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Add support for arbritrary arrays #55

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merged 2 commits into from
Mar 29, 2021
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c410-f3r
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T: Default would remove all unsafes but it isn't currently possible for [T; N] and this bound limitation isn't desirable for stuff that don't implement Default.

If rust-lang/rust#75644 is going to be accepted, then the auxiliary functions won't be necessary in the near future.

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fitzgen commented Sep 14, 2020

I would prefer not to have nightly-only features in this crate.

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@fitzgen You might have a better insight but I am betting on 1.49 that is going to be released on 2020-12-31

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fitzgen commented Sep 14, 2020

I don't have any insider insight here, but I'd prefer revisiting after it merges to stable. Happy to leave this PR open until then.

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The time has come.

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Looks good to me, modulo a couple nitpicks below. Fix those up and then we can merge this! Thanks @c410-f3r!

src/lib.rs Outdated
{
let mut array: mem::MaybeUninit<[T; N]> = mem::MaybeUninit::uninit();
let mut guard: ArrayGuard<T, N> = ArrayGuard {
dst: array.as_mut_ptr() as _,
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What is the as cast doing here? Converting from *mut [T; N] to *mut T? If so, can we lift that to multiple lets that show the types, like this:

let dst: *mut [T; N] = array.as_mut_ptr();
let dst: *mut T = dst as _;
// ...

fn arbitrary_take_rest(mut u: Unstructured<'a>) -> Result<[T; $n]> {
$(let $as = $ts::arbitrary(&mut u)?;)*
let last = Arbitrary::arbitrary_take_rest(u)?;
struct ArrayGuard<T, const N: usize> {
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Could you add a little documentation for what role this guard plays? That will help future readers of this code.

src/lib.rs Outdated
{
let mut array: mem::MaybeUninit<[T; N]> = mem::MaybeUninit::uninit();
let mut guard: ArrayGuard<T, N> = ArrayGuard {
dst: array.as_mut_ptr() as _,
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Ditto regarding the as here.

@c410-f3r c410-f3r changed the title Add const-generics feature Add support for arbritrary arrays Mar 29, 2021
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Done. Thanks for the review

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fitzgen commented Mar 29, 2021

Thanks!

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