Add try_shrink_to and try_shrink_to_fit to Vec
Adds the functions `try_shrink_to` and `try_shrink_to_fit` to Vec to allow shrinking
in environments without global OOM handling.
The implementation differs from the tracking issue as the fallible methods return
a `TryReserveError` instead of an `AllocError` as `AllocError` is unstable and does
not contain layout information.
Tracking:
- rust-lang/rust#152350
* Add try_shrink_to and try_shrink_to_fit to Vec
Both functions are required to support shrinking a vector in
environments without global OOM handling.
* Format the try_shrink functions
* Remove excess "```" from doc
* Remove `cfg(not(no_global_oom_handling))` from rawvecinner::shrink
* Fix import cmp even if no_global_oom_handling is defined
This reverts PR <https://github.com/rust-lang/rust/pull/130998> because
the added test seems to be flaky / non-deterministic, and has been
failing in unrelated PRs during merge CI.
`Vec::push` in consts MVP
Example:
```rust
const X: &'static [u32] = {
let mut v = Vec::with_capacity(6);
let mut x = 1;
while x < 42 {
v.push(x);
x *= 2;
}
assert!(v.len() == 6);
v.const_make_global()
};
assert_eq!([1, 2, 4, 8, 16, 32], X);
```
Oh this is fun...
* We split out the implementation of `Global` such that it calls `intrinsics::const_allocate` and `intrinsics::const_deallocate` during compile time. This is achieved using `const_eval_select`
* This allows us to `impl const Allocator for Global`
* We then constify everything necessary for `Vec::with_capacity` and `Vec::push`.
* Added `Vec::const_make_global` to leak and intern the final value via `intrinsics::const_make_global`. If we see any pointer in the final value of a `const` that did not call `const_make_global`, we error as implemented in rust-lang/rust#143595.
r? `@rust-lang/wg-const-eval`
To-do for me:
* [x] Assess the rustdoc impact of additional bounds in the method
* [x] ~~Increase test coverage~~ I think this is enough for an unstable feature.
alloc: Document panics when allocations will exceed max
Document panics in `String` and `Vec` due to capacity overflowing `isize::MAX`. Correct outdated claims of `usize::MAX` limit.
Fixes https://github.com/rust-lang/rust/issues/148598.
Ping `@lolbinarycat`
Stabilize vec_into_raw_parts
This stabilizes `Vec::into_raw_parts()` and `String::into_raw_parts()` per FCP in https://github.com/rust-lang/rust/issues/65816#issuecomment-3517630971. While this _does not_ stabilize `Vec::into_parts()`, I fixed up the examples that said they were waiting for `vec_into_raw_parts`. As `Vec::from_parts()` and `Vec::into_parts()` are covered by the same feature `box_vec_non_null`, any doctest that uses `Vec::from_parts()` can also use `Vec::into_parts()` (and same for allocator-aware versions).
Closesrust-lang/rust#65816
``@rustbot`` modify labels: +T-libs-api
Remove most `#[track_caller]` from allocating Vec methods
They cause significant binary size overhead while contributing little value.
closesrust-lang/rust#146963, see that issue for more details.
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`
Josh Stone