src/test/ui/lint/uninitialized-zeroed.rs

   1 // This test checks that calling `mem::{uninitialized,zeroed}` with certain types results
   2 // in a lint.
   3
   4 #![feature(never_type, rustc_attrs)]
   5 #![allow(deprecated)]
   6 #![deny(invalid_value)]
   7
   8 use std::mem::{self, MaybeUninit};
   9 use std::ptr::NonNull;
  10 use std::num::NonZeroU32;
  11
  12 enum Void {}
  13
  14 struct Ref(&'static i32);
  15 struct RefPair((&'static i32, i32));
  16
  17 struct Wrap<T> { wrapped: T }
  18 enum WrapEnum<T> { Wrapped(T) }
  19
  20 #[rustc_layout_scalar_valid_range_start(0)]
  21 #[rustc_layout_scalar_valid_range_end(128)]
  22 #[repr(transparent)]
  23 pub(crate) struct NonBig(u64);
  24
  25 /// A two-variant enum, thus needs a tag and may not remain uninitialized.
  26 enum Fruit {
  27     Apple,
  28     Banana,
  29 }
  30
  31 /// Looks like two variants but really only has one.
  32 enum OneFruit {
  33     Apple(!),
  34     Banana,
  35 }
  36
  37 #[allow(unused)]
  38 fn generic<T: 'static>() {
  39     unsafe {
  40         let _val: &'static T = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  41         let _val: &'static T = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  42
  43         let _val: Wrap<&'static T> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  44         let _val: Wrap<&'static T> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  45     }
  46 }
  47
  48 fn main() {
  49     unsafe {
  50         // Things that cannot even be zero.
  51         let _val: ! = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  52         let _val: ! = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  53
  54         let _val: (i32, !) = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  55         let _val: (i32, !) = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  56
  57         let _val: Void = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  58         let _val: Void = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  59
  60         let _val: &'static i32 = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  61         let _val: &'static i32 = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  62
  63         let _val: Ref = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  64         let _val: Ref = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  65
  66         let _val: fn() = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  67         let _val: fn() = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  68
  69         let _val: Wrap<fn()> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  70         let _val: Wrap<fn()> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  71
  72         let _val: WrapEnum<fn()> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  73         let _val: WrapEnum<fn()> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  74
  75         let _val: Wrap<(RefPair, i32)> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  76         let _val: Wrap<(RefPair, i32)> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  77
  78         let _val: NonNull<i32> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  79         let _val: NonNull<i32> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  80
  81         let _val: *const dyn Send = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  82         let _val: *const dyn Send = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  83
  84         let _val: [fn(); 2] = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  85         let _val: [fn(); 2] = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  86
  87         // Things that can be zero, but not uninit.
  88         let _val: bool = mem::zeroed();
  89         let _val: bool = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  90
  91         let _val: Wrap<char> = mem::zeroed();
  92         let _val: Wrap<char> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  93
  94         let _val: NonBig = mem::zeroed();
  95         let _val: NonBig = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  96
  97         let _val: Fruit = mem::zeroed();
  98         let _val: Fruit = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  99
 100         let _val: [bool; 2] = mem::zeroed();
 101         let _val: [bool; 2] = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
 102
 103         // Transmute-from-0
 104         let _val: &'static i32 = mem::transmute(0usize); //~ ERROR: does not permit zero-initialization
 105         let _val: &'static [i32] = mem::transmute((0usize, 0usize)); //~ ERROR: does not permit zero-initialization
 106         let _val: NonZeroU32 = mem::transmute(0); //~ ERROR: does not permit zero-initialization
 107
 108         // `MaybeUninit` cases
 109         let _val: NonNull<i32> = MaybeUninit::zeroed().assume_init(); //~ ERROR: does not permit zero-initialization
 110         let _val: NonNull<i32> = MaybeUninit::uninit().assume_init(); //~ ERROR: does not permit being left uninitialized
 111         let _val: bool = MaybeUninit::uninit().assume_init(); //~ ERROR: does not permit being left uninitialized
 112
 113         // Some more types that should work just fine.
 114         let _val: Option<&'static i32> = mem::zeroed();
 115         let _val: Option<fn()> = mem::zeroed();
 116         let _val: MaybeUninit<&'static i32> = mem::zeroed();
 117         let _val: i32 = mem::zeroed();
 118         let _val: bool = MaybeUninit::zeroed().assume_init();
 119         let _val: [bool; 0] = MaybeUninit::uninit().assume_init();
 120         let _val: [!; 0] = MaybeUninit::zeroed().assume_init();
 121         // Some things that happen to work due to rustc implementation details,
 122         // but are not guaranteed to keep working.
 123         let _val: i32 = mem::uninitialized();
 124         let _val: OneFruit = mem::uninitialized();
 125     }
 126 }