Rustdoc remove old style files
Reopening of #56577 (which I can't seem to reopen...).
I made the flag unstable so with this change, what was blocking the PR is now gone I assume.
split MaybeUninit into several features, expand docs a bit
This splits the `maybe_uninit` feature gate into several:
* `maybe_uninit` for what we will hopefully stabilize soon-ish.
* `maybe_uninit_ref` for creating references into `MaybeUninit`, for which the rules are not yet clear.
* `maybe_uninit_slice` for handling slices of `MaybeUninit`, which needs more API design work.
* `maybe_uninit_array` for creating arrays of `MaybeUninit` using a macro (because we don't have https://github.com/rust-lang/rust/issues/49147 yet).
Is that an okay thing to do? The goal is to help people avoid APIs we do not want to stabilize yet. I used this to make sure rustc itself does not use `get_ref` and `get_mut`.
I also extended the docs to advise against uninitialized integers -- again this is something for which the rules are still being discussed.
rustdoc: mask `compiler_builtins` docs
Fixes#46783.
I wasn't able to fully confirm the underlying cause, but my theory is that functions in `compiler_builtins` were overwriting functions with the same names in libcore in the search index. Since the functions in `compiler_builtins` didn't have docs, that's why they weren't appearing in the results.
Masking the `compiler_builtins` crate fixes the search results. It appears that this crate was accidentally unmasked in #49503.
Use posix_spawn_file_actions_addchdir_np when possible
This is a non-POSIX extension implemented in Solaris and in glibc 2.29.
With this we can still use `posix_spawn()` when `Command::current_dir()`
has been set, otherwise we fallback to `fork(); chdir(); exec()`.
fix Box::into_unique effecitvely transmuting to a raw ptr
Miri/Stacked Borrows treat `Box` specially: they assert that it is unique, and tag it appropriately. However, currently, `Box::into_inner` is not aware of that and returns a raw pointer (wrapped in a `Unique`) that carries the same tag as the box, meaning it carries a `Uniq` tag. This leads to all sorts of problems when people use the raw pointer they get out of the `Unique` type.
In the future, it'd be interesting to make `Unique` also carry some kind of uniqueness. In that case, something like this would instead be needed whenever a raw pointer is extracted from a `Unique`. However, that is out-of-scope for the current version of Stacked Borrows. So until then, this changes `into_unique` to perform a proper reference-to-raw-ptr-cast, which clears the tag.
Add specific feature gate error for const-unstable features
Before:
```
error: `impl Trait` in const fn is unstable
--> src/lib.rs:7:19
|
7 | const fn foo() -> impl T {
| ^^^^^^
error: aborting due to previous error
```
After:
```
error[E0723]: `impl Trait` in const fn is unstable (see issue #57563)
--> src/lib.rs:7:19
|
7 | const fn foo() -> impl T {
| ^^^^^^
= help: add #![feature(const_fn)] to the crate attributes to enable
error: aborting due to previous error
```
This improves the situation with https://github.com/rust-lang/rust/issues/57563. Fixes https://github.com/rust-lang/rust/issues/57544. Fixes https://github.com/rust-lang/rust/issues/54469.
r? @oli-obk
Stabilize slice_sort_by_cached_key
I was going to ask on the tracking issue (https://github.com/rust-lang/rust/issues/34447), but decided to just send this and hope for an FCP here. The method was added last March by https://github.com/rust-lang/rust/pull/48639.
Signature: https://doc.rust-lang.org/std/primitive.slice.html#method.sort_by_cached_key
```rust
impl [T] {
pub fn sort_by_cached_key<K, F>(&mut self, f: F)
where F: FnMut(&T) -> K, K: Ord;
}
```
That's an identical signature to the existing `sort_by_key`, so I think the questions are just naming, implementation, and the usual "do we want this?".
The implementation seems to have proven its use in rustc at least, which many uses: https://github.com/rust-lang/rust/search?l=Rust&q=sort_by_cached_key
(I'm asking because it's exactly what I just needed the other day:
```rust
all_positions.sort_by_cached_key(|&n|
data::CITIES.iter()
.map(|x| *metric_closure.get_edge(n, x.pos).unwrap())
.sum::<usize>()
);
```
since caching that key is a pretty obviously good idea.)
Closes#34447
