tree-wide: parallel: Fully removed all `Lrc`, replaced with `Arc`
tree-wide: parallel: Fully removed all `Lrc`, replaced with `Arc`
This is continuation of https://github.com/rust-lang/rust/pull/132282 .
I'm pretty sure I did everything right. In particular, I searched all occurrences of `Lrc` in submodules and made sure that they don't need replacement.
There are other possibilities, through.
We can define `enum Lrc<T> { Rc(Rc<T>), Arc(Arc<T>) }`. Or we can make `Lrc` a union and on every clone we can read from special thread-local variable. Or we can add a generic parameter to `Lrc` and, yes, this parameter will be everywhere across all codebase.
So, if you think we should take some alternative approach, then don't merge this PR. But if it is decided to stick with `Arc`, then, please, merge.
cc "Parallel Rustc Front-end" ( https://github.com/rust-lang/rust/issues/113349 )
r? SparrowLii
`@rustbot` label WG-compiler-parallel
Document minimum supported host tooling on macOS
In particular we support macOS 10.12 (same as for binaries produced by `rustc`) and Xcode 9.2 (the highest Xcode version that runs on macOS 10.12.6). I have this installed on a MacBook Pro from 2013 that sits below my desk, and am occasionally testing it.
I am documenting this now because it was unclear in https://github.com/rust-lang/rust/issues/136523.
(I'm not inherently against bumping these one day, but that's a separate discussion, let's at least document what we support right now).
`@rustbot` label O-macos
Implement unstable `new_range` feature
Switches `a..b`, `a..`, and `a..=b` to resolve to the new range types.
For rust-lang/rfcs#3550
Tracking issue #123741
also adds the re-export that was missed in the original implementation of `new_range_api`
Update books
## rust-lang/book
2 commits in fa312a343fbff01bc6cef393e326817f70719813..e2fa4316c5a7c0d2499c5d6b799adcfad6ef7a45
2025-02-03 15:02:07 UTC to 2025-02-01 17:33:39 UTC
- Add missing word in ch17-04-streams.md (rust-lang/book#4218)
- Fix typo in ch5.3 and in CONTRIBUTING.md (rust-lang/book#4216)
## rust-lang/edition-guide
2 commits in 4ed5a1a4a2a7ecc2e529a5baaef04f7bc7917eda..f56aecc3b036dff16404b525a83b00f911b9bbea
2025-02-03 17:14:16 UTC to 2025-01-31 17:44:00 UTC
- Rustc{En,De}codable has been removed (rust-lang/edition-guide#353)
- Remove rustfmt-overflow-delimited-expr (rust-lang/edition-guide#357)
## rust-lang/nomicon
3 commits in bc2298865544695c63454fc1f9f98a3dc22e9948..336f75835a6c0514852cc65aba9a698b699b13c8
2025-02-02 10:06:30 UTC to 2025-02-02 08:35:20 UTC
- Improve grammar in exotic-sizes (rust-lang/nomicon#452)
- other-reprs: Add details for n!=1 repr(packed) (rust-lang/nomicon#460)
- Use `()` instead of `[u8; 0]` in opaque type (rust-lang/nomicon#456)
## rust-lang/reference
3 commits in 93b921c7d3213d38d920f7f905a3bec093d2217d..4249fb411dd27f945e2881eb0378044b94cee06f
2025-01-31 03:43:07 UTC to 2025-01-29 04:17:34 UTC
- Add Spec Identifier Syntax to expressions.md and subchapters (rust-lang/reference#1591)
- Exclude the test summary from the search index (rust-lang/reference#1723)
- Spec inline assembly tests (rust-lang/reference#1648)
## rust-lang/rust-by-example
1 commits in 054259ed1bf01cdee4309ee764c7e103f6df3de5..743766929f1e53e72fab74394ae259bbfb4a7619
2025-02-02 19:53:31 UTC to 2025-02-02 19:53:31 UTC
- Spanish translation to 1:2100 (rust-lang/rust-by-example#1910)
Improve documentation when adding a new target
https://github.com/rust-lang/rust/pull/133631#issuecomment-2607877936 shows that it can be a bit difficult process-wise to add a new target.
I've added a bit of text to the docs, suggesting that users add the target defintion/spec first, and later work on `std` support.
I also found that we have two places where we document how to add a new target. I've linked these for now, but they should probably be merged somehow in the future.
`@rustbot` label A-docs
r? compiler
CC `@workingjubilee` who's worked a lot on target specs IIRC.
[rustdoc] Add `--extract-doctests` command-line flag
Part of https://github.com/rust-lang/rust/issues/134529.
It was discussed with the Rust-for-Linux project recently that they needed a way to extract doctests so they can modify them and then run them more easily (look for "a way to extract doctests" [here](https://github.com/Rust-for-Linux/linux/issues/2)).
For now, I output most of `ScrapedDoctest` fields in JSON format with `serde_json`. So it outputs the following information:
* filename
* line
* langstr
* text
cc `@ojeda`
r? `@notriddle`
Disable `overflow_delimited_expr` in edition 2024
This reverts the style guide changes and sets the default to "false" in rustfmt for style edition 2024.
r? `@ytmimi`
cc `@rust-lang/style` `@rust-lang/rustfmt`
Autodiff Upstreaming - rustc_codegen_ssa, rustc_middle
This PR should not be merged until the rustc_codegen_llvm part is merged.
I will also alter it a little based on what get's shaved off from the cg_llvm PR,
and address some of the feedback I received in the other PR (including cleanups).
I am putting it already up to
1) Discuss with `@jieyouxu` if there is more work needed to add tests to this and
2) Pray that there is someone reviewing who can tell me why some of my autodiff invocations get lost.
Re 1: My test require fat-lto. I also modify the compilation pipeline. So if there are any other llvm-ir tests in the same compilation unit then I will likely break them. Luckily there are two groups who currently have the same fat-lto requirement for their GPU code which I have for my autodiff code and both groups have some plans to enable support for thin-lto. Once either that work pans out, I'll copy it over for this feature. I will also work on not changing the optimization pipeline for functions not differentiated, but that will require some thoughts and engineering, so I think it would be good to be able to run the autodiff tests isolated from the rest for now. Can you guide me here please?
For context, here are some of my tests in the samples folder: https://github.com/EnzymeAD/rustbook
Re 2: This is a pretty serious issue, since it effectively prevents publishing libraries making use of autodiff: https://github.com/EnzymeAD/rust/issues/173. For some reason my dummy code persists till the end, so the code which calls autodiff, deletes the dummy, and inserts the code to compute the derivative never gets executed. To me it looks like the rustc_autodiff attribute just get's dropped, but I don't know WHY? Any help would be super appreciated, as rustc queries look a bit voodoo to me.
Tracking:
- https://github.com/rust-lang/rust/issues/124509
r? `@jieyouxu`
Fix deduplication mismatches in vtables leading to upcasting unsoundness
We currently have two cases where subtleties in supertraits can trigger disagreements in the vtable layout, e.g. leading to a different vtable layout being accessed at a callsite compared to what was prepared during unsizing. Namely:
### #135315
In this example, we were not normalizing supertraits when preparing vtables. In the example,
```
trait Supertrait<T> {
fn _print_numbers(&self, mem: &[usize; 100]) {
println!("{mem:?}");
}
}
impl<T> Supertrait<T> for () {}
trait Identity {
type Selff;
}
impl<Selff> Identity for Selff {
type Selff = Selff;
}
trait Middle<T>: Supertrait<()> + Supertrait<T> {
fn say_hello(&self, _: &usize) {
println!("Hello!");
}
}
impl<T> Middle<T> for () {}
trait Trait: Middle<<() as Identity>::Selff> {}
impl Trait for () {}
fn main() {
(&() as &dyn Trait as &dyn Middle<()>).say_hello(&0);
}
```
When we prepare `dyn Trait`, we see a supertrait of `Middle<<() as Identity>::Selff>`, which itself has two supertraits `Supertrait<()>` and `Supertrait<<() as Identity>::Selff>`. These two supertraits are identical, but they are not duplicated because we were using structural equality and *not* considering normalization. This leads to a vtable layout with two trait pointers.
When we upcast to `dyn Middle<()>`, those two supertraits are now the same, leading to a vtable layout with only one trait pointer. This leads to an offset error, and we call the wrong method.
### #135316
This one is a bit more interesting, and is the bulk of the changes in this PR. It's a bit similar, except it uses binder equality instead of normalization to make the compiler get confused about two vtable layouts. In the example,
```
trait Supertrait<T> {
fn _print_numbers(&self, mem: &[usize; 100]) {
println!("{mem:?}");
}
}
impl<T> Supertrait<T> for () {}
trait Trait<T, U>: Supertrait<T> + Supertrait<U> {
fn say_hello(&self, _: &usize) {
println!("Hello!");
}
}
impl<T, U> Trait<T, U> for () {}
fn main() {
(&() as &'static dyn for<'a> Trait<&'static (), &'a ()>
as &'static dyn Trait<&'static (), &'static ()>)
.say_hello(&0);
}
```
When we prepare the vtable for `dyn for<'a> Trait<&'static (), &'a ()>`, we currently consider the PolyTraitRef of the vtable as the key for a supertrait. This leads two two supertraits -- `Supertrait<&'static ()>` and `for<'a> Supertrait<&'a ()>`.
However, we can upcast[^up] without offsetting the vtable from `dyn for<'a> Trait<&'static (), &'a ()>` to `dyn Trait<&'static (), &'static ()>`. This is just instantiating the principal trait ref for a specific `'a = 'static`. However, when considering those supertraits, we now have only one distinct supertrait -- `Supertrait<&'static ()>` (which is deduplicated since there are two supertraits with the same substitutions). This leads to similar offsetting issues, leading to the wrong method being called.
[^up]: I say upcast but this is a cast that is allowed on stable, since it's not changing the vtable at all, just instantiating the binder of the principal trait ref for some lifetime.
The solution here is to recognize that a vtable isn't really meaningfully higher ranked, and to just treat a vtable as corresponding to a `TraitRef` so we can do this deduplication more faithfully. That is to say, the vtable for `dyn for<'a> Tr<'a>` and `dyn Tr<'x>` are always identical, since they both would correspond to a set of free regions on an impl... Do note that `Tr<for<'a> fn(&'a ())>` and `Tr<fn(&'static ())>` are still distinct.
----
There's a bit more that can be cleaned up. In codegen, we can stop using `PolyExistentialTraitRef` basically everywhere. We can also fix SMIR to stop storing `PolyExistentialTraitRef` in its vtable allocations.
As for testing, it's difficult to actually turn this into something that can be tested with `rustc_dump_vtable`, since having multiple supertraits that are identical is a recipe for ambiguity errors. Maybe someone else is more creative with getting that attr to work, since the tests I added being run-pass tests is a bit unsatisfying. Miri also doesn't help here, since it doesn't really generate vtables that are offset by an index in the same way as codegen.
r? `@lcnr` for the vibe check? Or reassign, idk. Maybe let's talk about whether this makes sense.
<sup>(I guess an alternative would also be to not do any deduplication of vtable supertraits (or only a really conservative subset) rather than trying to normalize and deduplicate more faithfully here. Not sure if that works and is sufficient tho.)</sup>
cc `@steffahn` -- ty for the minimizations
cc `@WaffleLapkin` -- since you're overseeing the feature stabilization :3
Fixes#135315Fixes#135316
