Rollup of 4 pull requests #94718
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Rollup of 4 pull requests #94718
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Co-authored-by: Daniel Henry-Mantilla <daniel.henry.mantilla@gmail.com>
Co-authored-by: Mark Rousskov <mark.simulacrum@gmail.com>
Given
```rust
match Some(42) {}
```
suggest
```rust
match Some(42) { None | Some(_) => todo!(), }
```
…st it
Given
```rust
match Some(42) {
Some(0) => {}
}
```
suggest
```rust
match Some(42) {
Some(0) => {}
None | Some(_) => todo!(),
}
```
…est it
Given
```rust
match Some(42) {
Some(0) => {}
Some(1) => {}
}
```
suggest
```rust
match Some(42) {
Some(0) => {}
Some(1) => {}
None | Some(_) => todo!(),
}
```
… `span_label` This makes the order of the output always consistent: 1. Place of the `match` missing arms 2. The `enum` definition span 3. The structured suggestion to add a fallthrough arm
…li-obk Tweak output for non-exhaustive `match` expression * Provide structured suggestion when missing `match` arms * Move pointing at the missing variants *after* the main error <img width="1164" alt="" src="https://user-images.githubusercontent.com/1606434/146312085-b57ef4a3-6e96-4f32-aa2a-803637d9eeba.png">
Add Result::{ok, err, and, or, unwrap_or} as const
Already opened tracking issue rust-lang#92384.
I don't think that this should actually cause any issues as long as the constness is unstable, but we may want to double-check that this doesn't get interpreted as a weird `Drop` bound even for non-const usages.
…without-arg, r=Mark-Simulacrum Remove argument from closure in thread::Scope::spawn. This implements ``@danielhenrymantilla's`` [suggestion](rust-lang#93203 (comment)) 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.)
…sumption, r=Mark-Simulacrum promot debug_assert to assert Fixes rust-lang#94705
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@bors r+ rollup=never p=5 |
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📌 Commit cfed5de has been approved by |
bors
added
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S-waiting-on-bors
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⌛ Testing commit cfed5de with merge 9afe42c98dfb9a6366fe9a0ccf7f1526c8dce066... |
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💥 Test timed out |
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Successful merges:
matchexpression #91993 (Tweak output for non-exhaustivematchexpression)Failed merges:
r? @ghost
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