rustfmt libarena/lib.rs
Note: it's my very first pull request. I'm trying to do something very simple to see how it works here, even if it's a tiny change or maybe it's not correct (sorry if it is the case).
r? @nrc
macros: improve 1.0/2.0 interaction
This PR supports using unhygienic macros from hygienic macros without breaking the latter's hygiene.
```rust
// crate A:
#[macro_export]
macro_rules! m1 { () => {
f(); // unhygienic: this macro needs `f` in its environment
fn g() {} // (1) unhygienic: `g` is usable outside the macro definition
} }
// crate B:
#![feature(decl_macro)]
extern crate A;
use A::m1;
macro m2() {
fn f() {} // (2)
m1!(); // After this PR, `f()` in the expansion resolves to (2), not (3)
g(); // After this PR, this resolves to `fn g() {}` from the above expansion.
// Today, it is a resolution error.
}
fn test() {
fn f() {} // (3)
m2!(); // Today, `m2!()` can see (3) even though it should be hygienic.
fn g() {} // Today, this conflicts with `fn g() {}` from the expansion, even though it should be hygienic.
}
```
Once this PR lands, you can make an existing unhygienic macro hygienic by wrapping it in a hygienic macro. There is an [example](b766fa887d) of this in the tests.
r? @nrc
Add iterator method specialisations to Range*
Add specialised implementations of `max` for `Range`, and `last`, `min` and `max` for `RangeInclusive`, all of which lead to significant advantages in the generated assembly on x86.
Note that adding specialisations of `min` and `last` for `Range` led to no benefit, and adding `sum` for `Range` and `RangeInclusive` led to type inference issues (though this is possibly still worthwhile considering the performance gain).
This addresses some of the concerns in #39975.
Replace uses of DepGraph.in_ignore with DepGraph.with_ignore
I currently plan to track tasks in thread local storage. Ignoring things in a closure ensures that the ignore tasks do not overlap the beginning or end of any other task. The TLS API will also use a closure to change a TLS value, so having the ignore task be a closure also helps there.
It also adds `assert_ignored` which is used before a `TyCtxt` is created. Instead of adding a new ignore task this simply ensures that we are in a context where reads are ignored.
r? @michaelwoerister
When gluing two tokens, the second of which is joint, the result should also be
joint.
This fixes an issue with joining three `Dot` tokens to make a `DotDotDot` - the
intermediate `DotDot` would not be joint and therefore we would not attempt to
glue the last `Dot` token, yielding `.. .` instead of `...`.
[incremental] Specialize encoding and decoding of Fingerprints
This saves the storage space used by about 32 bits per `Fingerprint`.
On average, this reduces the size of the `/target/{mode}/incremental`
folder by roughly 5% [Full details here](https://gist.github.com/wesleywiser/264076314794fbd6a4c110d7c1adc43e).
Fixes#45875
r? @michaelwoerister
Fix built-in indexing not being used where index type wasn't "obviously" usize
Fixes#33903Fixes#46095
This PR was made possible thanks to the generous help of @eddyb
Following the example of binary operators, builtin checking for indexing has been moved from the typecheck stage to a writeback stage, after type constraints have been resolved.
Deprecate [T]::rotate in favor of [T]::rotate_{left,right}.
Background
==========
Slices currently have an **unstable** [`rotate`] method which rotates
elements in the slice to the _left_ N positions. [Here][tracking] is the
tracking issue for this unstable feature.
```rust
let mut a = ['a', 'b' ,'c', 'd', 'e', 'f'];
a.rotate(2);
assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);
```
Proposal
========
Deprecate the [`rotate`] method and introduce `rotate_left` and
`rotate_right` methods.
```rust
let mut a = ['a', 'b' ,'c', 'd', 'e', 'f'];
a.rotate_left(2);
assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);
```
```rust
let mut a = ['a', 'b' ,'c', 'd', 'e', 'f'];
a.rotate_right(2);
assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);
```
Justification
=============
I used this method today for my first time and (probably because I’m a
naive westerner who reads LTR) was surprised when the docs mentioned that
elements get rotated in a left-ward direction. I was in a situation
where I needed to shift elements in a right-ward direction and had to
context switch from the main problem I was working on and think how much
to rotate left in order to accomplish the right-ward rotation I needed.
Ruby’s `Array.rotate` shifts left-ward, Python’s `deque.rotate` shifts
right-ward. Both of their implementations allow passing negative numbers
to shift in the opposite direction respectively. The current `rotate`
implementation takes an unsigned integer argument which doesn't allow
the negative number behavior.
Introducing `rotate_left` and `rotate_right` would:
- remove ambiguity about direction (alleviating need to read docs 😉)
- make it easier for people who need to rotate right
[`rotate`]: https://doc.rust-lang.org/std/primitive.slice.html#method.rotate
[tracking]: https://github.com/rust-lang/rust/issues/41891
This saves the storage space used by about 32 bits per `Fingerprint`.
On average, this reduces the size of the `/target/{mode}/incremental`
folder by roughly 5%.
Fixes#45875
