Contract variables can be declared in the `requires` clause and
can be referenced both in `requires` and `ensures`, subject to usual
borrow checking rules.
This allows any setup common to both the `requires` and `ensures`
clauses to only be done once.
`is_ascii` on an empty string or slice returns true
Update the description of the [`is_ascii`](https://doc.rust-lang.org/std/primitive.str.html#method.is_ascii) functions - an empty string or slice also returns `true`.
This follows the pattern of [`all()`](https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.all). Clippy currently suggests to change `string.chars().all(|c| c.is_ascii())` into `string.is_ascii()`. This suggestion therefore seems fitting.
I've already questioned the behavior for this multiple times. I've always had to check the internals to conclude how it works. That's why I'm opening this PR to add it directly in the documentation.
style-guide: fix typo for empty struct advice
the advice appears to apply to empty structs with braces (parens/blocks), and a unit struct in the comment does not make sense. Fix the typo.
Use `bit_set::Word` in a couple more places.
It's a synonym for `u64` and there are a couple of places where we use `u64` where we should use `Word`, which this commit fixes.
I found this when I tried changing `Word` to `u128` (which made performance worse).
r? `````@Zalathar`````
Fix ICE on offsetted ZST pointer
I'm not sure this is the *right* fix, but it's simple enough and does roughly what I'd expect. Like with the previous optimization to codegen usize rather than a zero-sized static, there's no guarantee that we continue returning a particular value from the offsetting.
A grep for `const_usize.*align` found the same code copied to rustc_codegen_gcc and cranelift but a quick skim didn't find other cases of similar 'optimization'. That said, I'm not convinced I caught everything, it's not trivial to search for this.
Closesrust-lang/rust#147516
std: Add Motor OS std library port
Motor OS was added as a no-std Tier-3 target in
[PR 146848](https://github.com/rust-lang/rust/pull/146848) as x86_64-unknown-motor.
This PR adds the std library for Motor OS.
While the PR may seem large, all it does is proxy
std pal calls to [moto-rt](https://crates.io/crates/moto-rt). Where there is some non-trivial
code (e.g. thread::spawn), it is quite similar, often
identical, to what other platforms do.
Guard HIR lowered contracts with `contract_checks`
Refactor contract HIR lowering to ensure no contract code is executed when contract-checks are disabled.
The call to `contract_checks` is moved to inside the lowered fn body, and contract closures are built conditionally, ensuring no side-effects present in contracts occur when those are disabled. This partially addresses rust-lang/rust#139548, i.e. the bad behavior no longer happens with contract checks disabled (`-Zcontract-checks=no`).
The change is made in preparation for adding contract variable declarations - variables declared before the `requires` assertion, and accessible from both `requires` and `ensures`, but not in the function body (PR rust-lang/rust#144444). As those declarations may also have side-effects, it's good to guard them with `contract_checks` - the new lowering approach allows for this to be done easily.
Contracts tracking issue: rust-lang/rust#128044
**Known limiatations**:
- It is still possible to early return from the *function* from within a contract, e.g.
```rust
#[ensures({if x > 0 { return 0 }; |_| true})]
fn foo(x: u32) -> i32 {
42
}
```
When `foo` is called with an argument greater than 0, instead of `42`, `0` will be returned.
As this is not a regression, it is not addressed in this PR. However, it may be worth revisiting later down the line, as users may expect a form of early return from *contract specifications*, and so returning from the entire *function* could cause confusion.
- ~Contracts are still not optimised out when disabled. Currently, even when contracts are disabled, the code generated causes existing optimisations to fail, meaning even disabled contracts could impact runtime performance. This issue is blocking rust-lang/rust#136578, and has not been addressed in this PR, i.e. the `mir-opt` and `codegen` tests that fail in rust-lang/rust#136578 still fail with these new HIR lowering changes.~ Contracts should now be optimised out when disabled, however some regressions tests still need to be added to be sure that is indeed the case.
It's a synonym for `u64` and there are a couple of places where we use
`u64` where we should use `Word`, which this commit fixes.
I found this when I tried changing `Word` to `u128` (which made
performance worse).
Rollup of 11 pull requests
Successful merges:
- rust-lang/rust#143191 (Stabilize `rwlock_downgrade` library feature)
- rust-lang/rust#147444 (Allow printing a fully-qualified path in `def_path_str`)
- rust-lang/rust#147527 (Update t-compiler beta nomination Zulip msg)
- rust-lang/rust#147670 (some `ErrorGuaranteed` cleanups)
- rust-lang/rust#147676 (Return spans out of `is_doc_comment` to reduce reliance on `.span()` on attributes)
- rust-lang/rust#147708 (const `mem::drop`)
- rust-lang/rust#147710 (Fix ICE when using contracts on async functions)
- rust-lang/rust#147716 (Fix some comments)
- rust-lang/rust#147718 (miri: use allocator_shim_contents codegen helper)
- rust-lang/rust#147729 (ignore boring locals when explaining why a borrow contains a point due to drop of a live local under polonius)
- rust-lang/rust#147742 (Revert unintentional whitespace changes to rustfmt-excluded file)
r? `@ghost`
`@rustbot` modify labels: rollup
ignore boring locals when explaining why a borrow contains a point due to drop of a live local under polonius
Polonius liveness has to contain boring locals, and we ignore them in diagnostics, to match NLL diagnostics that never involve any boring locals. When explaining why a borrow contains a point, I ignored these boring locals when it was due to a use of a live var, but forgot to do so when the cause was because of a drop of a live var.
This is what was causing the last two (known) diagnostics differences under the polonius compare-mode:
- `tests/ui/dropck/dropck_trait_cycle_checked.rs`
- `tests/ui/unboxed-closures/unboxed-closures-failed-recursive-fn-1.rs`
r? `@jackh726`
Fix ICE when using contracts on async functions
Fixesrust-lang/rust#145333
contract is not supported for async functions right now, it's not properly lowered and getting HirId will ICE.
This PR adds checking for async function in expanding AST phase, it's better until we want to fully support async for contracts feature.
const `mem::drop`
I'm putting this under the `const Destruct` feature flag since it doesn't really feel relevant to put it elsewhere… it's just an empty function body, so, it doesn't have any particular weirdness attached to it (unlike `drop_in_place`, for example).
r? wg-const-eval
Update t-compiler beta nomination Zulip msg
Sister patch of [triagebot#2191](https://github.com/rust-lang/triagebot/pull/2191)
Follow-up to rust-lang/rust#147263
The triagebot now triggers a different message when a PR is nominated for backport, making it look like more a suggestion to evaluate for the author/reviewers than a mandatory decision for the team to take.
The wording (as per [triagebot#2191](https://github.com/rust-lang/triagebot/pull/2191)) is open to suggestions.
Thanks
Allow printing a fully-qualified path in `def_path_str`
Previously, the local crate would always be printed as a leading `crate::`. Allow resolving it to the crate name instead.
This allows printing a fully qualified path with:
```rust
let qualified_name = with_no_visible_paths!(with_resolve_crate_name!(
with_no_trimmed_paths!(tcx.def_path_str(def_id))
));
```
I found this useful for an out-of-tree rustc-driver. I do not currently have a usecase in mind upstream; I'm ok if you don't want this PR for that reason. See [#t-compiler/help > print a fully qualified path name? @ 💬](https://rust-lang.zulipchat.com/#narrow/channel/182449-t-compiler.2Fhelp/topic/print.20a.20fully.20qualified.20path.20name.3F/near/541560961) for additional context.
This does not currently have tests. I am not aware of an easy way to test def-id printing, since it requires having access to a TyCtxt.
Stabilize `rwlock_downgrade` library feature
Tracking Issue: https://github.com/rust-lang/rust/issues/128203
Method to be stabilized:
```rust
impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
pub fn downgrade(s: Self) -> RwLockReadGuard<'a, T> {}
}
```
~~I would like to point out that my documentation comment is longer than ideal, but at the same time I don't really know how else to show why `downgrade` is actually necessary (instead of just unlocking and relocking). If anyone has ideas for making this more concise that would be great!~~ I have made the documentation a bit more clear.
Stabilization report: https://github.com/rust-lang/rust/issues/128203#issuecomment-3016682463
- only lint on definitions of offending mutexes, not all their uses
(fixes https://github.com/rust-lang/rust-clippy/issues/13378)
- give more orderly help messages
- stop linting on `Mutex<*const T>` (see the corresponding commit for
context)
- offer (partial) suggestions
The last change might be deemed a bit too much for the feature freeze,
but it can be easily extracted out into a separate PR.
changelog: [`mutex_atomic`]: only lint the definitions, not uses
changelog: [`mutex_atomic`]: better help messages, and suggestions
changelog: [`mutex_atomic`]: don't lint `Mutex<*const T>`
changelog: [`mutex_integer`]: only lint the definitions, not uses
changelog: [`mutex_integer`]: better help messages, and suggestions
prefer alias candidates for sizedness + auto trait goals
Fixesrust-lang/rust#143992
- abd07dec44437554520453f929c2b12d4eb8b11e: Reverts rust-lang/rust#144016 so that `MetaSized` bounds are checked properly, and updates all the tests accordingly, including making `tests/ui/sized-hierarchy/incomplete-inference-issue-143992.rs` fail when it shouldn't
- 90e61db9745f53d9aef21e3ebce0df19cc1389d7: Prefer alias candidates over parameter environment candidates for sizedness, auto and default traits. `tests/ui/sized-hierarchy/incomplete-inference-issue-143992.rs` passes again, but `tests/ui/generic-associated-types/issue-93262.rs` starts failing when it shouldn't
- e412062171925d0b40fdbeb5765c45087bdf0fe7: No longer require that predicates of aliases hold in well-formedness checking of the alias. `tests/ui/generic-associated-types/issue-93262.rs` passes again
Each commit updates all the tests to their new output so it should be easy enough to see what the impact of each change individually is. After all of the changes, tests that pass when they didn't before or vice versa:
- `tests/ui/extern/extern-types-size_of_val.rs`
- Previously passing, but only because of rust-lang/rust#144016, now correctly errors
- `tests/ui/sized-hierarchy/incomplete-inference-issue-143992.rs`
- Previously failing on next solver, only because rust-lang/rust#144016 only applied to the old solver, passing now with 90e61db9745f53d9aef21e3ebce0df19cc1389d7
- `tests/ui/sized-hierarchy/overflow.rs`
- Previously passing, but only because of rust-lang/rust#144016, now correctly errors
- `tests/ui/generic-associated-types/issue-92096.rs`
- Previously passing, due to e412062171925d0b40fdbeb5765c45087bdf0fe7
- Fails to prove `C::Connecting<'placeholder>: Send` which is required when proving that the generator is `Send`. This is an instance of rust-lang/rust#110338.
- `tests/ui/higher-ranked/trait-bounds/normalize-under-binder/norm-before-method-resolution-opaque-type.rs`
- Previously passing, now failing in the next solver, due to 03e0fdab6196e81b44356f42f03b6a0a224cf451
- Expected that this test now fails as ambigious, see [Zulip](https://rust-lang.zulipchat.com/#narrow/channel/144729-t-types/topic/sizedness.20bounds.20in.20explicit_implied_predicates_of.20.28.23142712.29/near/526987384)
This had a crater run in https://github.com/rust-lang/rust/pull/142712#issuecomment-3050358772 alongside some other changes.
r? `@lcnr`
cc rust-lang/rust#142712 (this extracts part of that change)
Update cargo
17 commits in 81c3f77a467359c8be6bc747dc93ec66a6e4ce11..367fd9f213750cd40317803dd0a5a3ce3f0c676d
2025-10-10 18:41:02 +0000 to 2025-10-15 15:01:32 +0000
- test: Don't look for a specfic ANSI color (rust-lang/cargo#16118)
- docs(guide): Clarify where to set config (rust-lang/cargo#16107)
- test(rustfix): re-enable disabled test due to unused variables (rust-lang/cargo#16114)
- Convert the "manifest has no things" warning to annotate_snippets. (rust-lang/cargo#16113)
- doc: make it clearer that `target.<cfg>.linker` is supported (rust-lang/cargo#16112)
- docs(guide): Cover feature-unification (rust-lang/cargo#16108)
- fix(gctx): types are unsupported not unknown (rust-lang/cargo#16109)
- fix(script): Tweak cargo script build-dir / target-dir (rust-lang/cargo#16086)
- docs(gctx): explain Value deserialization step-by-step (rust-lang/cargo#16105)
- docs(guide): Talk about removing unused features (rust-lang/cargo#16085)
- test(config): exercise unsupported TOML types (rust-lang/cargo#16100)
- docs(gctx): a bit more of how config deserialization works (rust-lang/cargo#16094)
- Refactor `Layout` into `BuildDirLayout` and `ArtifactDirLayout` (rust-lang/cargo#16092)
- Add alternative linker to the build performance guide (rust-lang/cargo#15991)
- refactor(gctx): extract error to a module (rust-lang/cargo#16091)
- fix: Fixed nightly tests failing due to unused_variables lint (rust-lang/cargo#16098)
- fix(script): Store cargo script lockfiles in build-dir (rust-lang/cargo#16087)
r? ghost
