Infer type in irrefutable slice patterns with fixed length as array
Fixes https://github.com/rust-lang/rust/issues/76342
In irrefutable slice patterns with a fixed length, we can infer the type as an array type. We now choose to prefer some implementations over others, e.g. in:
```
struct Zeroes;
const ARR: [usize; 2] = [0; 2];
const ARR2: [usize; 2] = [2; 2];
impl Into<&'static [usize; 2]> for Zeroes {
fn into(self) -> &'static [usize; 2] {
&ARR
}
}
impl Into<&'static [usize]> for Zeroes {
fn into(self) -> &'static [usize] {
&ARR2
}
}
fn main() {
let &[a, b] = Zeroes.into();
}
```
We now prefer the impl candidate `impl Into<&'static [usize; 2]> for Zeroes`, it's not entirely clear to me that this is correct, but given that the slice impl would require a type annotation anyway, this doesn't seem unreasonable.
r? `@lcnr`
Fix suggestion spans for expr from macro expansions
### Issue #112007: rustc shows expanded `writeln!` macro in code suggestion
#### Before This PR
```
help: consider using a semicolon here
|
6 | };
| +
help: you might have meant to return this value
--> C:\Users\hayle\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\macros\mod.rs:557:9
|
55| return $dst.write_fmt($crate::format_args_nl!($($arg)*));
| ++++++ +
```
#### After This PR
```
help: consider using a semicolon here
|
LL | };
| +
help: you might have meant to return this value
|
LL | return writeln!(w, "but not here");
| ++++++ +
```
### Issue #110017: `format!` `.into()` suggestion deletes the `format` macro
#### Before This PR
```
help: call `Into::into` on this expression to convert `String` into `Box<dyn std::error::Error>`
--> /Users/eric/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/macros.rs:121:12
|
12| res.into()
| +++++++
```
#### After This PR
```
help: call `Into::into` on this expression to convert `String` into `Box<dyn std::error::Error>`
|
LL | Err(format!("error: {x}").into())
| +++++++
```
---
Fixes#112007.
Fixes#110017.
Miscellaneous HIR typeck nits
Remove some check functions that only have one usage
Also remove `Expectation::IsLast`, which was both undocumented, and was also made redundant by my cleanup/fix in #103987😸
Temporarily eholk from review rotation
I'm going to be out for the rest of this week and then all of next week, and I generally haven't had the bandwidth to do much in the way of reviewing lately anyway. I'm going to remove myself for the review queue at least until I'm back from vacation and have some time to get a few other things in better shape.
r? `@wesleywiser`
Clarify documentation for `CStr`
* Better differentiate summaries for `from_bytes_until_nul` and `from_bytes_with_nul`
* Add some links where they may be helpful
Suggest `x build library` for a custom toolchain that fails to load `core`
Fixes#113222
The nicer suggestion for dev-channel won't be emitted if `-Z ui-testing` enabled. IMO, this is acceptable for now.
It's the same as `Delimiter`, minus the `Invisible` variant. I'm
generally in favour of using types to make impossible states
unrepresentable, but this one feels very low-value, and the conversions
between the two types are annoying and confusing.
Look at the change in `src/tools/rustfmt/src/expr.rs` for an example:
the old code converted from `MacDelimiter` to `Delimiter` and back
again, for no good reason. This suggests the author was confused about
the types.
Revert #113588 to fix bootstrap timings
This reverts #113588 which seems to have broken perf's bootstrap timings via some git issue
https://github.com/rust-lang/rust/pull/114318#issuecomment-1660807886 show a newly broken benchmark, the error at the time was
```
fatal: Path 'src/ci/channel' exists on disk, but not in 'e62323df22ecf9c163023132d17b7114f68b72e8'.
thread 'main' panicked at 'command did not execute successfully: cd "/home/collector/rustc-perf/rust" && "git" "show" "e62323df22ecf9c163023132d17b7114f68b72e8:src/ci/channel"
expected success, got: exit status: 128', config.rs:1786:27
```
If this lands, it will reopen#101907 and annoy miri, but it could actually be an issue that would appear during the next bootstrap bump, not just rustc-perf today.
r? `@ghost`
Remove `constness` from `TraitPredicate`
Any ICEs or compiler errors created by this PR are expected and intended to be fixed in the future.
r? `@oli-obk`
cc #110395
Rollup of 5 pull requests
Successful merges:
- #114079 (Use `upvar_tys` in more places, make it return a list)
- #114166 (Add regression test for resolving `--extern libc=test.rlib`)
- #114321 (get auto traits for parallel rustc)
- #114335 (fix and extend ptr_comparison test)
- #114347 (x.py print more detailed format files and untracked files count)
r? `@ghost`
`@rustbot` modify labels: rollup
Improve `invalid_reference_casting` lint
This PR is a follow-up to https://github.com/rust-lang/rust/pull/111567 and https://github.com/rust-lang/rust/pull/113422.
This PR does multiple things:
- First it adds support for deferred de-reference, the goal is to support code like this, where the casting and de-reference are not done on the same expression
```rust
let myself = self as *const Self as *mut Self;
*myself = Self::Ready(value);
```
- Second it does not lint anymore on SB/TB UB code by only checking assignments (`=`, `+=`, ...) and creation of mutable references `&mut *`
- Thirdly it greatly improves the diagnostics in particular for cast from `&mut` to `&mut` or assignments
- ~~And lastly it renames the lint from `cast_ref_to_mut` to `invalid_reference_casting` which is more consistent with the ["rules"](https://github.com/rust-lang/rust-clippy/issues/2845) and also more consistent with what the lint checks~~ *https://github.com/rust-lang/rust/pull/113422*
This PR is best reviewed commit by commit.
r? compiler
Miri: fix error on dangling pointer inbounds offset
We used to claim that the pointer was "dereferenced", but that is just not true.
Can be reviewed commit-by-commit. The first commit is an unrelated rename that didn't seem worth splitting into its own PR.
r? `@oli-obk`
coverage: Consolidate FFI types into one module
Coverage FFI types were historically split across two modules, because some of them were needed by code in `rustc_codegen_ssa`.
Now that all of the coverage codegen code has been moved into `rustc_codegen_llvm` (#113355), it's possible to move all of the FFI types into a single module, making it easier to see all of them at once.
---
This PR only moves code and adjusts imports; there should be no functional changes.
Coverage FFI types were historically split across two modules, because some of
them were needed by code in `rustc_codegen_ssa`.
Now that all of the coverage codegen code has been moved into
`rustc_codegen_llvm` (#113355), it's possible to move all of the FFI types into
a single module, making it easier to see all of them at once.
Rollup of 6 pull requests
Successful merges:
- #114178 (Account for macros when suggesting a new let binding)
- #114199 (Don't unsize coerce infer vars in select in new solver)
- #114301 (Don't check unnecessarily that impl trait is RPIT)
- #114314 (Tweaks to `adt_sized_constraint`)
- #114322 (Fix invalid slice coercion suggestion reported in turbofish)
- #114340 ([rustc_attr][nit] Replace `filter` + `is_some` with `map_or`.)
r? `@ghost`
`@rustbot` modify labels: rollup
Fix invalid slice coercion suggestion reported in turbofish
This PR fixes the invalid slice coercion suggestion reported in turbofish and inferred generics by not emitting them.
Fixes https://github.com/rust-lang/rust/issues/110063
Don't check unnecessarily that impl trait is RPIT
We have this random `return_type_impl_trait` function to detect if a function returns an RPIT which is used in outlives suggestions, but removing it doesn't actually change any diagnostics. Let's just remove it.
Also, suppress a spurious outlives error from a ReError.
Fixes#114274
Account for macros when suggesting a new let binding
Provide a structured suggestion when the expression comes from a macro expansion:
```
error[E0716]: temporary value dropped while borrowed
--> $DIR/borrowck-let-suggestion.rs:2:17
|
LL | let mut x = vec![1].iter();
| ^^^^^^^ - temporary value is freed at the end of this statement
| |
| creates a temporary value which is freed while still in use
LL |
LL | x.use_mut();
| - borrow later used here
|
= note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider using a `let` binding to create a longer lived value
|
LL ~ let binding = vec![1];
LL ~ let mut x = binding.iter();
|
```
WASI threads, implementation of wasm32-wasi-preview1-threads target
This PR adds a target proposed in https://github.com/rust-lang/compiler-team/issues/574 by `@abrown` and implementation of `std:🧵:spawn` for the target `wasm32-wasi-preview1-threads`
### Tier 3 Target Policy
As tier 3 targets, the new targets are required to adhere to [the tier 3 target policy](https://doc.rust-lang.org/nightly/rustc/target-tier-policy.html#tier-3-target-policy) requirements. This section quotes each requirement in entirety and describes how they are met.
> - A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)
See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/pull/112922/files#diff-a48ee9d94f13e12be24eadd08eb47b479c153c340eeea4ef22276d876dfd4f3e).
> - Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.
> - Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.
If possible, use only letters, numbers, dashes and underscores for the name. Periods (.) are known to cause issues in Cargo.
The target is using the same name for $ARCH=wasm32 and $OS=wasi as existing Rust targets. The suffix `preview1` introduced to accurately set expectations because eventually this target will be deprecated and follows [MCP 607](https://github.com/rust-lang/compiler-team/issues/607). The suffix `threads` indicates that it’s an extension that enables threads to the existing target and it follows [MCP 574](https://github.com/rust-lang/compiler-team/issues/574) which describes the rationale behind introducing a separate target.
> - Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.
> - The target must not introduce license incompatibilities.
> - Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0).
> - The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.
> - Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.
> - "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.
This PR does not introduce any new dependency.
The new target doesn’t support building host tools.
> Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.
The full standard library is available for this target as it’s an extension to an existing target that has already supported it.
> The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary.
Only manual test running is supported at the moment with some tweaks in the test runner codebase. For build and running tests see [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/pull/112922/files#diff-a48ee9d94f13e12be24eadd08eb47b479c153c340eeea4ef22276d876dfd4f3e).
> - Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.
> - This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements.
> - Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.
> - Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.
> - Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.
> - In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.
I acknowledge these requirements and intend to ensure they are met.
Similar to the last commit, it's more of a `Parser`-level concern than a
`TokenCursor`-level concern. And the struct size reductions are nice.
After this change, `TokenCursor` is as minimal as possible (two fields
and two methods) which is nice.
