This was essentially a "query" previously (with no key, just always run
once when resolving the crate dependencies), and remains so, just now in
a way that isn't on Session. This removes the need for the `Once` as
well.
Use ptr::drop_in_place for VecDeque::truncate and VecDeque::clear
This commit allows `VecDeque::truncate` to take advantage of its (largely) contiguous memory layout and is consistent with the change in #64432 for `Vec`. As with the change to `Vec::truncate`, this changes both:
- the drop order, from back-to-front to front-to-back
- the behavior when dropping an element panics
For consistency, it also changes the behavior when dropping an element panics for `VecDeque::clear`.
These changes in behavior can be observed. This example ([playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=d0b1f2edc123437a2f704cbe8d93d828))
```rust
use std::collections::VecDeque;
fn main() {
struct Bomb(usize);
impl Drop for Bomb {
fn drop(&mut self) {
panic!(format!("{}", self.0));
}
}
let mut v = VecDeque::from(vec![Bomb(0), Bomb(1)]);
std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
v.truncate(0);
}));
std::mem::forget(v);
}
```
panics printing `1` today and succeeds. `v.clear()` panics printing `0` today and succeeds. With the change, `v.clear()`, `v.truncate(0)`, and dropping the `VecDeque` all panic printing `0` first and then abort with a double-panic printing `1`.
The motivation for this was making `VecDeque::truncate` more efficient since it was used in the implementation of `VecDeque::clone_from` (#65069), but it also makes behavior more consistent within the `VecDeque` and with `Vec` if that change is accepted (this probably doesn't make sense to merge if not).
This might need a crater run and an FCP as well.
Merge repeated definitions
Step forward on #66149
I may need further context to understand the need for a separate crate.
Also, please tell me if you think of other definitions to merge.
Make error and warning annotations mandatory in UI tests
This change makes error and warning annotations mandatory in UI tests.
The only exception are tests that use error patterns to match compiler
output and don't have any annotations.
Fixes#55596.
Consider this example: small_set = 0..2, large_set = 0..1000.
To efficiently compute the union of these sets, we should
* take all elements of the larger set
* for each element of the smaller set check it is not in the larger set
This is exactly what this commit does.
This particular optimization was implemented a year ago, but the
author mistaken `<` and `>`.
This change makes error and warning annotations mandatory in UI tests.
The only exception are tests that use error patterns to match compiler
output and don't have any annotations.
Support registering inert attributes and attribute tools using crate-level attributes
And remove `#[feature(custom_attribute)]`.
(`rustc_plugin::Registry::register_attribute` is not removed yet, I'll do it in a follow up PR.)
```rust
#![register_attr(my_attr)]
#![register_tool(my_tool)]
#[my_attr] // OK
#[my_tool::anything] // OK
fn main() {}
```
---
Some tools (`rustfmt` and `clippy`) used in tool attributes are hardcoded in the compiler.
We need some way to introduce them without hardcoding as well.
This PR introduces a way to do it with a crate level attribute.
The previous attempt to introduce them through command line (https://github.com/rust-lang/rust/pull/57921) met some resistance.
This probably needs to go through an RFC before stabilization.
However, I'd prefer to land *this* PR without an RFC to able to remove `#[feature(custom_attribute)]` and `Registry::register_attribute` while also providing a replacement.
---
`register_attr` is a direct replacement for `#![feature(custom_attribute)]` (https://github.com/rust-lang/rust/issues/29642), except it doesn't rely on implicit fallback from unresolved attributes to custom attributes (which was always hacky and is the primary reason for the removal of `custom_attribute`) and requires registering the attribute explicitly.
It's not clear whether it should go through stabilization or not.
It's quite possible that all the uses should migrate to `#![register_tool]` (https://github.com/rust-lang/rust/issues/66079) instead.
---
Details:
- The naming is `register_attr`/`register_tool` rather than some `register_attributes` (plural, no abbreviation) for consistency with already existing attributes like `cfg_attr`, or `feature`, etc.
---
Previous attempt: https://github.com/rust-lang/rust/pull/57921
cc https://github.com/rust-lang/rust/issues/44690
Tracking issues: #66079 (`register_tool`), #66080 (`register_attr`)
Closes https://github.com/rust-lang/rust/issues/29642
