Docs(lib): Fix `extract_if` docs
Various fixes to the documentation comments of the several `extract_if` collection methods available. It originally started with a small typo fix in `Vec`'s spotted when reading the 1.87 release notes, but then by looking at the others' for comparison in order to try determining what was the intended sentence, some inconsistencies were spotted. Therefore, some other changes are also proposed here to reduce these avoidable differences, going more and more nit-picky along the way. See the individual commits for more details about each change.
`@rustbot` label T-libs A-collections A-docs
add doc alias `replace_first` for `str::replacen`
`replace_first` is a sensible name for a function, analogous to actually existing `<[_]>::split_first`, for example. (I just saw someone try to search for it)
I think it's reasonable to add such an alias for `replacen`, which replaces the first occurrence of passed a 1.
use `Self` alias in self types rather than manually substituting it
Of the rougly 145 uses of `self: Ty` in the standard library, 5 of them don't use `Self` but instead choose to manually "substitute" the `impl`'s self type into the type.
This leads to weird behavior sometimes (https://github.com/rust-lang/rust/issues/140611#issuecomment-2883761300) -- **to be clear**, none of these usages actually trigger any bugs, but it's possible that they may break in the future (or at least lead to lints), so let's just "fix" them proactively.
Take the one from `BTreeMap` that seems the best-worded and most
precise among the available variations.
Signed-off-by: Paul Mabileau <paul.mabileau@harfanglab.fr>
This also seems like a small mistake: the first main sentence is put in
the same paragraph as the other two following ones while other
equivalents all have it split. Therefore, do the same here.
Signed-off-by: Paul Mabileau <paul.mabileau@harfanglab.fr>
Comment on `Rc` abort-guard strategy without naming unrelated fn
`wrapped_add` is used, not `checked_add`, so avoid mentioning specific fn calls that may vary slightly based on "whatever produces the best code" and focus on things that will remain constant into the future.
Consistent trait bounds for ExtractIf Debug impls
Closes#137654. Refer to that issue for a table of the **4** different impl signatures we previously had in the standard library for Debug impls of various ExtractIf iterator types.
The one we are standardizing on is the one so far only used by `alloc::collections::linked_list::ExtractIf`, which is _no_ `F: Debug` bound, _no_ `F: FnMut` bound, only `T: Debug` bound.
This PR applies the following signature changes:
```diff
/* alloc::collections::btree_map */
pub struct ExtractIf<'a, K, V, F, A = Global>
where
- F: 'a + FnMut(&K, &mut V) -> bool,
Allocator + Clone,
impl Debug for ExtractIf<'a, K, V, F,
+ A,
>
where
K: Debug,
V: Debug,
- F: FnMut(&K, &mut V) -> bool,
+ A: Allocator + Clone,
```
```diff
/* alloc::collections::btree_set */
pub struct ExtractIf<'a, T, F, A = Global>
where
- T: 'a,
- F: 'a + FnMut(&T) -> bool,
Allocator + Clone,
impl Debug for ExtractIf<'a, T, F, A>
where
T: Debug,
- F: FnMut(&T) -> bool,
A: Allocator + Clone,
```
```diff
/* alloc::collections::linked_list */
impl Debug for ExtractIf<'a, T, F,
+ A,
>
where
T: Debug,
+ A: Allocator,
```
```diff
/* alloc::vec */
impl Debug for ExtractIf<'a, T, F, A>
where
T: Debug,
- F: Debug,
A: Allocator,
- A: Debug,
```
```diff
/* std::collections::hash_map */
pub struct ExtractIf<'a, K, V, F>
where
- F: FnMut(&K, &mut V) -> bool,
impl Debug for ExtractIf<'a, K, V, F>
where
+ K: Debug,
+ V: Debug,
- F: FnMut(&K, &mut V) -> bool,
```
```diff
/* std::collections::hash_set */
pub struct ExtractIf<'a, T, F>
where
- F: FnMut(&T) -> bool,
impl Debug for ExtractIf<'a, T, F>
where
+ T: Debug,
- F: FnMut(&T) -> bool,
```
I have made the following changes to bring these types into better alignment with one another.
- Delete `F: Debug` bounds. These are especially problematic because Rust closures do not come with a Debug impl, rendering the impl useless.
- Delete `A: Debug` bounds. Allocator parameters are unstable for now, but in the future this would become an API commitment that we do not debug-print a representation of the allocator when printing an iterator.
- Delete `F: FnMut` bounds. Requires `hashbrown` PR: https://github.com/rust-lang/hashbrown/pull/616. **API commitment:** we commit to not doing RefCell voodoo inside ExtractIf to have some way for its Debug impl (which takes &self) to call a FnMut closure, if this is even possible.
- Add `T: Debug` bounds (or `K`/`V`), even on Debug impls that do not currently make use of them, but might in the future. **Breaking change.** Must backport into Rust 1.87 (current beta) or do a de-stabilization PR in beta to delay those types by one release.
- Render using `debug_struct` + `finish_non_exhaustive`, instead of `debug_tuple`.
- Do not render the _entire_ underlying collection.
- Show a "peek" field indicating the current position of the iterator.
Correct `extract_if` sample equivalent.
Tracking issue: https://github.com/rust-lang/rust/issues/43244
Original PR: #133265
The sample code marked as equivalent in the doc comment isn't currently equivalent. Given the same predicate and range, if your vector were `[1, 2, 3, 3, 3, 3, 3, 3, 4, 5, 6]`, then all of the 3s would be removed. `i` is only incremented when an element is dropped, but `range.end` is unchanged, so the items shift down. I got very confused when reading the docs and trying to square this sample code with the explanation of how the function works.
Fortunately, the real `extract_if()` does not have this problem. I've added an `end` variable to align the behavior. I've also taken the opportunity to simplify the predicate, which now just matches odd numbers, and to pad out the vec of numbers to line up the zero-indexed range with the integers in the vec.
r? the8472
Implement a lint for implicit autoref of raw pointer dereference - take 2
*[t-lang nomination comment](https://github.com/rust-lang/rust/pull/123239#issuecomment-2727551097)*
This PR aims at implementing a lint for implicit autoref of raw pointer dereference, it is based on #103735 with suggestion and improvements from https://github.com/rust-lang/rust/pull/103735#issuecomment-1370420305.
The goal is to catch cases like this, where the user probably doesn't realise it just created a reference.
```rust
pub struct Test {
data: [u8],
}
pub fn test_len(t: *const Test) -> usize {
unsafe { (*t).data.len() } // this calls <[T]>::len(&self)
}
```
Since #103735 already went 2 times through T-lang, where they T-lang ended-up asking for a more restricted version (which is what this PR does), I would prefer this PR to be reviewed first before re-nominating it for T-lang.
----
Compared to the PR it is as based on, this PR adds 3 restrictions on the outer most expression, which must either be:
1. A deref followed by any non-deref place projection (that intermediate deref will typically be auto-inserted)
2. A method call annotated with `#[rustc_no_implicit_refs]`.
3. A deref followed by a `addr_of!` or `addr_of_mut!`. See bottom of post for details.
There are several points that are not 100% clear to me when implementing the modifications:
- ~~"4. Any number of automatically inserted deref/derefmut calls." I as never able to trigger this. Am I missing something?~~ Fixed
- Are "index" and "field" enough?
----
cc `@JakobDegen` `@WaffleLapkin`
r? `@RalfJung`
try-job: dist-various-1
try-job: dist-various-2
Create `Atomic<T>` type alias (rebase)
Rebase of #130543.
Additional changes:
- Switch from `allow` to `expect` for `private_bounds` on `AtomicPrimitive`
- Unhide `AtomicPrimitive::AtomicInner` from docs, because rustdoc shows the definition `pub type Atomic<T> = <T as AtomicPrimitive>::AtomicInner;` and generated links for it.
- `NonZero` did not have this issue, because they kept the new alias private before the direction was changed.
- Use `Atomic<_>` in more places, including inside `Once`'s `Futex`. This is possible thanks to https://github.com/rust-lang/rust-clippy/pull/14125
The rest will either get moved back to #130543 or #130543 will be closed in favor of this instead.
---
* ACP: https://github.com/rust-lang/libs-team/issues/443#event-14293381061
* Tracking issue: #130539
Update safety documentation for `CString::from_ptr` and `str::from_boxed_utf8_unchecked`
## PR Description
This PR addresses missing safety documentation for two APIs:
**1. alloc::ffi::CStr::from_raw**
- `Alias`: The pointer must not be aliased (accessed via other pointers) during the reconstructed CString's lifetime.
- `Owning`: Calling this function twice on the same pointer and creating two objects with overlapping lifetimes, introduces two alive owners of the same memory. This may result in a double-free.
- `Dangling`: The prior documentation required the pointer to originate from CString::into_raw, but this constraint is incomplete. A validly sourced pointer can also cause undefined behavior (UB) if it becomes dangling. A simple Poc for this situation:
```
use std::ffi::CString;
use std::os::raw::c_char;
fn create_dangling() -> *mut c_char {
let local_ptr: *mut c_char = {
let valid_data = CString::new("valid").unwrap();
valid_data.into_raw()
};
unsafe {
let _x = CString::from_raw(local_ptr);
}
local_ptr
}
fn main() {
let dangling = create_dangling();
unsafe {let _y = CString::from_raw(dangling);} // Cause UB!
}
```
**2. alloc::str::from_boxed_utf8_unchecked**
- `ValidStr`: Bytes must contain a valid UTF-8 sequence.
