Rollup of 8 pull requests
Successful merges:
- #97506 (Stabilize `nonnull_slice_from_raw_parts`)
- #98651 (Follow C-RW-VALUE in std::io::Cursor example)
- #102742 (Remove unnecessary raw pointer in __rust_start_panic arg)
- #109587 (Use an IndexVec to debug fingerprints.)
- #109613 (fix type suggestions in match arms)
- #109633 (Fix "Directly go to item in search if there is only one result" setting)
- #109635 (debuginfo: Get pointer size/align from tcx.data_layout instead of layout_of)
- #109641 (Don't elaborate non-obligations into obligations)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Don't elaborate non-obligations into obligations
It's suspicious to elaborate a `PolyTraitRef` or `Predicate` into an `Obligation`, since the former does not have a param-env associated with it, but the latter does. This is a footgun that, while not being misused *currently* in the compiler, easily could be misused by someone less familiar with the elaborator's inner workings.
This PR just changes the API -- ideally, the elaborator wouldn't even have to deal with obligations if we're not elaborating obligations, but that would require a bit more abstraction than I could be bothered with today.
debuginfo: Get pointer size/align from tcx.data_layout instead of layout_of
This avoids some type interning and a query execution. It also just makes the code simpler.
Cleanup `codegen_fn_attrs`
The `match` control flow construct has been stable since 1.0, we should use it here.
Sorry for the hard to review diff, I did try to at least split it into two commits. But looking at before-after side-by-side (instead of whatever github is doing) is probably the easiest way to make sure that I didn't forget about anything.
On top of #109088, you can wait for that
Refactor: `VariantIdx::from_u32(0)` -> `FIRST_VARIANT`
Since structs are always `VariantIdx(0)`, there's a bunch of files where the only reason they had `VariantIdx` or `vec::Idx` imported at all was to get the first variant.
So this uses a constant for that, and adds some doc-comments to `VariantIdx` while I'm there, since [it doesn't have any today](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_target/abi/struct.VariantIdx.html).
Still-further-specializable projections are ambiguous in new solver
Fixes https://github.com/rust-lang/rust/pull/108896/files#r1148450781
r? ``@BoxyUwU`` (though feel free to re-roll)
---
This can be used to create an unsound transmute function with the new solver:
```rust
#![feature(specialization)]
trait Default {
type Id;
fn intu(&self) -> &Self::Id;
}
impl<T> Default for T {
default type Id = T;
fn intu(&self) -> &Self::Id {
self
}
}
fn transmute<T: Default<Id = U>, U: Copy>(t: T) -> U {
*t.intu()
}
use std::num::NonZeroU8;
fn main() {
let s = transmute::<u8, Option<NonZeroU8>>(0);
assert_eq!(s, None);
}
```
Permit the MIR inliner to inline diverging functions
This heuristic prevents inlining of `hint::unreachable_unchecked`, which in turn makes `Option/Result::unwrap_unchecked` a bad inlining candidate. I looked through the changes to `core`, `alloc`, `std`, and `hashbrown` by hand and they all seem reasonable. Let's see how this looks in perf...
---
Based on rustc-perf it looks like this regresses ctfe-stress, and the cachegrind diff indicates that this regression is in `InterpCx::statement`. I don't know how to do any deeper analysis because that function is _enormous_ in the try toolchain, which has no debuginfo in it. And a local build produces significantly different codegen for that function, even with LTO.
Since structs are always `VariantIdx(0)`, there's a bunch of files where the only reason they had `VariantIdx` or `vec::Idx` imported at all was to get the first variant.
So this uses a constant for that, and adds some doc-comments to `VariantIdx` while I'm there, since it doesn't have any today.
Refactor `try_execute_query`
This merges `JobOwner::try_start` into `try_execute_query`, removing `TryGetJob` in the processes. 3 new functions are extracted from `try_execute_query`: `execute_job`, `cycle_error` and `wait_for_query`. This makes the control flow a bit clearer and improves performance.
Based on https://github.com/rust-lang/rust/pull/109046.
<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check</td><td align="right">1.7134s</td><td align="right">1.7061s</td><td align="right"> -0.43%</td></tr><tr><td>🟣 <b>hyper</b>:check</td><td align="right">0.2519s</td><td align="right">0.2510s</td><td align="right"> -0.35%</td></tr><tr><td>🟣 <b>regex</b>:check</td><td align="right">0.9517s</td><td align="right">0.9481s</td><td align="right"> -0.38%</td></tr><tr><td>🟣 <b>syn</b>:check</td><td align="right">1.5389s</td><td align="right">1.5338s</td><td align="right"> -0.33%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check</td><td align="right">5.9488s</td><td align="right">5.9258s</td><td align="right"> -0.39%</td></tr><tr><td>Total</td><td align="right">10.4048s</td><td align="right">10.3647s</td><td align="right"> -0.38%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">0.9962s</td><td align="right"> -0.38%</td></tr></table>
r? `@cjgillot`
