]>
Commit | Line | Data |
---|---|---|
f20569fa | 1 | #![feature(stmt_expr_attributes)] |
f2b60f7d | 2 | #![allow(clippy::let_unit_value, invalid_value)] |
f20569fa | 3 | |
353b0b11 FG |
4 | use std::mem::MaybeUninit; |
5 | ||
6 | union MyOwnMaybeUninit { | |
7 | value: u8, | |
8 | uninit: (), | |
9 | } | |
f20569fa XL |
10 | |
11 | fn main() { | |
12 | let _: usize = unsafe { MaybeUninit::uninit().assume_init() }; | |
13 | ||
353b0b11 | 14 | // This is OK, because ZSTs do not contain data. |
f20569fa XL |
15 | let _: () = unsafe { MaybeUninit::uninit().assume_init() }; |
16 | ||
17 | // This is OK, because `MaybeUninit` allows uninitialized data. | |
18 | let _: MaybeUninit<usize> = unsafe { MaybeUninit::uninit().assume_init() }; | |
19 | ||
49aad941 | 20 | // This is OK, because all constituent types are uninit-compatible. |
f20569fa XL |
21 | let _: (MaybeUninit<usize>, MaybeUninit<bool>) = unsafe { MaybeUninit::uninit().assume_init() }; |
22 | ||
49aad941 | 23 | // This is OK, because all constituent types are uninit-compatible. |
f20569fa | 24 | let _: (MaybeUninit<usize>, [MaybeUninit<bool>; 2]) = unsafe { MaybeUninit::uninit().assume_init() }; |
cdc7bbd5 | 25 | |
353b0b11 FG |
26 | // This is OK, because our own MaybeUninit is just as fine as the one from core. |
27 | let _: MyOwnMaybeUninit = unsafe { MaybeUninit::uninit().assume_init() }; | |
28 | ||
29 | // This is OK, because empty arrays don't contain data. | |
30 | let _: [u8; 0] = unsafe { MaybeUninit::uninit().assume_init() }; | |
31 | ||
cdc7bbd5 | 32 | // Was a false negative. |
353b0b11 FG |
33 | let _: usize = unsafe { MaybeUninit::uninit().assume_init() }; |
34 | ||
35 | polymorphic::<()>(); | |
36 | polymorphic_maybe_uninit_array::<10>(); | |
37 | polymorphic_maybe_uninit::<u8>(); | |
38 | ||
39 | fn polymorphic<T>() { | |
40 | // We are conservative around polymorphic types. | |
41 | let _: T = unsafe { MaybeUninit::uninit().assume_init() }; | |
42 | } | |
43 | ||
44 | fn polymorphic_maybe_uninit_array<const N: usize>() { | |
45 | // While the type is polymorphic, MaybeUninit<u8> is not. | |
46 | let _: [MaybeUninit<u8>; N] = unsafe { MaybeUninit::uninit().assume_init() }; | |
47 | } | |
48 | ||
49 | fn polymorphic_maybe_uninit<T>() { | |
50 | // The entire type is polymorphic, but it's wrapped in a MaybeUninit. | |
51 | let _: MaybeUninit<T> = unsafe { MaybeUninit::uninit().assume_init() }; | |
52 | } | |
f20569fa | 53 | } |