Documentation: Fix Stilted Language in Vec->Indexing
Problem
Language in the Vec->Indexing documentation sounds stilted due to incorrect word ordering: "... type allows to access values by index."
Solution
Reorder words in the Vec->Indexing documentation to flow better: "... type allows access to values by index." The phrase "allows access to" also matches other existing documentation.
Clarify behavior of inclusive bounds in BTreeMap::{lower,upper}_bound
It wasn’t quite clear to me how these methods would interpret inclusive bounds so I added examples for those.
Remove redundant example of `BTreeSet::iter`
The usage and that `Values returned by the iterator are returned in ascending order` are already demonstrated by the other example and the description, so I removed the useless one.
Problem
Language in the Vec->Indexing documentation sounds stilted due to
incorrect word ordering: "... type allows to access values by index."
Solution
Reorder words in the Vec->Indexing documentation to flow better:
"... type allows access to values by index." The phrase "allows access to"
also matches other existing documentation.
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.
Multibyte character removal in String::pop and String::remove doctests
I think it would be useful to have the doctests for the `String::pop()` and `String::remove()` methods demonstrate that they work on multibyte UTF-8 sequences.
Fix size_hint for EncodeUtf16
More realistic upper and lower bounds, and handle the case where the iterator is located within a surrogate pair.
Resolves#113897
Add support for allocators in `Rc` & `Arc`
Adds the ability for `std::rc:Rc`, `std::rc::Weak`, `std::sync::Arc`, and `std::sync::Weak` to live in custom allocators
Rename VecDeque's `rotate_left` and `rotate_right` parameters
This pull request introduces a modification to the `VecDeque` collection, specifically the `rotate_left` and `rotate_right` functions, by renaming the parameter associated with these functions.
The rationale behind this change is to provide clearer and more consistent naming for the parameter that specifies the number of places to rotate the double-ended queue. By using `n` as the parameter name in both functions, it becomes easier to understand and remember the purpose of the parameter.
Eliminate ZST allocations in `Box` and `Vec`
This PR fixes 2 issues with `Box` and `RawVec` related to ZST allocations. Specifically, the `Allocator` trait requires that:
- If you allocate a zero-sized layout then you must later deallocate it, otherwise the allocator may leak memory.
- You cannot pass a ZST pointer to the allocator that you haven't previously allocated.
These restrictions exist because an allocator implementation is allowed to allocate non-zero amounts of memory for a zero-sized allocation. For example, `malloc` in libc does this.
Currently, ZSTs are handled differently in `Box` and `Vec`:
- `Vec` never allocates when `T` is a ZST or if the vector capacity is 0.
- `Box` just blindly passes everything on to the allocator, including ZSTs.
This causes problems due to the free conversions between `Box<[T]>` and `Vec<T>`, specifically that ZST allocations could get leaked or a dangling pointer could be passed to `deallocate`.
This PR fixes this by changing `Box` to not allocate for zero-sized values and slices. It also fixes a bug in `RawVec::shrink` where shrinking to a size of zero did not actually free the backing memory.
Revert "alloc: Allow comparing Boxs over different allocators", add regression test
Temporary fix for #113283
Adds a test to fix the regression introduced in 001b081cc1 and revert that commit. The test fails without the revert.
This reverts commit 001b081cc1.
This change was done as the above commit introduces a regression in type
inference. Regression test located at
`tests/ui/type-inference/issue-113283-alllocator-trait-eq.rs`
Allow comparing `Box`es with different allocators
Currently, comparing `Box`es over different allocators is not allowed:
```Rust
error[E0308]: mismatched types
--> library/alloc/tests/boxed.rs:22:20
|
22 | assert_eq!(b1, b2);
| ^^ expected `Box<{integer}, ConstAllocator>`, found `Box<{integer}, AnotherAllocator>`
|
= note: expected struct `Box<{integer}, ConstAllocator>`
found struct `Box<{integer}, AnotherAllocator>`
For more information about this error, try `rustc --explain E0308`.
error: could not compile `alloc` (test "collectionstests") due to previous error
```
This PR lifts this limitation
remove unused field
Followup to #104455. The field is no longer needed since ExtractIf (previously DrainFilter) doesn't keep draining in its drop impl.
Implement PartialOrd for `Vec`s over different allocators
It is already possible to `PartialEq` `Vec`s with different allocators, but that is not the case with `PartialOrd`.
This is an `Rc` that is guaranteed to only have one strong reference.
Because it is uniquely owned, it can safely implement `DerefMut`, which
allows programs to have an initialization phase where structures inside
the `Rc` can be mutated.
The `UniqueRc` can then be converted to a regular `Rc`, allowing sharing
and but read-only access.
During the "initialization phase," weak references can be created, but
attempting to upgrade these will fail until the `UniqueRc` has been
converted to a regular `Rc`. This feature can be useful to create
cyclic data structures.
This API is an implementation based on the feedback provided to the ACP
at https://github.com/rust-lang/libs-team/issues/90.
Remove `box_free` lang item
This PR removes the `box_free` lang item, replacing it with `Box`'s `Drop` impl. Box dropping is still slightly magic because the contained value is still dropped by the compiler.
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.
Ignore `core`, `alloc` and `test` tests that require unwinding on `-C panic=abort`
Some of the tests for `core` and `alloc` require unwinding through their use of `catch_unwind`. These tests fail when testing using `-C panic=abort` (in my case through a target without unwinding support, and `-Z panic-abort-tests`), while they should be ignored as they don't indicate a failure.
This PR marks all of these tests with this attribute:
```rust
#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
```
I'm not aware of a way to test this on rust-lang/rust's CI, as we don't test any target with `-C panic=abort`, but I tested this locally on a Ferrocene target and it does indeed make the test suite pass.
Uplift `clippy::invalid_utf8_in_unchecked` lint
This PR aims at uplifting the `clippy::invalid_utf8_in_unchecked` lint into two lints.
## `invalid_from_utf8_unchecked`
(deny-by-default)
The `invalid_from_utf8_unchecked` lint checks for calls to `std::str::from_utf8_unchecked` and `std::str::from_utf8_unchecked_mut` with an invalid UTF-8 literal.
### Example
```rust
unsafe {
std::str::from_utf8_unchecked(b"cl\x82ippy");
}
```
### Explanation
Creating such a `str` would result in undefined behavior as per documentation for `std::str::from_utf8_unchecked` and `std::str::from_utf8_unchecked_mut`.
## `invalid_from_utf8`
(warn-by-default)
The `invalid_from_utf8` lint checks for calls to `std::str::from_utf8` and `std::str::from_utf8_mut` with an invalid UTF-8 literal.
### Example
```rust
std::str::from_utf8(b"ru\x82st");
```
### Explanation
Trying to create such a `str` would always return an error as per documentation for `std::str::from_utf8` and `std::str::from_utf8_mut`.
-----
Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
````@rustbot```` label: +I-lang-nominated
r? compiler
-----
For Clippy:
changelog: Moves: Uplifted `clippy::invalid_utf8_in_unchecked` into rustc
Support #[global_allocator] without the allocator shim
This makes it possible to use liballoc/libstd in combination with `--emit obj` if you use `#[global_allocator]`. This is what rust-for-linux uses right now and systemd may use in the future. Currently they have to depend on the exact implementation of the allocator shim to create one themself as `--emit obj` doesn't create an allocator shim.
Note that currently the allocator shim also defines the oom error handler, which is normally required too. Once `#![feature(default_alloc_error_handler)]` becomes the only option, this can be avoided. In addition when using only fallible allocator methods and either `--cfg no_global_oom_handling` for liballoc (like rust-for-linux) or `--gc-sections` no references to the oom error handler will exist.
To avoid this feature being insta-stable, you will have to define `__rust_no_alloc_shim_is_unstable` to avoid linker errors.
(Labeling this with both T-compiler and T-lang as it originally involved both an implementation detail and had an insta-stable user facing change. As noted above, the `__rust_no_alloc_shim_is_unstable` symbol requirement should prevent unintended dependence on this unstable feature.)
Mark internal functions and traits unsafe to reflect preconditions
No semantics are changed in this PR; I only mark some functions and and a trait `unsafe` which already had implicit preconditions. Although it seems somewhat redundant for `numfmt::Part::Copy` to contain a `&[u8]` instead of a `&str`, given that all of its current consumers ultimately expect valid UTF-8. Is the type also intended to work for byte-slice formatting in the future?
Fix duplicate `arcinner_layout_for_value_layout` calls when using the uninit `Arc` constructors
What this fixes is the duplicate calls to `arcinner_layout_for_value_layout` seen here: https://godbolt.org/z/jr5Gxozhj
The issue was discovered alongside #111603 but is otherwise unrelated to the duplicate `alloca`s, which remain unsolved. Everything I tried to solve said main issue has failed.
As for the duplicate layout calculations, I also tried slapping `#[inline]` and `#[inline(always)]` on everything in sight but the only thing that worked in the end is to dedup the calls by hand.
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.
Change Vec examples to not assert exact capacity except where it is guaranteed
It was [brought up on discord](https://discord.com/channels/273534239310479360/818964227783262209/1107633959329878077) that the `Vec::into_boxed_slice` example contradicted the `Vec::with_capacity` docs in that the returned `Vec` might have _more_ capacity than requested.
So, to reduce confusion change all the `assert_eq!(vec.capacity(), _)` to `assert!(vec.capacity() >= _)`, except in 4 examples that have guaranteed capacities: `Vec::from_raw_parts`, `Vec::from_raw_parts_in`, `Vec::<()>::with_capacity`,`Vec::<(), _>::with_capacity_in`.
You will need to add the following as replacement for the old __rust_*
definitions when not using the alloc shim.
#[no_mangle]
static __rust_no_alloc_shim_is_unstable: u8 = 0;
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>
