std: Fix a bug on the wasm32-wasi target opening files
This commit fixes an issue pointed out in #82758 where LTO changed the
behavior of a program. It turns out that LTO was not at fault here, it
simply uncovered an existing bug. The bindings to
`__wasilibc_find_relpath` assumed that the relative portion of the path
returned was always contained within thee input `buf` we passed in. This
isn't actually the case, however, and sometimes the relative portion of
the path may reference a sub-portion of the input string itself.
The fix here is to use the relative path pointer coming out of
`__wasilibc_find_relpath` as the source of truth. The `buf` used for
local storage is discarded in this function and the relative path is
copied out unconditionally. We might be able to get away with some
`Cow`-like business or such to avoid the extra allocation, but for now
this is probably the easiest patch to fix the original issue.
Implement Extend and FromIterator for OsString
Add the following trait impls:
- `impl Extend<OsString> for OsString`
- `impl<'a> Extend<&'a OsStr> for OsString`
- `impl FromIterator<OsString> for OsString`
- `impl<'a> FromIterator<&'a OsStr> for OsString`
Because `OsString` is a platform string with no particular semantics, concatenating them together seems acceptable.
I came across a use case for these trait impls in https://github.com/artichoke/artichoke/pull/1089:
Artichoke is a Ruby interpreter. Its CLI accepts multiple `-e` switches for executing inline Ruby code, like:
```console
$ cargo -q run --bin artichoke -- -e '2.times {' -e 'puts "foo: #{__LINE__}"' -e '}'
foo: 2
foo: 2
```
I use `clap` for command line argument parsing, which collects these `-e` commands into a `Vec<OsString>`. To pass these commands to the interpreter for `Eval`, I need to join them together. Combining these impls with `Iterator::intersperse` https://github.com/rust-lang/rust/issues/79524 would enable me to build a single bit of Ruby code.
Currently, I'm doing something like:
```rust
let mut commands = commands.into_iter();
let mut buf = if let Some(command) = commands.next() {
command
} else {
return Ok(Ok(()));
};
for command in commands {
buf.push("\n");
buf.push(command);
}
```
If there's interest, I'd also like to add impls for `Cow<'a, OsStr>`, which would avoid allocating the `"\n"` `OsString` in the concatenate + intersperse use case.
Don't implement mem::replace with mem::swap.
`swap` is a complicated operation, so this changes the implementation of `replace` to use `read` and `write` instead.
See https://github.com/rust-lang/rust/pull/83019.
I wrote there:
> Implementing the simpler operation (replace) with the much more complicated operation (swap) doesn't make a whole lot of sense. `replace` is just read+write, and the primitive for moving out of a `&mut`. `swap` is for doing that to *two* `&mut` at the same time, which is both more niche and more complicated (as shown by `swap_nonoverlapping_bytes`).
This could be especially interesting for `Option<VeryLargeStruct>::take()`, since swapping such a large structure with `swap_nonoverlapping_bytes` is going to be much less efficient than `ptr::write()`'ing a `None`.
But also for small values where `swap` just reads/writes using temporary variable, this makes a `replace` or `take` operation simpler:
Rollup of 11 pull requests
Successful merges:
- #80385 (Clarify what `Cell::replace` returns)
- #82571 (Rustdoc Json: Add tests for Reexports, and improve jsondocck)
- #82860 (Add `-Z unpretty` flag for the THIR)
- #82950 (convert slice doc link to intra-doc links)
- #82965 (Add spirv extension handling in compiletest)
- #82966 (update MSYS2 link in README)
- #82979 (Fix "run" button position in error index)
- #83001 (Ignore Vim swap files)
- #83003 (rustdoc: tweak the search index format)
- #83013 (Adjust some `#[cfg]`s to take non-Unix non-Windows operating systems into account)
- #83018 (Reintroduce accidentally deleted assertions.)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
convert slice doc link to intra-doc links
Continuing where #80189 stopped, with `core::slice`.
I had an issue with two dead links in my doc when implementing `Deref<Target = [T]>` for one of my type. This means that [`binary_search_by_key`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.binary_search_by_key) was available, but not [`sort_by_key`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.sort_by_key) even though it was linked in it's doc (same issue with [`as_ptr`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.as_ptr) and [`as_mut_pbr`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.as_mut_ptr)). It becomes available if I implement `DerefMut`, as it needs an `&mut self`.
<details>
<summary>Code that will have dead links in its doc</summary>
```rust
pub struct A;
pub struct B;
impl std::ops::Deref for B{
type Target = [A];
fn deref(&self) -> &Self::Target {
&A
}
}
```
</details>
I removed the link to `sort_by_key` from `binary_search_by_key` doc as I didn't find a nice way to have a live link:
- `binary_search_by_key` is in `core`
- `sort_by_key` is in `alloc`
- intra-doc link `slice::sort_by_key` doesn't work, as `alloc` is not available when `core` is being build (the warning can't be ignored: ```error[E0710]: an unknown tool name found in scoped lint: `rustdoc::broken_intra_doc_links` ```)
- keeping the link as an anchor `#method.sort_by_key` meant a dead link
- an absolute link would work but doesn't feel right...
Fix io::copy specialization using copy_file_range when writer was opened with O_APPEND
fixes#82410
While `sendfile()` returns `EINVAL` when the output was opened with O_APPEND, `copy_file_range()` does not and returns `EBADF` instead, which – unlike other `EBADF` causes – is not fatal for this operation since a regular `write()` will likely succeed.
We now treat `EBADF` as a non-fatal error for `copy_file_range` and fall back to a read-write copy as we already did for several other errors.
Do not attempt to unlock envlock in child process after a fork.
This implements the first two points from https://github.com/rust-lang/rust/issues/64718#issuecomment-793030479
This is a breaking change for cases where the environment is accessed in a Command::pre_exec closure. Except for single-threaded programs these uses were not correct anyway since they aren't async-signal safe.
Note that we had a ui test that explicitly tried `env::set_var` in `pre_exec`. As expected it failed with these changes when I tested locally.
Edition-specific preludes
This changes `{std,core}::prelude` to export edition-specific preludes under `rust_2015`, `rust_2018` and `rust_2021`. (As suggested in https://github.com/rust-lang/rust/issues/51418#issuecomment-395630382.) For now they all just re-export `v1::*`, but this allows us to add things to the 2021edition prelude soon.
This also changes the compiler to make the automatically injected prelude import dependent on the selected edition.
cc `@rust-lang/libs` `@djc`
Add Option::get_or_default
Tracking issue: #82901
The original issue is #55042, which was closed, but for an invalid reason (see discussion there). Opening this to reconsider (I hope that's okay). It seems like the only gap for `Option` being "entry-like".
I ran into a need for this method where I had a `Vec<Option<MyData>>` and wanted to do `vec[n].get_or_default().my_data_method()`. Using an `Option` as an inner component of a data structure is probably where the need for this will normally arise.
Fixes to ExitStatus and its docs
* On Unix, properly display every possible wait status (and don't panic on weird values)
* In the documentation, be clear and consistent about "exit status" vs "wait status".
Stabilize `unsafe_op_in_unsafe_fn` lint
This makes it possible to override the level of the `unsafe_op_in_unsafe_fn`, as proposed in https://github.com/rust-lang/rust/issues/71668#issuecomment-729770896.
Tracking issue: #71668
r? ```@nikomatsakis``` cc ```@SimonSapin``` ```@RalfJung```
# Stabilization report
This is a stabilization report for `#![feature(unsafe_block_in_unsafe_fn)]`.
## Summary
Currently, the body of unsafe functions is an unsafe block, i.e. you can perform unsafe operations inside.
The `unsafe_op_in_unsafe_fn` lint, stabilized here, can be used to change this behavior, so performing unsafe operations in unsafe functions requires an unsafe block.
For now, the lint is allow-by-default, which means that this PR does not change anything without overriding the lint level.
For more information, see [RFC 2585](https://github.com/rust-lang/rfcs/blob/master/text/2585-unsafe-block-in-unsafe-fn.md)
### Example
```rust
// An `unsafe fn` for demonstration purposes.
// Calling this is an unsafe operation.
unsafe fn unsf() {}
// #[allow(unsafe_op_in_unsafe_fn)] by default,
// the behavior of `unsafe fn` is unchanged
unsafe fn allowed() {
// Here, no `unsafe` block is needed to
// perform unsafe operations...
unsf();
// ...and any `unsafe` block is considered
// unused and is warned on by the compiler.
unsafe {
unsf();
}
}
#[warn(unsafe_op_in_unsafe_fn)]
unsafe fn warned() {
// Removing this `unsafe` block will
// cause the compiler to emit a warning.
// (Also, no "unused unsafe" warning will be emitted here.)
unsafe {
unsf();
}
}
#[deny(unsafe_op_in_unsafe_fn)]
unsafe fn denied() {
// Removing this `unsafe` block will
// cause a compilation error.
// (Also, no "unused unsafe" warning will be emitted here.)
unsafe {
unsf();
}
}
```
This is a breaking change for cases where the environment is
accessed in a Command::pre_exec closure. Except for
single-threaded programs these uses were not correct
anyway since they aren't async-signal safe.
Bump libc dependency of std to 0.2.88.
This PR bumps the `libc` dependency of `std` to 0.2.88. This will fix `TcpListener::accept` for Android on x86 platforms (31a2777d8f).
This will really finally fix https://github.com/rust-lang/rust/issues/82400 for the main branch :)
r? ``@JohnTitor``
Added #[repr(transparent)] to core::cmp::Reverse
I found casting from an `&T` to an `&Reverse<T>` potentially useful, but found that `Reverse` was not `#[repr(transparent)]`, so after asking about it [on Reddit](https://www.reddit.com/r/rust/comments/le60uv/make_stdcmpreverse_reprtransparent_and_add_a/), I decided to go ahead and make a pull request which simply adds the attribute to the struct.
Improve sift_down performance in BinaryHeap
Replacing `child < end - 1` with `child <= end.saturating_sub(2)` in `BinaryHeap::sift_down_range` (surprisingly) results in a significant speedup of `BinaryHeap::into_sorted_vec`. The same substitution can be done for `BinaryHeap::sift_down_to_bottom`, which causes a slight but probably statistically insignificant speedup for `BinaryHeap::pop`. It's interesting that benchmarks aside from `bench_into_sorted_vec` are barely affected, even those that do use `sift_down_*` methods internally.
| Benchmark | Before (ns/iter) | After (ns/iter) | Speedup |
|--------------------------|------------------|-----------------|---------|
| bench_find_smallest_1000<sup>1</sup> | 392,617 | 385,200 | 1.02 |
| bench_from_vec<sup>1</sup> | 506,016 | 504,444 | 1.00 |
| bench_into_sorted_vec<sup>1</sup> | 476,869 | 384,458 | 1.24 |
| bench_peek_mut_deref_mut<sup>3</sup> | 518,753 | 519,792 | 1.00 |
| bench_pop<sup>2</sup> | 446,718 | 444,409 | 1.01 |
| bench_push<sup>3</sup> | 772,481 | 770,208 | 1.00 |
<sup>1</sup>: internally calls `sift_down_range`
<sup>2</sup>: internally calls `sift_down_to_bottom`
<sup>3</sup>: should not be affected
Revert switch of env locking to rwlock, to fix deadlock in process spawning
This reverts commit 354f19cf24, reversing changes made to 0cfba2fd09.
PR https://github.com/rust-lang/rust/pull/81850 switched the environment lock from a mutex to an rwlock. However, process spawning (when not able to use `posix_spawn`) locks the environment before forking, and unlocks it after forking (in both the parent and the child). With a mutex, this works (although probably not correct even with a mutex). With an rwlock, on at least some targets, unlocking in the child does not work correctly, resulting in a deadlock.
This has manifested as CI hangs on i686 Linux; that target doesn't use `posix_spawn` in the CI environment due to the age of the installed C library (currently glibc 2.23). (Switching to `posix_spawn` would just mask this issue, though, which would still arise in any case that can't use `posix_spawn`.)
Some additional cleanup of environment handling around process spawning may help, but for now, revert the PR and go back to a standard mutex.
Fixes#82221
Add note about the `#[doc(no-inline)]` usage
This is required to correctly build the documentation (including all submodules, that are only available in certain targets).
See the linked issue and #82861 for reference.
Generalize Write impl for Vec<u8> to Vec<u8, A>
As discussed in the [issue tracker for the wg-allocators working group][1], updating this impl for allocator support was most likely just forgotten previously. This PR fixes this.
r? `````@TimDiekmann`````
[1]: https://github.com/rust-lang/wg-allocators/issues/86
Implement built-in attribute macro `#[cfg_eval]` + some refactoring
This PR implements a built-in attribute macro `#[cfg_eval]` as it was suggested in https://github.com/rust-lang/rust/pull/79078 to avoid `#[derive()]` without arguments being abused as a way to configure input for other attributes.
The macro is used for eagerly expanding all `#[cfg]` and `#[cfg_attr]` attributes in its input ("fully configuring" the input).
The effect is identical to effect of `#[derive(Foo, Bar)]` which also fully configures its input before passing it to macros `Foo` and `Bar`, but unlike `#[derive]` `#[cfg_eval]` can be applied to any syntax nodes supporting macro attributes, not only certain items.
`cfg_eval` was the first name suggested in https://github.com/rust-lang/rust/pull/79078, but other alternatives are also possible, e.g. `cfg_expand`.
```rust
#[cfg_eval]
#[my_attr] // Receives `struct S {}` as input, the field is configured away by `#[cfg_eval]`
struct S {
#[cfg(FALSE)]
field: u8,
}
```
Tracking issue: https://github.com/rust-lang/rust/issues/82679
As discussed in the issue tracker for the wg-allocators working group[1], updating this implementation for allocator support was most likely just forgotten in the original PR.
[1]: https://github.com/rust-lang/wg-allocators/issues/86
improve offset_from docs
`@thomcc` pointed out that the current docs leave it kind of unclear how one can satisfy the "no wrapping around `isize` or the address space" requirement of `offset_from`, so make the docs clearer about that.
FWIW, I don't think I entirely agree with that second paragraph about large objects (that I left mostly unchanged here). LLVM, to my knowledge, fundamentally assumes that all allocations fit into an `isize::MAX`. So in that sense creating a larger allocation is simply UB. I would expect a guarantee that Rust heap allocation methods will never return allocations larger than `isize::MAX` (or rather, Rust heap allocation methods should require that the `Layout` is no larger than `isize::MAX`). However, I cannot find any such requirement documented currently. Large allocations are not mentioned at all in the allocator docs, which is quite surprising -- even if we say that such allocations are not insta-UB (which I think is incompatible with LLVM), they are still extremely footgunny since `ptr::offset`/`ptr::add` do not support offsetting by more than `isize::MAX` bytes.
Furthermore, the allocator docs don't even say anything about allocations wrapping around the address space. But that is certainly something allocators must ensure never happens; we cannot expect clients to defend against this.
Cc `@rust-lang/wg-allocators`
Improve transmute docs with further clarifications
Closes#82493.
Please let me know if any of the new wording sounds off, English is not my mother tongue.
Prevent specialized ZipImpl from calling `__iterator_get_unchecked` twice with the same index
Fixes#82291
It's open for review, but conflicts with #82289, wait before merging. The conflict involves only the new test, so it should be rather trivial to fix.
Make some Option, Result methods unstably const
The following methods are now unstably const:
- Option::transpose
- Option::flatten
- Result::flatten
While some methods for could likely be made `const` in the future, nearly all of them require something to be dropped at compile-time, which isn't currently supported. The functions listed above should have a trivial path to stabilization.
Change built-in kernel targets to be os = none throughout
Whether for Rust's own `target_os`, LLVM's triples, or GNU config's, the
OS-related have fields have been for code running *on* that OS, not code
hat is *part* of the OS.
The difference is huge, as syscall interfaces are nothing like
freestanding interfaces. Kernels are (hypervisors and other more exotic
situations aside) freestanding programs that use the interfaces provided
by the hardware. It's *those* interfaces, the ones external to the
program being built and its software dependencies, that are the content
of the target.
For the Linux Kernel in particular, `target_env: "gnu"` is removed for
the same reason: that `-gnu` refers to glibc or GNU/linux, neither of
which applies to the kernel itself.
Relates to #74247
