Have `String` use `SliceIndex` impls from `str`
This PR simplifies the implementation of `Index` and `IndexMut` on `String`, and in the process enables indexing `String` by any user types that implement `SliceIndex<str>`.
Similar to #47832
r? libs
Not sure if this warrants a crater run.
Help with common API confusion, like asking for `push` when the data structure really has `append`.
```
error[E0599]: no method named `size` found for struct `Vec<{integer}>` in the current scope
--> $DIR/rustc_confusables_std_cases.rs:17:7
|
LL | x.size();
| ^^^^
|
help: you might have meant to use `len`
|
LL | x.len();
| ~~~
help: there is a method with a similar name
|
LL | x.resize();
| ~~~~~~
```
#59450
Add explicit-endian String::from_utf16 variants
This adds the following APIs under `feature(str_from_utf16_endian)`:
```rust
impl String {
pub fn from_utf16le(v: &[u8]) -> Result<String, FromUtf16Error>;
pub fn from_utf16le_lossy(v: &[u8]) -> String;
pub fn from_utf16be(v: &[u8]) -> Result<String, FromUtf16Error>;
pub fn from_utf16be_lossy(v: &[u8]) -> String;
}
```
These are versions of `String::from_utf16` that explicitly take [UTF-16LE and UTF-16BE](https://unicode.org/faq/utf_bom.html#gen7). Notably, we can do better than just the obvious `decode_utf16(v.array_chunks::<2>().copied().map(u16::from_le_bytes)).collect()` in that:
- We handle the case where the byte slice is not an even number of bytes, and
- In the case that the UTF-16 is native endian and the slice is aligned, we can forward to `String::from_utf16`.
If the Unicode Consortium actively defines how to handle character replacement when decoding a UTF-16 bytestream with a trailing odd byte, I was unable to find reference. However, the behavior implemented here is fairly self-evidently correct: replace the single errant byte with the replacement character.
The status quo is highly confusing, since the overlap is not apparent,
and specialization is not a feature of Rust. This addresses #87545;
I'm not certain if it closes it, since that issue might also be trackign
a *general* solution for hiding specializing impls automatically.
Stabilize String::leak
Stabilizes the following API:
```Rust
impl String {
pub fn leak(self) -> &'static mut str;
}
```
closes#102929
blocked by having an FCP for stabilization.
Specialize ToString implementation for fmt::Arguments
Generates far fewer instructions by formatting into a String with `fmt::format` directly instead of going through the `fmt::Display` impl. This change is insta-stable.
enable `rust_2018_idioms` lint group for doctests
With this change, `rust_2018_idioms` lint group will be enabled for compiler/libstd doctests.
Resolves#106086Resolves#99144
Signed-off-by: ozkanonur <work@onurozkan.dev>
Use associated items of `char` instead of freestanding items in `core::char`
The associated functions and constants on `char` have been stable since 1.52 and the freestanding items have soft-deprecated since 1.62 (https://github.com/rust-lang/rust/pull/95566). This PR ~~marks them as "deprecated in future", similar to the integer and floating point modules (`core::{i32, f32}` etc)~~ replaces all uses of `core::char::*` with `char::*` to prepare for future deprecation of `core::char::*`.
Move Error trait into core
This PR moves the error trait from the standard library into a new unstable `error` module within the core library. The goal of this PR is to help unify error reporting across the std and no_std ecosystems, as well as open the door to integrating the error trait into the panic reporting system when reporting panics whose source is an errors (such as via `expect`).
This PR is a rewrite of https://github.com/rust-lang/rust/pull/90328 using new compiler features that have been added to support error in core.
Guarantee `try_reserve` preserves the contents on error
Update doc comments to make the guarantee explicit. However, some
implementations does not have the statement though.
* `HashMap`, `HashSet`: require guarantees on hashbrown side.
* `PathBuf`: simply redirecting to `OsString`.
Fixes#99606.
Expose `Utf8Lossy` as `Utf8Chunks`
This PR changes the feature for `Utf8Lossy` from `str_internals` to `utf8_lossy` and improves the API. This is done to eventually expose the API as stable.
Proposal: rust-lang/libs-team#54
Tracking Issue: #99543
