diff options
Diffstat (limited to 'vendor/bytemuck/src/no_uninit.rs')
| -rw-r--r-- | vendor/bytemuck/src/no_uninit.rs | 80 |
1 files changed, 0 insertions, 80 deletions
diff --git a/vendor/bytemuck/src/no_uninit.rs b/vendor/bytemuck/src/no_uninit.rs deleted file mode 100644 index 5fda0c9..0000000 --- a/vendor/bytemuck/src/no_uninit.rs +++ /dev/null @@ -1,80 +0,0 @@ -use crate::Pod; -use core::num::{ - NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize, - NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize, -}; - -/// Marker trait for "plain old data" types with no uninit (or padding) bytes. -/// -/// The requirements for this is very similar to [`Pod`], -/// except that it doesn't require that all bit patterns of the type are valid, -/// i.e. it does not require the type to be [`Zeroable`][crate::Zeroable]. -/// This limits what you can do with a type of this kind, but also broadens the -/// included types to things like C-style enums. Notably, you can only cast from -/// *immutable* references to a [`NoUninit`] type into *immutable* references of -/// any other type, no casting of mutable references or mutable references to -/// slices etc. -/// -/// [`Pod`] is a subset of [`NoUninit`], meaning that any `T: Pod` is also -/// [`NoUninit`] but any `T: NoUninit` is not necessarily [`Pod`]. If possible, -/// prefer implementing [`Pod`] directly. To get more [`Pod`]-like functionality -/// for a type that is only [`NoUninit`], consider also implementing -/// [`CheckedBitPattern`][crate::CheckedBitPattern]. -/// -/// # Derive -/// -/// A `#[derive(NoUninit)]` macro is provided under the `derive` feature flag -/// which will automatically validate the requirements of this trait and -/// implement the trait for you for both enums and structs. This is the -/// recommended method for implementing the trait, however it's also possible to -/// do manually. If you implement it manually, you *must* carefully follow the -/// below safety rules. -/// -/// # Safety -/// -/// The same as [`Pod`] except we disregard the rule about it must -/// allow any bit pattern (i.e. it does not need to be -/// [`Zeroable`][crate::Zeroable]). Still, this is a quite strong guarantee -/// about a type, so *be careful* whem implementing it manually. -/// -/// * The type must be inhabited (eg: no -/// [Infallible](core::convert::Infallible)). -/// * The type must not contain any uninit (or padding) bytes, either in the -/// middle or on the end (eg: no `#[repr(C)] struct Foo(u8, u16)`, which has -/// padding in the middle, and also no `#[repr(C)] struct Foo(u16, u8)`, which -/// has padding on the end). -/// * Structs need to have all fields also be `NoUninit`. -/// * Structs need to be `repr(C)` or `repr(transparent)`. In the case of -/// `repr(C)`, the `packed` and `align` repr modifiers can be used as long as -/// all other rules end up being followed. -/// * Enums need to have an explicit `#[repr(Int)]` -/// * Enums must have only fieldless variants -/// * It is disallowed for types to contain pointer types, `Cell`, `UnsafeCell`, -/// atomics, and any other forms of interior mutability. -/// * More precisely: A shared reference to the type must allow reads, and -/// *only* reads. RustBelt's separation logic is based on the notion that a -/// type is allowed to define a sharing predicate, its own invariant that must -/// hold for shared references, and this predicate is the reasoning that allow -/// it to deal with atomic and cells etc. We require the sharing predicate to -/// be trivial and permit only read-only access. -/// * There's probably more, don't mess it up (I mean it). -pub unsafe trait NoUninit: Sized + Copy + 'static {} - -unsafe impl<T: Pod> NoUninit for T {} - -unsafe impl NoUninit for char {} - -unsafe impl NoUninit for bool {} - -unsafe impl NoUninit for NonZeroU8 {} -unsafe impl NoUninit for NonZeroI8 {} -unsafe impl NoUninit for NonZeroU16 {} -unsafe impl NoUninit for NonZeroI16 {} -unsafe impl NoUninit for NonZeroU32 {} -unsafe impl NoUninit for NonZeroI32 {} -unsafe impl NoUninit for NonZeroU64 {} -unsafe impl NoUninit for NonZeroI64 {} -unsafe impl NoUninit for NonZeroU128 {} -unsafe impl NoUninit for NonZeroI128 {} -unsafe impl NoUninit for NonZeroUsize {} -unsafe impl NoUninit for NonZeroIsize {} |