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

   1 // ignore-tidy-linelength
   2 // This test checks that calling `mem::{uninitialized,zeroed}` with certain types results
   3 // in a lint.
   4
   5 #![feature(never_type, rustc_attrs)]
   6 #![allow(deprecated)]
   7 #![deny(invalid_value)]
   8
   9 use std::mem::{self, MaybeUninit};
  10 use std::ptr::NonNull;
  11 use std::num::NonZeroU32;
  12
  13 enum Void {}
  14
  15 struct Ref(&'static i32);
  16 struct RefPair((&'static i32, i32));
  17
  18 struct Wrap<T> { wrapped: T }
  19 enum WrapEnum<T> { Wrapped(T) }
  20
  21 #[rustc_layout_scalar_valid_range_start(0)]
  22 #[rustc_layout_scalar_valid_range_end(128)]
  23 #[repr(transparent)]
  24 pub(crate) struct NonBig(u64);
  25
  26 #[allow(unused)]
  27 fn generic<T: 'static>() {
  28     unsafe {
  29         let _val: &'static T = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  30         let _val: &'static T = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  31
  32         let _val: Wrap<&'static T> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  33         let _val: Wrap<&'static T> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  34     }
  35 }
  36
  37 fn main() {
  38     unsafe {
  39         // Things that cannot even be zero.
  40         let _val: ! = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  41         let _val: ! = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  42
  43         let _val: (i32, !) = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  44         let _val: (i32, !) = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  45
  46         let _val: Void = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  47         let _val: Void = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  48
  49         let _val: &'static i32 = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  50         let _val: &'static i32 = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  51
  52         let _val: Ref = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  53         let _val: Ref = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  54
  55         let _val: fn() = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  56         let _val: fn() = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  57
  58         let _val: Wrap<fn()> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  59         let _val: Wrap<fn()> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  60
  61         let _val: WrapEnum<fn()> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  62         let _val: WrapEnum<fn()> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  63
  64         let _val: Wrap<(RefPair, i32)> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  65         let _val: Wrap<(RefPair, i32)> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  66
  67         let _val: NonNull<i32> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  68         let _val: NonNull<i32> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  69
  70         let _val: *const dyn Send = mem::zeroed(); //~ ERROR: does not permit zero-initialization
  71         let _val: *const dyn Send = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  72
  73         // Things that can be zero, but not uninit.
  74         let _val: bool = mem::zeroed();
  75         let _val: bool = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  76
  77         let _val: Wrap<char> = mem::zeroed();
  78         let _val: Wrap<char> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  79
  80         let _val: NonBig = mem::zeroed();
  81         let _val: NonBig = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
  82
  83         // Transmute-from-0
  84         let _val: &'static i32 = mem::transmute(0usize); //~ ERROR: does not permit zero-initialization
  85         let _val: &'static [i32] = mem::transmute((0usize, 0usize)); //~ ERROR: does not permit zero-initialization
  86         let _val: NonZeroU32 = mem::transmute(0); //~ ERROR: does not permit zero-initialization
  87
  88         // `MaybeUninit` cases
  89         let _val: NonNull<i32> = MaybeUninit::zeroed().assume_init(); //~ ERROR: does not permit zero-initialization
  90         let _val: NonNull<i32> = MaybeUninit::uninit().assume_init(); //~ ERROR: does not permit being left uninitialized
  91         let _val: bool = MaybeUninit::uninit().assume_init(); //~ ERROR: does not permit being left uninitialized
  92
  93         // Some more types that should work just fine.
  94         let _val: Option<&'static i32> = mem::zeroed();
  95         let _val: Option<fn()> = mem::zeroed();
  96         let _val: MaybeUninit<&'static i32> = mem::zeroed();
  97         let _val: i32 = mem::zeroed();
  98         let _val: bool = MaybeUninit::zeroed().assume_init();
  99     }
 100 }