Closes rust-lang#60783

…raviscross

Reserve guarded string literals (RFC 3593)

Implementation for RFC 3593, including:
- lexer / parser changes
- diagnostics
- migration lint
- tests

We reserve `#"`, `##"`, `###"`, `####`, and any other string of four or more repeated `#`. This avoids infinite lookahead in the lexer, though we still use infinite lookahead in the parser to provide better forward compatibility diagnostics.

This PR does not implement any special lexing of the string internals:
- strings preceded by one or more `#` are denied
- regardless of the number of trailing `#`
- string contents are lexed as if it was just a bare `"string"`

Tracking issue: rust-lang#123735
RFC: rust-lang/rfcs#3593

…pat, r=ibraheemdev

Library: Rename "object safe" to "dyn compatible"

Completed T-lang FCP: rust-lang/lang-team#286 (comment).
Tracking issue: rust-lang#130852

Regarding https://github.com/rust-lang/rust/labels/relnotes, I guess I will manually open a https://github.com/rust-lang/rust/labels/relnotes-tracking-issue since this change affects everything (compiler, library, tools, docs, books, everyday language).

r? ghost

…_slice_slicing_at_ends, r=cuviper

Add docs about slicing slices at the ends

Closes rust-lang#60783

…_p2, r=petrochenkov

Fix needless_lifetimes in rustc_serialize

Hi,

This PR fixes the following clipy warnings:

```
warning: the following explicit lifetimes could be elided: 'a
   --> compiler/rustc_serialize/src/serialize.rs:328:6
    |
328 | impl<'a, S: Encoder, T: Encodable<S>> Encodable<S> for Cow<'a, [T]>
    |      ^^                                                    ^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
    = note: `#[warn(clippy::needless_lifetimes)]` on by default
help: elide the lifetimes
    |
328 - impl<'a, S: Encoder, T: Encodable<S>> Encodable<S> for Cow<'a, [T]>
328 + impl<S: Encoder, T: Encodable<S>> Encodable<S> for Cow<'_, [T]>
    |

warning: the following explicit lifetimes could be elided: 'a
   --> compiler/rustc_serialize/src/serialize.rs:348:6
    |
348 | impl<'a, S: Encoder> Encodable<S> for Cow<'a, str> {
    |      ^^                                   ^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
help: elide the lifetimes
    |
348 - impl<'a, S: Encoder> Encodable<S> for Cow<'a, str> {
348 + impl<S: Encoder> Encodable<S> for Cow<'_, str> {
    |

warning: the following explicit lifetimes could be elided: 'a
   --> compiler/rustc_serialize/src/serialize.rs:355:6
    |
355 | impl<'a, D: Decoder> Decodable<D> for Cow<'a, str> {
    |      ^^                                   ^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
help: elide the lifetimes
    |
355 - impl<'a, D: Decoder> Decodable<D> for Cow<'a, str> {
355 + impl<D: Decoder> Decodable<D> for Cow<'_, str> {
```

Best regards,
Michal

…-margin, r=notriddle

Fix methods alignment on mobile

I realized that on mobile, the methods are not aligned the same depending if they have documentation or not:

| before | after |
|-|-|
| ![Screenshot from 2024-10-08 20-40-22](https://github.com/user-attachments/assets/d31ba5e1-cf84-431f-9b2b-9962bc5a0365) | ![image](https://github.com/user-attachments/assets/ffde2161-bfcb-4462-8c5b-88538e61b366) |

r? `@notriddle`

…alexcrichton

Decouple WASIp2 sockets from WasiFd

This is a follow up to rust-lang#129638, decoupling WASIp2's socket implementation from WASIp1's `WasiFd` as discussed with `@alexcrichton.`

Quite a few trait implementations in `std::os::fd` rely on the fact that there is an additional layer of abstraction between `Socket` and `OwnedFd`. I thus had to add a thin `WasiSocket` wrapper struct that just "forwards" to `OwnedFd`. Alternatively, I could have added a lot of conditional compilation to `std::os::fd`, which feels even worse.

Since `WasiFd::sock_accept` is no longer accessible from `TcpListener` and since WASIp2 has proper support for accepting sockets through `Socket::accept`, the `std::os::wasi::net` module has been removed from WASIp2, which only contains a single `TcpListenerExt` trait with a `sock_accept` method as well as an implementation for `TcpListener`. Let me know if this is an acceptable solution.

…fJung

Mention allocation errors for `open_buffered`

This documents that `File::open_buffered` may return an error on allocation failure.