In which we start to parse const generics defaults
As discussed in this [zulip topic](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/const.20generic.20defaults), this PR extracts the parsing parts from `@JulianKnodt's` PR #75384 for a better user-experience using the newly stabilized `min_const_generics` (albeit temporary) as shown in #80507: trying to use default values on const generics currently results in parse errors, as if the user didn't use the correct syntax (which is somewhat true but also misleading).
This PR extracts (and slightly modifies in a couple places) `@JulianKnodt's` parsing code (with attribution if I've done everything correctly), AST and HIR changes, and feature gate setup.
This feature is now marked as "incomplete" and thus will also print out the expected "const generics default values are unstable" error instead of a syntax error. Note that, as I've only extracted the parsing part, the actual feature will not work at all if enabled. There will be ICEs, and inference errors on the const generics default values themselves.
Fixes#80507.
Once this merges, I'll:
- modify the const generics tracking issue to refer to the `const_generics_defaults` gate rather than the older temporary name it uses there.
- create the GH `F-const_generics_defaults` label
r? `@varkor`
- Adds optional default values to const generic parameters in the AST
and HIR
- Parses these optional default values
- Adds a `const_generics_defaults` feature gate
Add edition 2021.
🎆 Happy new ~~year~~ Rust. 🍾
This adds --edition=2021, and updates suggestions about 2018 to say "2018 *or later*".
Related Cargo PR: https://github.com/rust-lang/cargo/pull/8922
---
Edit: This adds the new edition as *unstable*. Without `-Z unstable-options`, `--edition=2021` results in:
```
$ rustc --edition=2021
error: edition 2021 is unstable and only available with -Z unstable-options.
```
Update LLVM
- [GlobalISel][IRTranslator] Fix a crash when the use of an extractvalue is a non-dominated metadata use.
- [asan] Use dynamic shadow memory position on Apple Silicon macOS
r? ``@cuviper``
Fix broken ./x.py install
During my tarball refactorings in https://github.com/rust-lang/rust/pull/79788 I changed the directory layout used by the tarball generation code, and that broke the other parts of rustbuild which hardcoded the paths of those directories. Namely, `./x.py install` relied on the uncompressed copy of the tarball left behind by `fabricate`/`rust-installer`, causing https://github.com/rust-lang/rust/issues/80494.
While the easy fix for https://github.com/rust-lang/rust/issues/80494 would've been to just update the hardcoded paths to match the new structure, that fix would leave us in the same situation if we were to change the directory layout again in the future. Instead I refactored the code to return a `GeneratedTarball` struct as the output of all the dist steps, and I put all the paths the rest of rustbuild needs to care about in its fields. That way, future changes to `src/bootstrap/tarball.rs` will not break other stuff.
This PR is best reviewed commit-by-commit.
r? `@Mark-Simulacrum`
`@rustbot` modify labels: beta-nominated beta-accepted T-release
Update and improve `rustc_codegen_{llvm,ssa}` docs
Fixes#75342.
These docs were very out of date and misleading. They even said that
they codegen'd the *AST*!
For some reason, the `rustc_codegen_ssa::base` docs were exactly
identical to the `rustc_codegen_llvm::base` docs. They didn't really
make sense, because they had LLVM-specific information even though
`rustc_codegen_ssa` is supposed to be somewhat generic. So I removed
them as they were misleading.
r? ``@pnkfelix`` maybe?
The return of the GroupBy and GroupByMut iterators on slice
According to https://github.com/rust-lang/rfcs/pull/2477#issuecomment-742034372, I am opening this PR again, this time I implemented it in safe Rust only, it is therefore much easier to read and is completely safe.
This PR proposes to add two new methods to the slice, the `group_by` and `group_by_mut`. These two methods provide a way to iterate over non-overlapping sub-slices of a base slice that are separated by the predicate given by the user (e.g. `Partial::eq`, `|a, b| a.abs() < b.abs()`).
```rust
let slice = &[1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.group_by(|a, b| a == b);
assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
assert_eq!(iter.next(), Some(&[3, 3][..]));
assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
assert_eq!(iter.next(), None);
```
[An RFC](https://github.com/rust-lang/rfcs/pull/2477) was open 2 years ago but wasn't necessary.
