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
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
Add assert_matches macro.
This adds `assert_matches!(expression, pattern)`.
Unlike the other asserts, this one ~~consumes the expression~~ may consume the expression, to be able to match the pattern. (It could add a `&` implicitly, but that's noticable in the pattern, and will make a consuming guard impossible.)
See https://github.com/rust-lang/rust/issues/62633#issuecomment-790737853
This re-uses the same `left: .. right: ..` output as the `assert_eq` and `assert_ne` macros, but with the pattern as the right part:
assert_eq:
```
assertion failed: `(left == right)`
left: `Some("asdf")`,
right: `None`
```
assert_matches:
```
assertion failed: `(left matches right)`
left: `Ok("asdf")`,
right: `Err(_)`
```
cc ```@cuviper```
Add {BTreeMap,HashMap}::try_insert
`{BTreeMap,HashMap}::insert(key, new_val)` returns `Some(old_val)` if the key was already in the map. It's often useful to assert no duplicate values are inserted.
We experimented with `map.insert(key, val).unwrap_none()` (https://github.com/rust-lang/rust/issues/62633), but decided that that's not the kind of method we'd like to have on `Option`s.
`insert` always succeeds because it replaces the old value if it exists. One could argue that `insert()` is never the right method for panicking on duplicates, since already handles that case by replacing the value, only allowing you to panic after that already happened.
This PR adds a `try_insert` method that instead returns a `Result::Err` when the key already exists. This error contains both the `OccupiedEntry` and the value that was supposed to be inserted. This means that unwrapping that result gives more context:
```rust
map.insert(10, "world").unwrap_none();
// thread 'main' panicked at 'called `Option::unwrap_none()` on a `Some` value: "hello"', src/main.rs:8:29
```
```rust
map.try_insert(10, "world").unwrap();
// thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value:
// OccupiedError { key: 10, old_value: "hello", new_value: "world" }', src/main.rs:6:33
```
It also allows handling the failure in any other way, as you have full access to the `OccupiedEntry` and the value.
`try_insert` returns a reference to the value in case of success, making it an alternative to `.entry(key).or_insert(value)`.
r? ```@Amanieu```
Fixes https://github.com/rust-lang/rfcs/issues/3092
Avoid unnecessary Vec construction in BufReader
As mentioned in #80460, creating a `Vec` and calling `Vec::into_boxed_slice()` emits unnecessary calls to `realloc()` and `free()`. Updated the code to use `Box::new_uninit_slice()` to create a boxed slice directly. I think this also makes it more explicit that the initial contents of the buffer are uninitialized.
r? ``@m-ou-se``
Improved IO Bytes Size Hint
After trying to implement better `size_hint()` return values for `File` in [this PR](https://github.com/rust-lang/rust/pull/81044) and changing to implementing it for `BufReader` in [this PR](https://github.com/rust-lang/rust/pull/81052), I have arrived at this implementation that provides tighter bounds for the `Bytes` iterator of various readers including `BufReader`, `Empty`, and `Chain`.
Unfortunately, for `BufReader`, the size_hint only improves after calling `fill_buffer` due to it using the contents of the buffer for the hint. Nevertheless, the the tighter bounds should result in better pre-allocation of space to handle the contents of the `Bytes` iterator.
Closes#81052
Implement NOOP_METHOD_CALL lint
Implements the beginnings of https://github.com/rust-lang/lang-team/issues/67 - a lint for detecting noop method calls (e.g, calling `<&T as Clone>::clone()` when `T: !Clone`).
This PR does not fully realize the vision and has a few limitations that need to be addressed either before merging or in subsequent PRs:
* [ ] No UFCS support
* [ ] The warning message is pretty plain
* [ ] Doesn't work for `ToOwned`
The implementation uses [`Instance::resolve`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/instance/struct.Instance.html#method.resolve) which is normally later in the compiler. It seems that there are some invariants that this function relies on that we try our best to respect. For instance, it expects substitutions to have happened, which haven't yet performed, but we check first for `needs_subst` to ensure we're dealing with a monomorphic type.
Thank you to ```@davidtwco,``` ```@Aaron1011,``` and ```@wesleywiser``` for helping me at various points through out this PR ❤️.
unix: Non-mutable bufs in send_vectored_with_ancillary_to
This is the same PR as [#79753](https://github.com/rust-lang/rust/pull/79753). It was closed because of inactivity. Therefore, I create a new one. ````@lukaslihotzki````
Add is_enclave_range/is_user_range overflow checks
Fixes#76343.
This adds overflow checking to `is_enclave_range` and `is_user_range` in `sgx::os::fortanix_sgx::mem` in order to mitigate possible security issues with enclave code. It also accounts for an edge case where the memory range provided ends exactly at the end of the address space, where calculating `p + len` would overflow back to zero despite the range potentially being valid.
Convert primitives in the standard library to intra-doc links
Blocked on https://github.com/rust-lang/rust/pull/80181. I forgot that this needs to wait for the beta bump so the standard library can be documented with `doc --stage 0`.
Notably I didn't convert `core::slice` because it's like 50 links and I got scared 😨
Clarify that SyncOnceCell::set blocks.
Reading the discussion of this feature, I gained the mistaken impression that neither `set` nor `get` blocked, and thus calling `get` immediately after `set` was not guaranteed to succeed. It turns out that `set` *does* block, guaranteeing that the cell contains a value once `set` returns. This change updates the documentation to state that explicitly.
Happy to adjust the wording as desired.
Reading the discussion of this feature, I gained the mistaken impression that neither `set` nor `get` blocked, and thus calling `get` immediately after `set` was not guaranteed to succeed. It turns out that `set` *does* block, guaranteeing that the cell contains a value once `set` returns. This change updates the documentation to state that explicitly.
Remove the x86_64-rumprun-netbsd target
Herein we remove the target from the compiler and the code from libstd intended to support the now-defunct rumprun project.
Closes#81514
clarify RW lock's priority gotcha
In particular, the following program works on Linux, but deadlocks on
mac:
```rust
use std::{
sync::{Arc, RwLock},
thread,
time::Duration,
};
fn main() {
let lock = Arc::new(RwLock::new(()));
let r1 = thread::spawn({
let lock = Arc::clone(&lock);
move || {
let _rg = lock.read();
eprintln!("r1/1");
sleep(1000);
let _rg = lock.read();
eprintln!("r1/2");
sleep(5000);
}
});
sleep(100);
let w = thread::spawn({
let lock = Arc::clone(&lock);
move || {
let _wg = lock.write();
eprintln!("w");
}
});
sleep(100);
let r2 = thread::spawn({
let lock = Arc::clone(&lock);
move || {
let _rg = lock.read();
eprintln!("r2");
sleep(2000);
}
});
r1.join().unwrap();
r2.join().unwrap();
w.join().unwrap();
}
fn sleep(ms: u64) {
std:🧵:sleep(Duration::from_millis(ms))
}
```
Context: I was completely mystified by a my CI deadlocking on mac ([here](https://github.com/matklad/xshell/pull/7)), until ``@azdavis`` debugged the issue. See a stand-alone reproduciton here: https://github.com/matklad/xshell/pull/15
Add missing "see its documentation for more" stdio
StdoutLock and StderrLock does not have example, it would be better
to leave "see its documentation for more" like iter docs.
In particular, the following program works on Linux, but deadlocks on
mac:
use std::{
sync::{Arc, RwLock},
thread,
time::Duration,
};
fn main() {
let lock = Arc::new(RwLock::new(()));
let r1 = thread::spawn({
let lock = Arc::clone(&lock);
move || {
let _rg = lock.read();
eprintln!("r1/1");
sleep(1000);
let _rg = lock.read();
eprintln!("r1/2");
sleep(5000);
}
});
sleep(100);
let w = thread::spawn({
let lock = Arc::clone(&lock);
move || {
let _wg = lock.write();
eprintln!("w");
}
});
sleep(100);
let r2 = thread::spawn({
let lock = Arc::clone(&lock);
move || {
let _rg = lock.read();
eprintln!("r2");
sleep(2000);
}
});
r1.join().unwrap();
r2.join().unwrap();
w.join().unwrap();
}
fn sleep(ms: u64) {
std:🧵:sleep(Duration::from_millis(ms))
}
Use libc::accept4 on Android instead of raw syscall.
This PR replaces the use of a raw `accept4` syscall with `libc::accept4`. This was originally added (by me) because `std` couldn't update to the latest `libc` with `accept4` support for android. By now, libc is already on 0.2.85, so the workaround can be removed.
`@rustbot` label +O-android +T-libs-impl
Add a `size()` function to WASI's `MetadataExt`.
WASI's `filestat` type includes a size field, so expose it in
`MetadataExt` via a `size()` function, similar to the corresponding Unix
function.
r? ``````@alexcrichton``````
Enable API documentation for `std::os::wasi`.
This adds API documentation support for `std::os::wasi` modeled after
how `std::os::unix` works, so that WASI can be documented [here] along
with the other platforms.
[here]: https://doc.rust-lang.org/stable/std/os/index.html
Two changes of particular interest:
- This changes the `AsRawFd` for `io::Stdin` for WASI to return
`libc::STDIN_FILENO` instead of `sys::stdio::Stdin.as_raw_fd()` (and
similar for `Stdout` and `Stderr`), which matches how the `unix`
version works. `STDIN_FILENO` etc. may not always be explicitly
reserved at the WASI level, but as long as we have Rust's `std` and
`libc`, I think it's reasonable to guarantee that we'll always use
`libc::STDIN_FILENO` for stdin.
- This duplicates the `osstr2str` utility function, rather than
trying to share it across all the configurations that need it.
r? ```@alexcrichton```
library: Normalize safety-for-unsafe-block comments
Almost all safety comments are of the form `// SAFETY:`,
so normalize the rest and fix a few of them that should
have been a `/// # Safety` section instead.
Furthermore, make `tidy` only allow the uppercase form. While
currently `tidy` only checks `core`, it is a good idea to prevent
`core` from drifting to non-uppercase comments, so that later
we can start checking `alloc` etc. too.
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
