Partially stabilize `maybe_uninit_extra`
This covers:
```rust
impl<T> MaybeUninit<T> {
pub unsafe fn assume_init_read(&self) -> T { ... }
pub unsafe fn assume_init_drop(&mut self) { ... }
}
```
It does not cover the const-ness of `write` under `const_maybe_uninit_write` nor the const-ness of `assume_init_read` (this commit adds `const_maybe_uninit_assume_init_read` for that).
FCP: https://github.com/rust-lang/rust/issues/63567#issuecomment-958590287.
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This covers:
impl<T> MaybeUninit<T> {
pub unsafe fn assume_init_read(&self) -> T { ... }
pub unsafe fn assume_init_drop(&mut self) { ... }
}
It does not cover the const-ness of `write` under
`const_maybe_uninit_write` nor the const-ness of
`assume_init_read` (this commit adds
`const_maybe_uninit_assume_init_read` for that).
FCP: https://github.com/rust-lang/rust/issues/63567#issuecomment-958590287.
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Replace usages of vec![].into_iter with [].into_iter
`[].into_iter` is idiomatic over `vec![].into_iter` because its simpler and faster (unless the vec is optimized away in which case it would be the same)
So we should change all the implementation, documentation and tests to use it.
I skipped:
* `src/tools` - Those are copied in from upstream
* `src/test/ui` - Hard to tell if `vec![].into_iter` was used intentionally or not here and not much benefit to changing it.
* any case where `vec![].into_iter` was used because we specifically needed a `Vec::IntoIter<T>`
* any case where it looked like we were intentionally using `vec![].into_iter` to test it.
Mak DefId to AccessLevel map in resolve for export
hir_id to accesslevel in resolve and applied in privacy
using local def id
removing tracing probes
making function not recursive and adding comments
Move most of Exported/Public res to rustc_resolve
moving public/export res to resolve
fix missing stability attributes in core, std and alloc
move code to access_levels.rs
return for some kinds instead of going through them
Export correctness, macro changes, comments
add comment for import binding
add comment for import binding
renmae to access level visitor, remove comments, move fn as closure, remove new_key
fmt
fix rebase
fix rebase
fmt
fmt
fix: move macro def to rustc_resolve
fix: reachable AccessLevel for enum variants
fmt
fix: missing stability attributes for other architectures
allow unreachable pub in rustfmt
fix: missing impl access level + renaming export to reexport
Missing impl access level was found thanks to a test in clippy
Fix a minor mistake in `String::try_reserve_exact` examples
The examples of `String::try_reserve_exact` didn't actually use `try_reserve_exact`, which was probably a minor mistake, and this PR fixed it.
Drop guards in slice sorting derive src pointers from &mut T, which is invalidated by interior mutation in comparison
I tried to run https://github.com/rust-lang/miri-test-libstd on `alloc` with `-Zmiri-track-raw-pointers`, and got a failure on the test `slice::panic_safe`. The test failure has nothing to do with panic safety, it's from how the test tests for panic safety.
I minimized the test failure into this very silly program:
```rust
use std::cell::Cell;
use std::cmp::Ordering;
#[derive(Clone)]
struct Evil(Cell<usize>);
fn main() {
let mut input = vec![Evil(Cell::new(0)); 3];
// Hits the bug pattern via CopyOnDrop in core
input.sort_unstable_by(|a, _b| {
a.0.set(0);
Ordering::Less
});
// Hits the bug pattern via InsertionHole in alloc
input.sort_by(|_a, b| {
b.0.set(0);
Ordering::Less
});
}
```
To fix this, I'm just removing the mutability/uniqueness where it wasn't required.
Implement split_at_spare_mut without Deref to a slice so that the spare slice is valid
~I'm not sure I understand what's going on here correctly. And I'm pretty sure this safety comment needs to be changed. I'm just referring to the same thing that `as_mut_ptr_range` does.~ (Thanks `@RalfJung` for the guidance and clearing things up)
I tried to run https://github.com/rust-lang/miri-test-libstd on alloc with -Zmiri-track-raw-pointers, and got a failure on the test `vec::test_extend_from_within`.
I minimized the test failure into this program:
```rust
#![feature(vec_split_at_spare)]
fn main() {
Vec::<i32>::with_capacity(1).split_at_spare_mut();
}
```
The problem is that the existing implementation is actually getting a pointer range where both pointers are derived from the initialized region of the Vec's allocation, but we need the second one to be valid for the region between len and capacity. (thanks Ralf for clearing this up)
RawVec: don't recompute capacity after allocating.
Currently it sets the capacity to `ptr.len() / mem::size_of::<T>()`
after any buffer allocation/reallocation. This would be useful if
allocators ever returned a `NonNull<[u8]>` with a size larger than
requested. But this never happens, so it's not useful.
Removing this slightly reduces the size of generated LLVM IR, and
slightly speeds up the hot path of `RawVec` growth.
r? `@ghost`
Allow reverse iteration of lowercase'd/uppercase'd chars
The PR implements `DoubleEndedIterator` trait for `ToLowercase` and `ToUppercase`.
This enables reverse iteration of lowercase/uppercase variants of character sequences.
One of use cases: determining whether a char sequence is a suffix of another one.
Example:
```rust
fn endswith_ignore_case(s1: &str, s2: &str) -> bool {
for eob in s1
.chars()
.flat_map(|c| c.to_lowercase())
.rev()
.zip_longest(s2.chars().flat_map(|c| c.to_lowercase()).rev())
{
match eob {
EitherOrBoth::Both(c1, c2) => {
if c1 != c2 {
return false;
}
}
EitherOrBoth::Left(_) => return true,
EitherOrBoth::Right(_) => return false,
}
}
true
}
```
Currently it sets the capacity to `ptr.len() / mem::size_of::<T>()`
after any buffer allocation/reallocation. This would be useful if
allocators ever returned a `NonNull<[u8]>` with a size larger than
requested. But this never happens, so it's not useful.
Removing this slightly reduces the size of generated LLVM IR, and
slightly speeds up the hot path of `RawVec` growth.
The previous implementation used slice::as_mut_ptr_range to derive the
pointer for the spare capacity slice. This is invalid, because that
pointer is derived from the initialized region, so it does not have
provenance over the uninitialized region.
Update example code for Vec::splice to change the length
The current example for `Vec::splice` illustrates the replacement of a section of length 2 with a new section of length 2. This isn't a particularly interesting case for splice, and makes it look a bit like a shorthand for the kind of manipulations that could be done with a mutable slice.
In order to provide a stronger example, this updates the example to use different lengths for the source and destination regions, and uses a slice from the middle of the vector to illustrate that this does not necessarily have to be at the beginning or the end.
Resolves#92067
The src pointers in CopyOnDrop and InsertionHole used to be *mut T, and
were derived via automatic conversion from &mut T. According to Stacked
Borrows 2.1, this means that those pointers become invalidated by
interior mutation in the comparison function.
But there's no need for mutability in this code path. Thus, we can
change the drop guards to use *const and derive those from &T.
Make split_inclusive() on an empty slice yield an empty output
`[].split_inclusive()` currently yields a single, empty slice. That's
different from `"".split_inslusive()`, which yields no output at
all. I think that makes the slice version harder to use.
The case where I ran into this bug was when writing code for
generating a diff between two slices of bytes. I wanted to prefix
removed lines with "-" and a added lines with "+". Due to
`split_inclusive()`'s current behavior, that means that my code prints
just a "-" or "+" for empty files. I suspect most existing callers
have similar "bugs" (which would be fixed by this patch).
Closes#89716.
add BinaryHeap::try_reserve and BinaryHeap::try_reserve_exact
`try_reserve` of many collections were stablized in https://github.com/rust-lang/rust/pull/87993 in 1.57.0. Add `try_reserve` for the rest collections such as `BinaryHeap` should be not controversial.
Use spare_capacity_mut instead of invalid unchecked indexing when joining str
This is a fix for https://github.com/rust-lang/rust/issues/91574
I think in general I'd prefer to see this code implemented with raw pointers or `MaybeUninit::write_slice`, but there's existing code in here based on copying from slice to slice, so converting everything from `&[T]` to `&[MaybeUninit<T>]` is less disruptive.
BTree: improve public descriptions and comments
BTreeSet has always used the term "value" next to and meaning the same thing as "elements" (in the mathematical sense but also used for key-value pairs in BTreeMap), while in the BTreeMap sense these "values" are known as "keys" and definitely not "values". Today I had enough of that.
r? `@Mark-Simulacrum`
Btree: assert more API compatibility
Introducing a member such as `BTreeSet::min()` would silently break compatibility if no code calls the existing `BTreeSet::min(set)`. `BTreeSet` is the only btree class silently bringing in stable members, apart from many occurrences of `#[derive(Debug)]` on iterators.
r? `@Mark-Simulacrum`
