return foo::<isize>(); }
  25 fn baz() -> MustUse { return foo::<MustUse>(); }
  26 fn qux() -> MustUseMsg { return foo::<MustUseMsg>(); }
  27
  28 #[allow(unused_results)]
  29 fn test() {
  30     foo::<isize>();
  31     foo::<MustUse>(); //~ ERROR: unused `MustUse` which must be used
  32     foo::<MustUseMsg>(); //~ ERROR: unused `MustUseMsg` which must be used
  33     //~^ NOTE: some message
  34 }
  35
  36 #[allow(unused_results, unused_must_use)]
  37 fn test2() {
  38     foo::<isize>();
  39     foo::<MustUse>();
  40     foo::<MustUseMsg>();
  41 }
  42
  43 fn main() {
  44     foo::<isize>(); //~ ERROR: unused result
  45     foo::<MustUse>(); //~ ERROR: unused `MustUse` which must be used
  46     foo::<MustUseMsg>(); //~ ERROR: unused `MustUseMsg` which must be used
  47     //~^ NOTE: some message
  48
  49     let _ = foo::<isize>();
  50     let _ = foo::<MustUse>();
  51     let _ = foo::<MustUseMsg>();
  52 }