Function constmuck::try_cast_slice_alt

pub const fn try_cast_slice_alt<T, U>(
    from: &[T], 
    _bounds: (IsPod<T>, IsPod<U>)
) -> Result<&[U], PodCastError>

Tries to cast &[T] to &[U]

Requires both T and U to implement Pod.

Errors

This function returns errors in these cases:

• The alignment of T is larger than U, returning a Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned).
  (using this instead of PodCastError::AlignmentMismatch because that is not returned by bytemuck::try_cast_slice)

• The size of T is not equal to U, returning a Err(PodCastError::SizeMismatch).

Difference with bytemuck

This function requires T to have an alignment larger or equal to U, while bytemuck::try_cast_slice only requires the from reference to happen to be aligned to U.

bytemuck::try_cast_slice allows the size of T to be different than U if it divides evenly into it, this function does not due to limitations in stable const fns.

Example

use constmuck::PodCastError;
use constmuck::{infer, try_cast_slice_alt};

type Res<T> = Result<T, PodCastError>;

const I8S: Res<&[i8]> = try_cast_slice_alt(&[100u8, 254, 255], infer!());
const ERR_SIZE : Res<&[u8]> = try_cast_slice_alt(&[0u16], infer!());

assert_eq!(I8S, Ok(&[100i8, -2, -1][..]));
assert_eq!(ERR_SIZE, Err(PodCastError::SizeMismatch));