Support tail calls in mir via `TerminatorKind::TailCall`
This is one of the interesting bits in tail call implementation — MIR support.
This adds a new `TerminatorKind` which represents a tail call:
```rust
TailCall {
func: Operand<'tcx>,
args: Vec<Operand<'tcx>>,
fn_span: Span,
},
```
*Structurally* this is very similar to a normal `Call` but is missing a few fields:
- `destination` — tail calls don't write to destination, instead they pass caller's destination to the callee (such that eventual `return` will write to the caller of the function that used tail call)
- `target` — similarly to `destination` tail calls pass the caller's return address to the callee, so there is nothing to do
- `unwind` — I _think_ this is applicable too, although it's a bit confusing
- `call_source` — `become` forbids operators and is not created as a lowering of something else; tail calls always come from HIR (at least for now)
It might be helpful to read the interpreter implementation to understand what `TailCall` means exactly, although I've tried documenting it too.
-----
There are a few `FIXME`-questions still left, ideally we'd be able to answer them during review ':)
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r? `@oli-obk`
cc `@scottmcm` `@DrMeepster` `@JakobDegen`
Cache hir_owner_nodes in ParentHirIterator.
Lint level computation may traverse deep HIR trees using that iterator. This calls `hir_owner_nodes` many times for the same HIR owner, which is wasterful.
This PR caches the value to allow a more efficient iteration scheme.
r? ghost for perf
Make `can_eq` process obligations (almost) everywhere
Move `can_eq` to an extension trait on `InferCtxt` in `rustc_trait_selection`, and change it so that it processes obligations. This should strengthen it to be more accurate in some cases, but is most important for the new trait solver which delays relating aliases to `AliasRelate` goals. Without this, we always basically just return true when passing aliases to `can_eq`, which can lead to weird errors, for example #127149.
I'm not actually certain if we should *have* `can_eq` be called on the good path. In cases where we need `can_eq`, we probably should just be using a regular probe.
Fixes#127149
r? lcnr
Update cargo
20 commits in a515d463427b3912ec0365d106791f88c1c14e1b..154fdac39ae9629954e19e9986fd2cf2cdd8d964
2024-07-02 20:53:36 +0000 to 2024-07-07 01:28:23 +0000
- test: relax redactions for rust-lang/rust (rust-lang/cargo#14203)
- use "bootstrap" instead of "rustbuild" (rust-lang/cargo#14207)
- test: migrate serveral files to snapbox (rust-lang/cargo#14180)
- Add rustdocflags to Unit's Debug impl (rust-lang/cargo#14201)
- Allow enabling `config-include` feature in config (rust-lang/cargo#14196)
- fix(test): Restore `does_not_contain` for check (rust-lang/cargo#14198)
- test: migrate patch, pkgid, proc_macro and progress to snapbox (rust-lang/cargo#14181)
- test: Migrate jobserver to snapbox (rust-lang/cargo#14191)
- chore(deps): update msrv (3 versions) to v1.77 (rust-lang/cargo#14186)
- test: migrate build_plan and build_script to snapbox (rust-lang/cargo#14193)
- test: migrate cfg and check to snapbox (rust-lang/cargo#14185)
- test: migrate install* and inheritable_workspace_fields to snapbox (rust-lang/cargo#14170)
- Pass rustflags to artifacts built with implicit targets when using target-applies-to-host (rust-lang/cargo#13900)
- test: Migrate network tests to snapbox (rust-lang/cargo#14187)
- test: migrate some files to snapbox (rust-lang/cargo#14113)
- test: Auto-redact `... after last build at ...`; Migrate `freshness` to Snapbox (rust-lang/cargo#14161)
- chore: fix some typos (rust-lang/cargo#14182)
- fix: improve message for inactive weak optional feature with edition2024 through unused dep collection (rust-lang/cargo#14026)
- test：migrate `doc/directory/docscrape` to snapbox (rust-lang/cargo#14171)
- test: Migrate git_auth to snapbox (rust-lang/cargo#14172)
Rollup of 8 pull requests
Successful merges:
- #127179 (Print `TypeId` as hex for debugging)
- #127189 (LinkedList's Cursor: method to get a ref to the cursor's list)
- #127236 (doc: update config file path in platform-support/wasm32-wasip1-threads.md)
- #127297 (Improve std::Path's Hash quality by avoiding prefix collisions)
- #127308 (Attribute cleanups)
- #127354 (Describe Sized requirements for mem::offset_of)
- #127409 (Emit a wrap expr span_bug only if context is not tainted)
- #127447 (once_lock: make test not take as long in Miri)
r? `@ghost`
`@rustbot` modify labels: rollup
Make tidy problematic const checking fast again
fixes pathological tidy performance described in #127453 by reverting #127428
i think anyone can approve this ASAP, it makes working on this repo significantly worse.
once_lock: make test not take as long in Miri
Allocating 1000 list elements takes a while (`@zachs18` reported >5min), so let's reduce the iteration count when running in Miri. Unfortunately due to this clever `while let i @ 0..LEN =` thing, the count needs to be a constants, and constants cannot be shadowed, so we need to use another trick to hide the `cfg!(miri)` from the docs. (I think this loop condition may be a bit too clever, it took me a bit to decipher. Ideally this would be `while let i = ... && i < LEN`, but that is not stable yet.)
Describe Sized requirements for mem::offset_of
The container doesn't have to be sized, but the field must be sized (at least until https://github.com/rust-lang/rust/issues/126151 is stable).
Improve std::Path's Hash quality by avoiding prefix collisions
This adds a bit rotation to the already existing state so that the same sequence of characters chunked at different offsets into separate path components results in different hashes.
The tests are from #127255Closes#127254
LinkedList's Cursor: method to get a ref to the cursor's list
We're already providing `.back()` & `.front()`, for which we hold onto a reference to the parent list, so why not share it? Useful for when you got `LinkedList` -> `CursorMut` -> `Cursor` and cannot take another ref to the list, even though you should be able to. This seems to be completely safe & sound.
The name is, of course, bikesheddable.
Print `TypeId` as hex for debugging
In <https://github.com/rust-lang/rust/pull/127134>, the `Debug` impl for `TypeId` was changed to print a single integer rather than a tuple. Change this again to print as hex for more concise and consistent formatting, as was suggested.
Result:
TypeId(0x1378bb1c0a0202683eb65e7c11f2e4d7)
Specialize `TrustedLen` for `Iterator::unzip()`
Don't check the capacity every time (and also for `Extend` for tuples, as this is how `unzip()` is implemented).
I did this with an unsafe method on `Extend` that doesn't check for growth (`extend_one_unchecked()`). I've marked it as perma-unstable currently, although we may want to expose it in the future so collections outside of std can benefit from it. Then specialize `Extend for (A, B)` for `TrustedLen` to call it.
An alternative way of implementing this is to have a semi-public trait (`#[doc(hidden)]` public, so collections outside of core can implement it) for `extend()` inside tuples, and specialize it from collections. However:
1. This looks more complex to me.
2. This prohibits the option of exposing this somewhen to collections outside of std, as we never expose specializations.
A concern that may arise with the current approach is that implementing `extend_one_unchecked()` correctly must also incur implementing `extend_reserve()`, otherwise you can have UB. This is a somewhat non-local safety invariant. However, I believe this is fine, since to have actual UB you must have unsafe code inside your `extend_one_unchecked()` that makes incorrect assumption, *and* not implement `extend_reserve()`. I've also documented this requirement.
**Benchmark:**
Code:
```rust
#[bench]
fn unzip(b: &mut Bencher) {
b.iter(|| {
for _ in 0..10_000 {
let v: (Vec<_>, VecDeque<_>) =
(black_box(0u32)..black_box(1_000)).map(|i| (i, i * 2)).unzip();
black_box(v);
}
});
}
```
Before:
```
unzip::unzip 14.17ms/iter +/- 374.85µs
```
After:
```
unzip::unzip 5.33ms/iter +/- 164.54µs
```
