Remove `#[rustc_deprecated]`
This removes `#[rustc_deprecated]` and introduces diagnostics to help users to the right direction (that being `#[deprecated]`). All uses of `#[rustc_deprecated]` have been converted. CI is expected to fail initially; this requires #95958, which includes converting `stdarch`.
I plan on following up in a short while (maybe a bootstrap cycle?) removing the diagnostics, as they're only intended to be short-term.
Mutex and Condvar are being replaced by more efficient implementations, which need thread parking themselves (see #93740). Therefore use the pthread synchronization primitives directly. Also, avoid allocating because the Parker struct is being placed in an Arc anyways.
Use modern formatting for format! macros
This updates the standard library's documentation to use the new format_args syntax.
The documentation is worthwhile to update as it should be more idiomatic
(particularly for features like this, which are nice for users to get acquainted
with). The general codebase is likely more hassle than benefit to update: it'll
hurt git blame, and generally updates can be done by folks updating the code if
(and when) that makes things more readable with the new format.
A few places in the compiler and library code are updated (mostly just due to
already having been done when this commit was first authored).
`eprintln!("{}", e)` becomes `eprintln!("{e}")`, but `eprintln!("{}", e.kind())` remains untouched.
This updates the standard library's documentation to use the new syntax. The
documentation is worthwhile to update as it should be more idiomatic
(particularly for features like this, which are nice for users to get acquainted
with). The general codebase is likely more hassle than benefit to update: it'll
hurt git blame, and generally updates can be done by folks updating the code if
(and when) that makes things more readable with the new format.
A few places in the compiler and library code are updated (mostly just due to
already having been done when this commit was first authored).
Remove argument from closure in thread::Scope::spawn.
This implements ```@danielhenrymantilla's``` [suggestion](https://github.com/rust-lang/rust/issues/93203#issuecomment-1040798286) for improving the scoped threads interface.
Summary:
The `Scope` type gets an extra lifetime argument, which represents basically its own lifetime that will be used in `&'scope Scope<'scope, 'env>`:
```diff
- pub struct Scope<'env> { .. };
+ pub struct Scope<'scope, 'env: 'scope> { .. }
pub fn scope<'env, F, T>(f: F) -> T
where
- F: FnOnce(&Scope<'env>) -> T;
+ F: for<'scope> FnOnce(&'scope Scope<'scope, 'env>) -> T;
```
This simplifies the `spawn` function, which now no longer passes an argument to the closure you give it, and now uses the `'scope` lifetime for everything:
```diff
- pub fn spawn<'scope, F, T>(&'scope self, f: F) -> ScopedJoinHandle<'scope, T>
+ pub fn spawn<F, T>(&'scope self, f: F) -> ScopedJoinHandle<'scope, T>
where
- F: FnOnce(&Scope<'env>) -> T + Send + 'env,
+ F: FnOnce() -> T + Send + 'scope,
- T: Send + 'env;
+ T: Send + 'scope;
```
The only difference the user will notice, is that their closure now takes no arguments anymore, even when spawning threads from spawned threads:
```diff
thread::scope(|s| {
- s.spawn(|_| {
+ s.spawn(|| {
...
});
- s.spawn(|s| {
+ s.spawn(|| {
...
- s.spawn(|_| ...);
+ s.spawn(|| ...);
});
});
```
<details><summary>And, as a bonus, errors get <em>slightly</em> better because now any lifetime issues point to the outermost <code>s</code> (since there is only one <code>s</code>), rather than the innermost <code>s</code>, making it clear that the lifetime lasts for the entire <code>thread::scope</code>.
</summary>
```diff
error[E0373]: closure may outlive the current function, but it borrows `a`, which is owned by the current function
--> src/main.rs:9:21
|
- 7 | s.spawn(|s| {
- | - has type `&Scope<'1>`
+ 6 | thread::scope(|s| {
+ | - lifetime `'1` appears in the type of `s`
9 | s.spawn(|| println!("{:?}", a)); // might run after `a` is dropped
| ^^ - `a` is borrowed here
| |
| may outlive borrowed value `a`
|
note: function requires argument type to outlive `'1`
--> src/main.rs:9:13
|
9 | s.spawn(|| println!("{:?}", a)); // might run after `a` is dropped
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to force the closure to take ownership of `a` (and any other referenced variables), use the `move` keyword
|
9 | s.spawn(move || println!("{:?}", a)); // might run after `a` is dropped
| ++++
"
```
</details>
The downside is that the signature of `scope` and `Scope` gets slightly more complex, but in most cases the user wouldn't need to write those, as they just use the argument provided by `thread::scope` without having to name its type.
Another downside is that this does not work nicely in Rust 2015 and Rust 2018, since in those editions, `s` would be captured by reference and not by copy. In those editions, the user would need to use `move ||` to capture `s` by copy. (Which is what the compiler suggests in the error.)
Add diagnostic items for macros
For use in Clippy, it adds diagnostic items to all the stable public macros
Clippy has lints that look for almost all of these (currently by name or path), but there are a few that aren't currently part of any lint, I could remove those if it's preferred to add them as needed rather than ahead of time
