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Remove AsRef/AsMut for [T; N] due to effects to all (even indirect) dependents #132

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Remove AsRef/AsMut for [T; N] due to effects to all (even indirect) dependents #132

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8daf7d7
Remove AsRef for [T; N]
kayabaNerve Aug 29, 2025
8caa508
Remove AsMut for [T; N]
kayabaNerve Aug 29, 2025
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47 changes: 12 additions & 35 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -157,27 +157,6 @@ pub type ArrayN<T, const N: usize> = Array<T, <[T; N] as AssocArraySize>::Size>;
/// let arr: Array<u8, U3> = Array([1, 2, 3]);
/// ```
///
/// ## [`AsRef`] impls
///
/// The [`AsRef`] trait can be used to convert from `&Array<T, U>` to `&[T; N]` and vice versa:
///
/// ```
/// use hybrid_array::{Array, ArraySize, AssocArraySize, ArrayN, sizes::U3};
///
/// pub fn get_third_item_hybrid_array<T, U: ArraySize>(arr_ref: &Array<T, U>) -> &T {
/// &arr_ref[2]
/// }
///
/// pub fn get_third_item_const_generic<T, const N: usize>(arr_ref: &[T; N]) -> &T
/// where
/// [T; N]: AssocArraySize + AsRef<ArrayN<T, N>>
/// {
/// get_third_item_hybrid_array(arr_ref.as_ref())
/// }
Comment on lines -171 to -176
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This is the really sad thing to lose, BTW. It made it possible to write APIs using const generics that hid the use of Array behind the scenes, so the callers didn't have to care about Array at all

///
/// assert_eq!(get_third_item_const_generic(&[1u8, 2, 3, 4]), &3);
/// ```
///
/// Note that the [`AssocArraySize`] trait can be used to determine the appropriate
/// [`Array`] size for a given `[T; N]`, and the [`ArrayN`] trait (which internally uses
/// [`AssocArraySize`]) can be used to determine the specific [`Array`] type for a given
Expand Down Expand Up @@ -486,15 +465,13 @@ where
}
}

impl<T, U, const N: usize> AsRef<Array<T, U>> for [T; N]
#[inline]
fn array_ref_as_hybrid_array_ref<T, U, const N: usize>(array_ref: &[T; N]) -> &Array<T, U>
where
U: ArraySize<ArrayType<T> = [T; N]>,
{
#[inline]
fn as_ref(&self) -> &Array<T, U> {
// SAFETY: `Self` is a `repr(transparent)` newtype for `[T; $len]`
unsafe { &*self.as_ptr().cast() }
}
// SAFETY: `Self` is a `repr(transparent)` newtype for `[T; $len]`
unsafe { &*array_ref.as_ptr().cast() }
}

impl<T, U> AsMut<[T]> for Array<T, U>
Expand All @@ -517,15 +494,15 @@ where
}
}

impl<T, U, const N: usize> AsMut<Array<T, U>> for [T; N]
#[inline]
fn array_mut_ref_as_hybrid_array_mut_ref<T, U, const N: usize>(
array_ref: &mut [T; N],
) -> &mut Array<T, U>
where
U: ArraySize<ArrayType<T> = [T; N]>,
{
#[inline]
fn as_mut(&mut self) -> &mut Array<T, U> {
// SAFETY: `Self` is a `repr(transparent)` newtype for `[T; $len]`
unsafe { &mut *self.as_mut_ptr().cast() }
}
// SAFETY: `Self` is a `repr(transparent)` newtype for `[T; $len]`
unsafe { &mut *array_ref.as_mut_ptr().cast() }
}

impl<T, U> Borrow<[T]> for Array<T, U>
Expand Down Expand Up @@ -663,7 +640,7 @@ where
{
#[inline]
fn from(array_ref: &'a [T; N]) -> &'a Array<T, U> {
array_ref.as_ref()
array_ref_as_hybrid_array_ref(array_ref)
}
}

Expand All @@ -683,7 +660,7 @@ where
{
#[inline]
fn from(array_ref: &'a mut [T; N]) -> &'a mut Array<T, U> {
array_ref.as_mut()
array_mut_ref_as_hybrid_array_mut_ref(array_ref)
}
}

Expand Down