Additional NonZero conversions

[clarfonthey]

ACP: rust-lang/libs-team#145

Requires FCP due to insta-stable APIs added:

impl<T> From<&NonZero<T>> for &T;
impl<T> From<&[NonZero<T>]> for &[T];
impl<T, const N: usize> From<[NonZero<T>; N]> for [T; N];
impl<T> TryFrom<&T> for &NonZero<T>;
impl<T> TryFrom<&[T]> for &[NonZero<T>];
impl<T, const N: usize> TryFrom<[T; N]> for [NonZero<T>; N];

Note that the Error for the TryFrom implementations is TryFromIntError to match the similar impls.

r? rust-lang/libs-api

---

Leaving as a draft at the moment because I'm not sure how to fix the below error:

error[E0119]: conflicting implementations of trait `TryFrom<&_>` for type `&NonZero<_>`
   --> core/src/convert/mod.rs:805:1
    |
805 | / impl<T, U> TryFrom<U> for T
806 | | where
807 | |     U: Into<T>,
    | |_______________^ conflicting implementation for `&NonZero<_>`
    |
   ::: core/src/num/nonzero.rs:310:1
    |
310 | / impl<'a, T> TryFrom<&'a T> for &'a NonZero<T>
311 | | where
312 | |     T: ZeroablePrimitive,
    | |_________________________- first implementation here
    |
    = note: downstream crates may implement trait `convert::From<&_>` for type `&num::nonzero::NonZero<_>`

This shouldn't be possible given the fact that the ZeroablePrimitive trait is sealed, but I'm not quite sure how to fix it. If I can't figure it out before FCP ends, then I'll just replace it with a macro version that enumerates through the options for T.

[bors]

☔ The latest upstream changes (presumably #129750) made this pull request unmergeable. Please resolve the merge conflicts.

[rust-log-analyzer]

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#16 2.839 Building wheels for collected packages: reuse
#16 2.840   Building wheel for reuse (pyproject.toml): started
#16 3.082   Building wheel for reuse (pyproject.toml): finished with status 'done'
#16 3.084   Created wheel for reuse: filename=reuse-4.0.3-cp310-cp310-manylinux_2_35_x86_64.whl size=132715 sha256=dfa09868353292d98f811d3efdb0d54d07389e808efc71d68e3b93c514bf8bec
#16 3.084   Stored in directory: /tmp/pip-ephem-wheel-cache-pfpcc6uy/wheels/3d/8d/0a/e0fc6aba4494b28a967ab5eaf951c121d9c677958714e34532
#16 3.087 Installing collected packages: boolean-py, binaryornot, tomlkit, reuse, python-debian, markupsafe, license-expression, jinja2, chardet, attrs
#16 3.492 Successfully installed attrs-23.2.0 binaryornot-0.4.4 boolean-py-4.0 chardet-5.2.0 jinja2-3.1.4 license-expression-30.3.0 markupsafe-2.1.5 python-debian-0.1.49 reuse-4.0.3 tomlkit-0.13.0
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#16 DONE 3.6s
---
   Compiling std v0.0.0 (/checkout/library/std)
error: unused import: `hint`
  --> core/src/num/nonzero.rs:10:18
   |
10 | use crate::{fmt, hint, intrinsics, ptr, slice, ub_checks};
   |
   = note: `-D unused-imports` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(unused_imports)]`


error[E0119]: conflicting implementations of trait `TryFrom<&_>` for type `&NonZero<_>`
   --> core/src/convert/mod.rs:805:1
    |
805 | / impl<T, U> TryFrom<U> for T
807 | |     U: Into<T>,
807 | |     U: Into<T>,
    | |_______________^ conflicting implementation for `&NonZero<_>`
   ::: core/src/num/nonzero.rs:310:1
    |
    |
310 | / impl<'a, T> TryFrom<&'a T> for &'a NonZero<T>
311 | | where
312 | |     T: ZeroablePrimitive,
    | |_________________________- first implementation here
    |
    = note: downstream crates may implement trait `convert::From<&_>` for type `&num::nonzero::NonZero<_>`
For more information about this error, try `rustc --explain E0119`.
error: could not compile `core` (lib) due to 2 previous errors
Build completed unsuccessfully in 0:00:24
  local time: Sun Sep  1 20:02:44 UTC 2024

[Dylan-DPC]

@clarfonthey since this is waiting on a review, do you still want this to be as a draft? or is this ready for review?

[clarfonthey]

It is ready for review; see the OP.

I should just unmark it as draft and do what I said I was going to do, which is manually implement everything for all the NonZero types. I don't think it's going to be possible to fix the errors unless we actually come up with a way to track sealed traits for coherence, which I don't think is going to happen for a long time.

I'll unmark as draft once I make those changes.