Mention that std::fs::remove_dir_all fails on files
This is explicitly mentioned for std::fs::remove_file.
It is more likely for a slightly lazy programmer to believe that removing a file would work and that they do not have to distinguish between directories (with contents) and files themself, because of the function's recursive nature and how it distinguishes between files and directories when removing them.
Follow-up for #133183.
std: allow after-main use of synchronization primitives
By creating an unnamed thread handle when the actual one has already been destroyed, synchronization primitives using thread parking can be used even outside the Rust runtime.
This also fixes an inefficiency in the queue-based `RwLock`: if `thread::current` was not initialized yet, it will create a new handle on every parking attempt without initializing `thread::current`. The private `current_or_unnamed` function introduced here fixes this.
Add `AsyncFn*` to the prelude in all editions
The general vibe is that we will most likely stabilize the `feature(async_closure)` *without* the `async Fn()` trait bound modifier.
Without `async Fn()` bound syntax, this necessitates users to spell the bound like `AsyncFn()`. Since `core::ops::AsyncFn` is not in the prelude, users will need to import these any time they actually want to use the trait. This seems annoying, so let's add these traits to the prelude unstably.
We're trying to work on the general vision of `async` trait bound modifier in general in: https://github.com/rust-lang/rfcs/pull/3710, however that RFC still needs more time for consensus to converge, and we've decided that the value that users get from calling the bound `async Fn()` is *not really* worth blocking landing async closures in general.
This is explicitly mentioned for std::fs::remove_file's documentation,
but not in the aforementioned function.
It is more likely for a slightly lazy programmer to believe that
removing a file would work and that they do not have to distinguish
between directories (with contents) and files themself, because of the
function's recursive nature and how it distinguishes between files and
directories when removing them.
Emscripten: link with -sWASM_BIGINT
When linking an executable without dynamic linking, this is a pure improvement. It significantly reduces code size and avoids a lot of buggy behaviors. It is supported in all browsers for many years and in all maintained versions of Node.
It does change the ABI, so people who are dynamically linking with a library or executable that uses the old ABI may need to turn it off. It can be disabled if needed by passing `-Clink-arg -sWASM_BIGINT=0` to `rustc`. But few people will want to turn it off.
Note this includes a libc bump to 0.2.162!
Mark `get_mut` and `set_position` in `std::io::Cursor` as const.
Relevant tracking issue: #130801
The methods `get_mut` and `set_position` can trivially be marked as const due to #57349 being stabilised.
Rollup of 4 pull requests
Successful merges:
- #131081 (Use `ConstArgKind::Path` for all single-segment paths, not just params under `min_generic_const_args`)
- #132577 (Report the `unexpected_cfgs` lint in external macros)
- #133023 (Merge `-Zhir-stats` into `-Zinput-stats`)
- #133200 (ignore an occasionally-failing test in Miri)
r? `@ghost`
`@rustbot` modify labels: rollup
Improve `{BTreeMap,HashMap}::get_key_value` docs.
They are unusual methods. The docs don't really describe the cases when they might be useful (as opposed to just `get`), and the examples don't demonstrate the interesting cases at all.
This commit improves the docs and the examples.
By creating an unnamed thread handle when the actual one has already been destroyed, synchronization primitives using thread parking can be used even outside the Rust runtime.
This also fixes an inefficiency in the queue-based `RwLock`: if `thread::current` was not initialized yet, it will create a new handle on every parking attempt without initializing `thread::current`. The private `current_or_unnamed` function introduced here fixes this.
Rwlock downgrade
Tracking Issue: #128203
This PR adds a `downgrade` method for `RwLock` / `RwLockWriteGuard` on all currently supported platforms.
Outstanding questions:
- [x] ~~Does the `futex.rs` change affect performance at all? It doesn't seem like it will but we can't be certain until we bench it...~~
- [x] ~~Should the SOLID platform implementation [be ported over](https://github.com/rust-lang/rust/pull/128219#discussion_r1693470090) to the `queue.rs` implementation to allow it to support downgrades?~~
They are unusual methods. The docs don't really describe the cases when
they might be useful (as opposed to just `get`), and the examples don't
demonstrate the interesting cases at all.
This commit improves the docs and the examples.
This commit fixes a memory ordering bug in the futex implementation
(`Relaxed` -> `Release` on `downgrade`).
This commit also removes a badly written test that deadlocked and
replaces it with a more reasonable test based on an already-tested
`downgrade` test from the parking-lot crate.
This commit adds the `downgrade` method onto the inner `RwLock` queue
implementation.
There are also a few other style patches included in this commit.
Co-authored-by: Jonas Böttiger <jonasboettiger@icloud.com>
This commit only has documentation changes and a few things moved around
the file. The very few code changes are cosmetic: changes like turning a
`match` statement into an `if let` statement or reducing indentation for
long if statements.
This commit also adds several safety comments on top of `unsafe` blocks
that might not be immediately obvious to a first-time reader.
Code "changes" are in:
- `add_backlinks_and_find_tail`
- `lock_contended`
A majority of the changes are just expanding the comments from 80
columns to 100 columns.
