src/test/run-pass/panic-uninitialized-zeroed.rs

   1 // Copyright 2018 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 // This test checks that instantiating an uninhabited type via `mem::{uninitialized,zeroed}` results
  12 // in a runtime panic.
  13
  14 #![feature(never_type)]
  15
  16 use std::{mem, panic};
  17
  18 struct Foo {
  19     x: u8,
  20     y: !,
  21 }
  22
  23 fn main() {
  24     unsafe {
  25         assert_eq!(
  26             panic::catch_unwind(|| {
  27                 mem::uninitialized::<!>()
  28             }).err().and_then(|a| a.downcast_ref::<String>().map(|s| {
  29                 s == "Attempted to instantiate uninhabited type ! using mem::uninitialized"
  30             })),
  31             Some(true)
  32         );
  33
  34         assert_eq!(
  35             panic::catch_unwind(|| {
  36                 mem::zeroed::<!>()
  37             }).err().and_then(|a| a.downcast_ref::<String>().map(|s| {
  38                 s == "Attempted to instantiate uninhabited type ! using mem::zeroed"
  39             })),
  40             Some(true)
  41         );
  42
  43         assert_eq!(
  44             panic::catch_unwind(|| {
  45                 mem::uninitialized::<Foo>()
  46             }).err().and_then(|a| a.downcast_ref::<String>().map(|s| {
  47                 s == "Attempted to instantiate uninhabited type Foo using mem::uninitialized"
  48             })),
  49             Some(true)
  50         );
  51
  52         assert_eq!(
  53             panic::catch_unwind(|| {
  54                 mem::zeroed::<Foo>()
  55             }).err().and_then(|a| a.downcast_ref::<String>().map(|s| {
  56                 s == "Attempted to instantiate uninhabited type Foo using mem::zeroed"
  57             })),
  58             Some(true)
  59         );
  60     }
  61 }