rustix/
types.rs

1//! Platform-agnostic support types.
2//!
3//! Copied from https://github.com/rust-lang/libc/blob/008f905256d27eb5dd416d0976678ee6c2855554/src/types.rs
4
5use core::fmt;
6use core::mem::MaybeUninit;
7
8/// A transparent wrapper over `MaybeUninit<T>` to represent uninitialized padding
9/// while providing `Default`.
10// This is restricted to `Copy` types since that's a loose indicator that zeros is actually
11// a valid bitpattern. There is no technical reason this is required, though, so it could be
12// lifted in the future if it becomes a problem.
13#[allow(dead_code)]
14#[repr(transparent)]
15#[derive(Clone, Copy)]
16pub(crate) struct Padding<T: Copy>(MaybeUninit<T>);
17
18impl<T: Copy> Default for Padding<T> {
19    fn default() -> Self {
20        Self(MaybeUninit::zeroed())
21    }
22}
23
24impl<T: Copy> Padding<T> {
25    /// Create a `Padding` initialized with the given value.
26    #[allow(dead_code)]
27    pub(crate) const fn new(val: T) -> Self {
28        Self(MaybeUninit::new(val))
29    }
30}
31
32impl<T: Copy> fmt::Debug for Padding<T> {
33    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
34        // Taken from `MaybeUninit`'s debug implementation
35        // NB: there is no `.pad_fmt` so we can't use a simpler `format_args!("Padding<{..}>").
36        let full_name = core::any::type_name::<Self>();
37        let prefix_len = full_name.find("Padding").unwrap();
38        f.pad(&full_name[prefix_len..])
39    }
40}
rustix/types.rs

rustix/
types.rs
