The "panic in const if CTFE doesn't know the answer" behavior was discussed to be the desired behavior in #74939, and is currently how the function actually behaves.
I intentionally wrote this documentation to allow for the possibility that a panic might not occur even if the pointer is out of bounds, because of #133700 and other potential changes in the future.
Rollup of 7 pull requests
Successful merges:
- #132939 (Suggest using deref in patterns)
- #133293 (Updates Solaris target information, adds Solaris maintainer)
- #133392 (Fix ICE when multiple supertrait substitutions need assoc but only one is provided)
- #133986 (Add documentation for anonymous pipe module)
- #134022 (Doc: Extend for tuples to be stabilized in 1.85.0)
- #134259 (Clean up `infer_return_ty_for_fn_sig`)
- #134264 (Arbitrary self types v2: Weak & NonNull diagnostics)
r? `@ghost`
`@rustbot` modify labels: rollup
Arbitrary self types v2: Weak & NonNull diagnostics
This builds on top of #134262 which is more urgent to review and merge first. I'll likely rebase this PR once that lands.
This is the first part of the diagnostic enhancements planned for Arbitrary Self Types v2.
Various types can be used as method receivers, such as `Rc<>`, `Box<>` and `Arc<>`. The arbitrary self types v2 work allows further types to be made method receivers by implementing the Receiver trait.
With that in mind, it may come as a surprise to people when certain common types do not implement Receiver and thus cannot be used as a method receiver.
The RFC for arbitrary self types v2 therefore proposes emitting specific
lint hints for these cases:
* `NonNull`
* `Weak`
* Raw pointers
The code already emits a hint for this third case, in that it advises folks that the `arbitrary_self_types_pointers` feature may meet their need. This PR adds diagnostic hints for the `Weak` and `NonNull` cases.
Tracking issue #44874
r? `@wesleywiser`
Clean up `infer_return_ty_for_fn_sig`
The code for lowering fn signatures from HIR currently is structured to prefer the recovery path (where users write `-> _`) over the good path. This PR pulls the recovery code out into a separate fn.
Review w/o whitespace
Doc: Extend for tuples to be stabilized in 1.85.0
I assumed the RUSTC_CURRENT_VERSION would be replaced automatically, but it doesn't look like it on the nightly docs page. Sorry!
Fix ICE when multiple supertrait substitutions need assoc but only one is provided
Dyn traits must have all of their associated types constrained either by:
1. writing them in the dyn trait itself as an associated type bound, like `dyn Iterator<Item = u32>`,
2. A supertrait bound, like `trait ConstrainedIterator: Iterator<Item = u32> {}`, then you may write `dyn ConstrainedIterator` which doesn't need to mention `Item`.
However, the object type lowering code did not consider the fact that there may be multiple supertraits with different substitutions, so it just used the associated type's *def id* as a key for keeping track of which associated types are missing:
1fc691e6dd/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs (L131)
This means that we can have missing associated types when there are mutliple supertraits with different substitutions and only one of them is constrained, like:
```rust
trait Sup<T> {
type Assoc: Default;
}
impl<T: Default> Sup<T> for () {
type Assoc = T;
}
impl<T: Default, U: Default> Dyn<T, U> for () {}
trait Dyn<A, B>: Sup<A, Assoc = A> + Sup<B> {}
```
The above example allows you to name `<dyn Dyn<i32, u32> as Sup<u32>>::Assoc` even though it is not possible to project since it's neither constrained by a manually written projection bound or a supertrait bound. This successfully type-checks, but leads to a codegen ICE since we are not able to project the associated type.
This PR fixes the validation for checking that a dyn trait mentions all of its associated type bounds. This is theoretically a breaking change, since you could technically use that `dyn Dyn<A, B>` type mentionedin the example above without actually *projecting* to the bad associated type, but I don't expect it to ever be relevant to a user since it's almost certainly a bug. This is corroborated with the crater results[^crater], which show no failures[^unknown].
Crater: https://github.com/rust-lang/rust/pull/133392#issuecomment-2508769703Fixes#133388
[^crater]: I cratered this originally with #133397, which is a PR that is stacked on top, then re-ran crater with just the failures from that PR.
[^unknown]: If you look at the crater results, it shows all of the passes as "unknown". I believe this is a crater bug, since looking at the results manually shows them as passes.
Suggest using deref in patterns
Fixes#132784
This changes the following code:
```rs
use std::sync::Arc;
fn main() {
let mut x = Arc::new(Some(1));
match x {
Some(_) => {}
None => {}
}
}
```
to output
```rs
error[E0308]: mismatched types
--> src/main.rs:5:9
|
LL | match x {
| - this expression has type `Arc<Option<{integer}>>`
...
LL | Some(_) => {}
| ^^^^^^^ expected `Arc<Option<{integer}>>`, found `Option<_>`
|
= note: expected struct `Arc<Option<{integer}>>`
found enum `Option<_>`
help: consider dereferencing to access the inner value using the Deref trait
|
LL | match *x {
| ~~
```
instead of
```rs
error[E0308]: mismatched types
--> src/main.rs:5:9
|
4 | match x {
| - this expression has type `Arc<Option<{integer}>>`
5 | Some(_) => {}
| ^^^^^^^ expected `Arc<Option<{integer}>>`, found `Option<_>`
|
= note: expected struct `Arc<Option<{integer}>>`
found enum `Option<_>`
```
This makes it more obvious that a Deref is available, and gives a suggestion on how to use it in order to fix the issue at hand.
Bounds-check with PtrMetadata instead of Len in MIR
Rather than emitting `Len(*_n)` in array index bounds checks, emit `PtrMetadata(copy _n)` instead -- with some asterisks for arrays and `&mut` that need it to be done slightly differently.
We're getting pretty close to removing `Len` entirely, actually. I think just one more PR after this (for slice drop shims).
r? mir
Various types can be used as method receivers, such as Rc<>, Box<> and
Arc<>. The arbitrary self types v2 work allows further types to be made
method receivers by implementing the Receiver trait.
With that in mind, it may come as a surprise to people when certain
common types do not implement Receiver and thus cannot be used as a
method receiver.
The RFC for arbitrary self types v2 therefore proposes emitting specific
lint hints for these cases:
* NonNull
* Weak
* Raw pointers
The code already emits a hint for this third case, in that it advises
folks that the `arbitrary_self_types_pointers` feature may meet their
need. This PR adds diagnostic hints for the Weak and NonNull cases.
Rollup of 6 pull requests
Successful merges:
- #133221 (Add external macros specific diagnostics for check-cfg)
- #133386 (Update linux_musl base to dynamically link the crt by default)
- #134191 (Make some types and methods related to Polonius + Miri public)
- #134227 (Update wasi-sdk used to build WASI targets)
- #134279 ((Re-)return adjustment target if adjust kind is never-to-any)
- #134295 (Encode coroutine-closures in SMIR)
r? `@ghost`
`@rustbot` modify labels: rollup
(Re-)return adjustment target if adjust kind is never-to-any
This PR fixes#134162 where we ICE'd on
```rs
fn main() {
struct X;
let _ = [X] == [panic!(); 2];
}
```
In https://github.com/rust-lang/rust/pull/121208#discussion_r1494187622, there was a change
```diff
- if let Some(adjustments) = self.typeck_results.borrow().adjustments().get(expr.hir_id) {
- let reported = self.dcx().span_delayed_bug(
- expr.span,
- "expression with never type wound up being adjusted",
- );
- return if let [Adjustment { kind: Adjust::NeverToAny, target }] = &adjustments[..] {
- target.to_owned()
- } else {
- Ty::new_error(self.tcx(), reported)
- };
- }
+ if let Some(_) = self.typeck_results.borrow().adjustments().get(expr.hir_id) {
+ self.dcx()
+ .span_bug(expr.span, "expression with never type wound up being adjusted");
+ }
```
It turned out returning the adjustment target if the adjustment kind is `NeverToAny` is necessary, as otherwise we will go through a series of `delay_bug`s and eventually find that we constructed a `TyKind::Error` without having actually emitted an error.
This PR addresses that by re-returning the adjustment target if the adjustment kind is `NeverToAny`, partially reverting this change from #121208.
This PR has two commits:
1. The first commit adds a regression test for #134162, which will ICE (on stable 1.83.0, beta and nightly 2024-12-13).
2. The second commit is the partial revert, which will fix the ICE.
cc `@nnethercote` FYI as this is related to #121208 changes. The changes from #121208 exposed that we lacked test coverage for the code pattern reported in #134162.
Make some types and methods related to Polonius + Miri public
We have a tool, [Aquascope](https://github.com/cognitive-engineering-lab/aquascope/), which uses Polonius and Miri to visualize the compile-time and run-time semantics of a Rust program. Changes in the last few months to both APIs have hidden away details we depend upon. This PR re-exposes some of those details, specifically:
**Polonius:**
- `BorrowSet` and `BorrowData` are added to `rustc_borrowck::consumers`, and their fields are made `pub` instead of `pub(crate)`. We need this to interpret the `BorrowIndex`es generated by Polonius.
- `BorrowSet::build` is now `pub`. We need this because the borrowck API doesn't provide access to the `BorrowSet` constructed during checking.
- `PoloniusRegionVid` is added to `rustc_borrowck::consumers`. We need this because it's also contained in the Polonius facts.
**Miri:**
- `InterpCx::local_to_op` is now a special case of `local_at_frame_to_op`, which allows querying locals in any frame. We need this because we walk the whole stack at each step to collect the state of memory.
- `InterpCx::layout_of_local` is now `pub`. We need this because we need to know the layout of every local at each step.
If these changes go against some design goal for keeping certain types private, please let me know so we can hash out a better solution. Additionally, if there's a better way to document that it's important that certain types stay public, also let me know. For example, `BorrowSet` was previously public but was hidden in 6676cec, breaking our build.
cc ```@RalfJung``` ```@nnethercote``` ```@gavinleroy```
Update linux_musl base to dynamically link the crt by default
However, don't change the behavior of any existing targets at this time. For targets that used the old default, explicitly set `crt_static_default = true`.
This makes it easier for new targets to use the correct defaults while leaving the changing of individual targets to future PRs.
Related to https://github.com/rust-lang/compiler-team/issues/422
Add external macros specific diagnostics for check-cfg
This PR adds specific check-cfg diagnostics for unexpected cfg in external macros.
As well as hiding the some of the Cargo specific help/suggestions as they distraction for external macros and are generally not the right solution.
Follow-up to #132577
`@rustbot` label +L-unexpected_cfgs
r? compiler
Rollup of 6 pull requests
Successful merges:
- #132150 (Fix powerpc64 big-endian FreeBSD ABI)
- #133942 (Clarify how to use `black_box()`)
- #134081 (Try to evaluate constants in legacy mangling)
- #134192 (Remove `Lexer`'s dependency on `Parser`.)
- #134208 (coverage: Tidy up creation of covmap and covfun records)
- #134211 (On Neutrino QNX, reduce the need to set archiver via environment variables)
r? `@ghost`
`@rustbot` modify labels: rollup
(Re-)Implement `impl_trait_in_bindings`
This reimplements the `impl_trait_in_bindings` feature for local bindings.
"`impl Trait` in bindings" serve as a form of *trait* ascription, where the type basically functions as an infer var but additionally registering the `impl Trait`'s trait bounds for the infer type. These trait bounds can be used to enforce that predicates hold, and can guide inference (e.g. for closure signature inference):
```rust
let _: impl Fn(&u8) -> &u8 = |x| x;
```
They are implemented as an additional set of bounds that are registered when the type is lowered during typeck, and then these bounds are tied to a given `CanonicalUserTypeAscription` for borrowck. We enforce these `CanonicalUserTypeAscription` bounds during borrowck to make sure that the `impl Trait` types are sensitive to lifetimes:
```rust
trait Static: 'static {}
impl<T> Static for T where T: 'static {}
let local = 1;
let x: impl Static = &local;
//~^ ERROR `local` does not live long enough
```
r? oli-obk
cc #63065
---
Why can't we just use TAIT inference or something? Well, TAITs in bodies have the problem that they cannot reference lifetimes local to a body. For example:
```rust
type TAIT = impl Display;
let local = 0;
let x: TAIT = &local;
//~^ ERROR `local` does not live long enough
```
That's because TAITs requires us to do *opaque type inference* which is pretty strict, since we need to remap all of the lifetimes of the hidden type to universal regions. This is simply not possible here.
---
I consider this part of the "impl trait everywhere" experiment. I'm not certain if this needs yet another lang team experiment.
Without doing so, we'll run into a series of delayed bugs then find that
we have a `TyKind::Error` constructed yet fail to emit an error.
This partially reverts a change in
<https://github.com/rust-lang/rust/pull/121208> related to never type
adjustments in expr typecheck errors.
Rollup of 8 pull requests
Successful merges:
- #134252 (Fix `Path::is_absolute` on Hermit)
- #134254 (Fix building `std` for Hermit after `c_char` change)
- #134255 (Update includes in `/library/core/src/error.rs`.)
- #134261 (Document the symbol Visibility enum)
- #134262 (Arbitrary self types v2: adjust diagnostic.)
- #134265 (Rename `ty_def_id` so people will stop using it by accident)
- #134271 (Arbitrary self types v2: better feature gate test)
- #134274 (Add check-pass test for `&raw`)
r? `@ghost`
`@rustbot` modify labels: rollup
On Neutrino QNX, reduce the need to set archiver via environment variables
This adds support for automatically selecting the correct `ar` tool when compiling for Neutrino QNX.
Once https://github.com/rust-lang/cc-rs/pull/1319 is merged and a new cc version is integrated, all environment variables of the [Neutrino documentation](https://github.com/rust-lang/rust/blob/stable/src/doc/rustc/src/platform-support/nto-qnx.md) can be removed.
CC: ````````@jonathanpallant```````` ````````@japaric```````` ````````@gh-tr```````` ````````@AkhilTThomas````````
coverage: Tidy up creation of covmap and covfun records
This is a small follow-up to #134163 that mostly just inlines and renames some variables, and adds a few comments.
It also slightly defers the creation of the LLVM value that holds the filename table, to just before the value is needed.
---
try-job: x86_64-mingw-2
try-job: dist-x86_64-linux
Remove `Lexer`'s dependency on `Parser`.
Lexing precedes parsing, as you'd expect: `Lexer` creates a `TokenStream` and `Parser` then parses that `TokenStream`.
But, in a horrendous violation of layering abstractions and common sense, `Lexer` depends on `Parser`! The `Lexer::unclosed_delim_err` method does some error recovery that relies on creating a `Parser` to do some post-processing of the `TokenStream` that the `Lexer` just created.
This commit just removes `unclosed_delim_err`. This change removes `Lexer`'s dependency on `Parser`, and also means that `lex_token_tree`'s return value can have a more typical form.
The cost is slightly worse error messages in two obscure cases, as shown in these tests:
- tests/ui/parser/brace-in-let-chain.rs: there is slightly less explanation in this case involving an extra `{`.
- tests/ui/parser/diff-markers/unclosed-delims{,-in-macro}.rs: the diff marker detection is no longer supported (because that detection is implemented in the parser).
In my opinion this cost is outweighed by the magnitude of the code cleanup.
r? ```````@chenyukang```````
Try to evaluate constants in legacy mangling
Best reviewed commit by commit.
It seems kind of odd to treat literals differently from unevaluated free constants. So let's evaluate those constants and only fall back to `_` rendering if that fails to result in an integral constant
Clarify how to use `black_box()`
Closes#133923.
r? libs
^ (I think that's the right group, this is my first time!)
This PR adds further clarification on the [`black_box()`](https://doc.rust-lang.org/stable/std/hint/fn.black_box.html) documentation. Specifically, it teaches _how_ to use it, instead of just _when_ to use it.
I tried my best to make it clear and accurate, but a lot of my information is sourced from https://github.com/rust-lang/rust-clippy/issues/12707 and [manually inspecting assembly](https://godbolt.org/). Please tell me if I got anything wrong!
Add check-pass test for `&raw`
`&raw` denotes a normal/non-raw borrow of the path `raw`, not the start of raw borrow since it's not followed by either `const` or `mut`. Ensure this (and variants) will never regress!
When I saw the open diagnostic issue https://github.com/rust-lang/rust/issues/133231 (better parse error (recovery) on `&raw <expr>`), it made me think that we have to make sure that we will never commit too early/overzealously(†) when encountering the sequence `&raw`, even during parse error recovery!
Modifying the parser to eagerly treat `&raw` as the start of a raw borrow expr only lead to a single UI test failing, namely [tests/ui/enum-discriminant/ptr_niche.rs](4847d6a9d0/tests/ui/enum-discriminant/ptr_niche.rs). However, this is just coincidental — it didn't *intentionally* test this edge case of the grammar.
---
†: With "eager" I mean something like:
```patch
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 0904a42d8a4..68d690fd602 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
`@@` -873,11 +873,16 `@@` fn error_remove_borrow_lifetime(&self, span: Span, lt_span: Span) {
/// Parse `mut?` or `raw [ const | mut ]`.
fn parse_borrow_modifiers(&mut self) -> (ast::BorrowKind, ast::Mutability) {
- if self.check_keyword(kw::Raw) && self.look_ahead(1, Token::is_mutability) {
+ if self.eat_keyword(kw::Raw) {
// `raw [ const | mut ]`.
- let found_raw = self.eat_keyword(kw::Raw);
- assert!(found_raw);
- let mutability = self.parse_const_or_mut().unwrap();
+ let mutability = self.parse_const_or_mut().unwrap_or_else(|| {
+ let span = self.prev_token.span;
+ self.dcx().emit_err(ExpectedMutOrConstInRawBorrowExpr {
+ span,
+ after_ampersand: span.shrink_to_hi(),
+ });
+ ast::Mutability::Not
+ });
(ast::BorrowKind::Raw, mutability)
} else {
// `mut?`
```
---
r? compiler
Arbitrary self types v2: better feature gate test
Slight improvement to the test for the `arbitrary_self_types_pointers` feature gate, to ensure it's independent of the `arbitrary_self_types` gate.
Part of #44874
r? `@wesleywiser`
Rename `ty_def_id` so people will stop using it by accident
This function is just for cycle detection, but people keep using it because they think it's the right way of getting the def id from a `Ty` (and I can't blame them necessarily).
Arbitrary self types v2: adjust diagnostic.
The recently landed PR #132961 to adjust arbitrary self types was a bit overenthusiastic, advising folks to use the new Receiver trait even before it's been stabilized. Revert to the older wording of the lint in such cases.
Tracking issue #44874
r? ``@wesleywiser``
Update includes in `/library/core/src/error.rs`.
This PR removes the `crate::fmt::Result` include in `/library/core/src/error.rs`.
The main issue with this `use` statement is that it shadows the `Result` type from the prelude (i.e. `crate::result::Result`). This indirectly makes all docs references to `Result` in this module point to the wrong type (but only in `core::error` - not `std::error`, wherein this include isn't present to begin with).
Fixes: #134169
A bunch of cleanups (part 2)
Just like https://github.com/rust-lang/rust/pull/133567 these were all found while looking at the respective code, but are not blocking any other changes I want to make in the short term.
rustc_borrowck: Stop suggesting the invalid syntax `&mut raw const`
A legitimate suggestion would be to change from
&raw const val
to
&raw mut val
But until we have figured out how to make that happen we should at least
stop suggesting invalid syntax.
I recommend review commit-by-commit.
Part of #127562
