Refactor core::iter module
A while back, I refactored `core::ops` in #42523 because the module had become a giant mess and was difficult to modify. Now, I'm doing the same with the `core::iter` module.
Like the `core::ops` refactor, things have been split up into multiple commits to make rebasing easier, and so that you can follow changes. Although the diffs are hard to decipher, the only actual code changes I've made in the first few commits are to modify exports and imports. I save all of the actual code refactoring, e.g. modifying what methods are called, for the end.
Add core::iter::once_with()
Functions `iter::once()` and `iter::repeat()` construct iterators from values. The latter has the lazy variant `iter::repeat_with()`, but the former doesn't. This PR therefore adds `iter::once_with()`.
Another way to think of `iter::once_with()` is that it's a function that converts `FnOnce() -> T` into `Iterator<Item = T>`.
If this seems like a reasonable addition, I'll open a tracking issue and update the `#[feature(...)]` attributes.
Update the stdsimd submodule
This brings in a few updates:
* Update wasm intrinsic naming for atomics
* Update and reimplement most simd128 wasm intrinsics
* Other misc improvements here and there, including a small start to
AVX-512 intrinsics
deny intra-doc link resolution failures in libstd
Fixes#56693.
Until we land a fix for the underlying issue (#56922), we can at least fix the failures in libstd so they don't propagate to downstream crates.
Fix various aspects around `let` bindings inside const functions
* forbid `let` bindings in const contexts that use short circuiting operators
* harden analysis code against derefs of mutable references
Initially this PR was about stabilizing `let` bindings, but too many flaws were exposed that need some more testing on nightly
This brings in a few updates:
* Update wasm intrinsic naming for atomics
* Update and reimplement most simd128 wasm intrinsics
* Other misc improvements here and there, including a small start to
AVX-512 intrinsics
Hopefully just another routine update!
So far this starts to enable the `std::arch` in stage0 builds of rustc.
This means that we may need stage0/not(stage0) in stdsimd itself, but
more and more code is starting to use `std::arch` so I think it's time
to start shifting the balance of work here.
Add mem::forget_unsized() for forgetting unsized values
~~Allows passing values of `T: ?Sized` types to `mem::drop` and `mem::forget`.~~
Adds `mem::forget_unsized()` that accepts `T: ?Sized`.
I had to revert the PR that removed the `forget` intrinsic and replaced it with `ManuallyDrop`: https://github.com/rust-lang/rust/pull/40559
We can't use `ManuallyDrop::new()` here because it needs `T: Sized` and we don't have support for unsized return values yet (will we ever?).
r? @eddyb
Make PhantomData #[structural_match]
fixes https://github.com/rust-lang/rust/issues/55028
This makes `PhantomData<T>` structurally matchable, irrespective of whether `T` is, per the discussion on this week's language team meeting (the general consensus was that this was a bug-fix).
All types containing `PhantomData<T>` and which used `#[derive(PartialEq, Eq)]` and were previously not `#[structural_match]` only because of `PhantomData<T>` will now be `#[structural_match]`.
r? @nikomatsakis
