This commit amends the documentation of `Vec::as_mut_ptr` and
`Vec::into_raw_parts` to make it explicit that such calls may be paired
with calls to `dealloc` with a suitable layout. This guarantee was
effectively already provided by the docs of `Vec::from_raw_parts`
mentioning `alloc`.
Additionally, we copy-paste and adjust the “Memory layout” section from
the documentation of `std::boxed` to `std::vec`. This explains the allocator
guarantees in more detail.
Improve formatting of doc code blocks
We don't currently apply automatic formatting to doc comment code blocks. As a
result, it has built up various idiosyncracies, which make such automatic
formatting difficult. Some of those idiosyncracies also make things harder for
human readers or other tools.
This PR makes a few improvements to doc code formatting, in the hopes of making
future automatic formatting easier, as well as in many cases providing net
readability improvements.
I would suggest reading each commit separately, as each commit contains one
class of changes.
This leads tools like rustfmt to get confused, because the doc code
block effectively spans two doc comments. As a result, the tools think
the first code block is unclosed, and the subsequent terminator opens a
new block.
Move the FIXME comments outside the doc code blocks, instead.
Because doc code does not get automatically formatted, some doc code has
creative placements of comments that automatic formatting can't handle.
Reformat those comments to make the resulting code support standard Rust
formatting without breaking; this is generally an improvement to
readability as well.
Some comments are not indented to the prevailing indent, and are instead
aligned under some bit of code. Indent them to the prevailing indent,
and put spaces *inside* the comments to align them with code.
Some comments span several lines of code (which aren't the line the
comment is about) and expect alignment. Reformat them into one comment
not broken up by unrelated intervening code.
Some comments are placed on the same line as an opening brace, placing
them effectively inside the subsequent block, such that formatting would
typically format them like a line of that block. Move those comments to
attach them to what they apply to.
Some comments are placed on the same line as a one-line braced block,
effectively attaching them to the closing brace, even though they're
about the code inside the block. Reformat to make sure the comment will
stay on the same line as the code it's commenting.
`std::vec`: Add UB check for `set_len`, `from_raw_parts_in`, and etc.
Closesrust-lang/rust#143813
I noticed that `from_parts_in` do the similar things like `from_raw_parts_in`, so I add the UB check in the last commit. If it is not appropriate, I will remove it.
And I fix a typo in the first commit.
r? `@scottmcm`
Rollup of 11 pull requests
Successful merges:
- rust-lang/rust#131923 (Derive `Copy` and `Hash` for `IntErrorKind`)
- rust-lang/rust#138340 (Remove some unsized tuple impls now that we don't support unsizing tuples anymore)
- rust-lang/rust#141219 (Change `{Box,Arc,Rc,Weak}::into_raw` to only work with `A = Global`)
- rust-lang/rust#142212 (bootstrap: validate `rust.codegen-backends` & `target.<triple>.codegen-backends`)
- rust-lang/rust#142237 (Detect more cases of unused_parens around types)
- rust-lang/rust#142964 (Attribute rework: a parser for single attributes without arguments)
- rust-lang/rust#143070 (Rewrite `macro_rules!` parser to not use the MBE engine itself)
- rust-lang/rust#143235 (Assemble const bounds via normal item bounds in old solver too)
- rust-lang/rust#143261 (Feed `explicit_predicates_of` instead of `predicates_of`)
- rust-lang/rust#143276 (loop match: handle opaque patterns)
- rust-lang/rust#143306 (Add `track_caller` attributes to trace origin of Clippy lints)
r? `@ghost`
`@rustbot` modify labels: rollup
try-job: aarch64-apple
try-job: x86_64-msvc-1
try-job: x86_64-gnu
try-job: dist-i586-gnu-i586-i686-musl
try-job: test-various
Also applies to `Vec::into_raw_parts`.
The expectation is that you can round-trip these methods with
`from_raw`, but this is only true when using the global allocator. With
custom allocators you should instead be using
`into_raw_with_allocator` and `from_raw_in`.
The implementation of `Box::leak` is changed to use
`Box::into_raw_with_allocator` and explicitly leak the allocator (which
was already the existing behavior). This is because, for `leak` to be
safe, the allocator must not free its underlying backing store. The
`Allocator` trait only guarantees that allocated memory remains valid
until the allocator is dropped.
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>
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
document capacity for ZST as example
The main text already covers this, although it provides weaker guarantees, but I think an example in the right spot does not hurt. Fixes#80747
Use `std::mem::{size_of, size_of_val, align_of, align_of_val}` from the
prelude instead of importing or qualifying them.
These functions were added to all preludes in Rust 1.80.
