Implement edition 2024 match ergonomics restrictions
This implements the minimalest version of [match ergonomics for edition 2024](https://rust-lang.github.io/rfcs/3627-match-ergonomics-2024.html). This minimal version makes it an error to ever reset the default binding mode. The implemented proposal is described precisely [here](https://hackmd.io/zUqs2ISNQ0Wrnxsa9nhD0Q#RFC-3627-nano), where it is called "RFC 3627-nano".
Rules:
- Rule 1C: When the DBM (default binding mode) is not `move` (whether or not behind a reference), writing `mut`, `ref`, or `ref mut` on a binding is an error.
- Rule 2C: Reference patterns can only match against references in the scrutinee when the DBM is `move`.
This minimal version is forward-compatible with the main proposals for match ergonomics 2024: [RFC3627](https://rust-lang.github.io/rfcs/3627-match-ergonomics-2024.html) itself, the alternative [rule 4-early variant](https://rust-lang.github.io/rfcs/3627-match-ergonomics-2024.html), and [others](https://hackmd.io/zUqs2ISNQ0Wrnxsa9nhD0Q). The idea is to give us more time to iron out a final proposal.
This includes a migration lint that desugars any offending pattern into one that doesn't make use of match ergonomics. Such patterns have identical meaning across editions.
This PR insta-stabilizes the proposed behavior onto edition 2024.
r? `@ghost`
Tracking:
- https://github.com/rust-lang/rust/issues/123076
Check ABI target compatibility for function pointers
Tracking issue: https://github.com/rust-lang/rust/issues/130260
Related tracking issue: #87678
Compatibility of an ABI for a target was previously only performed on function definitions and `extern` blocks. This PR adds it also to function pointers to be consistent.
This might have broken some of the `tests/ui/` depending on the platform, so a try run seems like a good idea.
Also this might break existing code, because we now emit extra errors. Does this require a crater run?
# Example
```rust
// build with: --target=x86_64-unknown-linux-gnu
// These raise E0570
extern "thiscall" fn foo() {}
extern "thiscall" { fn bar() }
// This did not raise any error
fn baz(f: extern "thiscall" fn()) { f() }
```
# Open Questions
* [x] Should this report a future incompatibility warning like #87678 ?
* [ ] Is this the best place to perform the check?
add `naked_asm!` macro for use in `#[naked]` functions
tracking issue: https://github.com/rust-lang/rust/issues/90957
Adds the `core::arch::naked_asm` macro, to be used in `#[naked]` functions, but providing better error messages and a place to explain the restrictions on assembly in naked functions.
This PR does not yet require that the `naked_asm!` macro is used inside of `#[naked]` functions:
- the `asm!` macro can still be used in `#[naked]` functions currently, with the same restrictions and error messages as before.
- the `naked_asm!` macro can be used outside of `#[naked]` functions. It has not yet been decided whether that should be allowed long-term.
In this PR, the parsing code of `naked_asm!` now enforces the restrictions on assembly in naked functions, with the exception of checking that the `noreturn` option is specified. It also has not currently been decided if `noreturn` should be implicit or not.
This PR looks large because it touches a bunch of tests. The code changes are mostly straightforward I think: we now have 3 flavors of assembly macro, and that information must be propagated through the parsing code and error messages.
cc `@Lokathor`
r? `@Amanieu`
- fix for divergence
- fix error message
- fix another cranelift test
- fix some cranelift things
- don't set the NORETURN option for naked asm
- fix use of naked_asm! in doc comment
- fix use of naked_asm! in run-make test
- use `span_bug` in unreachable branch
Make deprecated_cfg_attr_crate_type_name a hard error
Turns the forward compatibility lint added by #83744 into a hard error, so now, while the `#![crate_name]` and `#![crate_type]` attributes are still allowed in raw form, they are now forbidden to be nested inside a `#![cfg_attr()]` attribute.
The following will now be an error:
```Rust
#![cfg_attr(foo, crate_name = "foobar")]
#![cfg_attr(foo, crate_type = "bin")]
```
This code will continue working and is not deprecated:
```Rust
#![crate_name = "foobar"]
#![crate_type = "lib"]
```
The reasoning for this is explained in #83744: it allows us to not have to cfg-expand in order to determine the crate's type and name.
As of filing the PR, exactly two years have passed since #99784 has been merged, which has turned the lint's default warning level into an error, so there has been ample time to move off the now-forbidden syntax.
cc #91632 - tracking issue for the lint
Make some lint doctests compatible with `--stage=0`
Currently, running `x test compiler --stage=0` (with `rust.parallel-compiler=false` to avoid other problems) results in two failures, because these lint doctests aren't compatible with the current stage0 compiler.
In theory, the more “correct” solution would be to wrap the opening triple-backtick line in `#[cfg_attr(not(bootstrap), doc = "..."]`. However, that causes a few practical problems:
- `tidy` doesn't understand that syntax, and miscounts the number of backticks in the comment block.
- `lint-docs` doesn't understand that syntax, and thinks it's trying to declare the lint name.
- Working around the above problems would cause more work and more confusion for whoever does the next bootstrap beta bump.
So instead this PR adds some bootstrap gates inside the individual doctests, which end up producing the desired behaviour, and are straightforward to remove.
Implement raw lifetimes and labels (`'r#ident`)
This PR does two things:
1. Reserve lifetime prefixes, e.g. `'prefix#lt` in edition 2021.
2. Implements raw lifetimes, e.g. `'r#async` in edition 2021.
This PR additionally extends the `keyword_idents_2024` lint to also check lifetimes.
cc `@traviscross`
r? parser
Rewrite lint_expectations in a single pass.
This PR aims at reducing the perf regression from https://github.com/rust-lang/rust/pull/120924#issuecomment-2202486203 with drive-by simplifications.
Basically, instead of using the lint level builder, which is slow, this PR splits `lint_expectations` logic in 2:
- listing the `LintExpectations` is done in `shallow_lint_levels_on`, on a per-owner basis;
- building the unstable->stable expectation id map is done by iterating on attributes.
r? ghost for perf
Deny `wasm_c_abi` lint to nudge the last 25%
This shouldn't affect projects indirectly depending on wasm-bindgen because cargo passes `--cap-lints=allow` when building dependencies.
The motivation is that the ecosystem has mostly taken up the versions of wasm-bindgen that are compatible in general, but ~25% or so of recent downloads remain on lower versions. However, this change might still be unnecessarily disruptive. I mostly propose it as a discussion point.
make writes_through_immutable_pointer a hard error
This turns the lint added in https://github.com/rust-lang/rust/pull/118324 into a hard error. This has been reported in cargo's future-compat reports since Rust 1.76 (released in February). Given that const_mut_refs is still unstable, it should be impossible to even hit this error on stable: we did accidentally stabilize some functions that can cause this error, but that got reverted in https://github.com/rust-lang/rust/pull/117905. Still, let's do a crater run just to be sure.
Given that this should only affect unstable code, I don't think it needs an FCP, but let's Cc ``@rust-lang/lang`` anyway -- any objection to making this unambiguous UB into a hard error during const-eval? This can be viewed as part of https://github.com/rust-lang/rust/pull/129195 which is already nominated for discussion.
bump conflicting_repr_hints lint to be shown in dependencies
This has been a future compatibility lint for years, let's bump it up to be shown in dependencies (so that hopefully we can then make it a hard error fairly soon).
Cc https://github.com/rust-lang/rust/issues/68585
Stabilize `unsafe_attributes`
# Stabilization report
## Summary
This is a tracking issue for the RFC 3325: unsafe attributes
We are stabilizing `#![feature(unsafe_attributes)]`, which makes certain attributes considered 'unsafe', meaning that they must be surrounded by an `unsafe(...)`, as in `#[unsafe(no_mangle)]`.
RFC: rust-lang/rfcs#3325
Tracking issue: #123757
## What is stabilized
### Summary of stabilization
Certain attributes will now be designated as unsafe attributes, namely, `no_mangle`, `export_name`, and `link_section` (stable only), and these attributes will need to be called by surrounding them in `unsafe(...)` syntax. On editions prior to 2024, this is simply an edition lint, but it will become a hard error in 2024. This also works in `cfg_attr`, but `unsafe` is not allowed for any other attributes, including proc-macros ones.
```rust
#[unsafe(no_mangle)]
fn a() {}
#[cfg_attr(any(), unsafe(export_name = "c"))]
fn b() {}
```
For a table showing the attributes that were considered to be included in the list to require unsafe, and subsequent reasoning about why each such attribute was or was not included, see [this comment here](https://github.com/rust-lang/rust/pull/124214#issuecomment-2124753464)
## Tests
The relevant tests are in `tests/ui/rust-2024/unsafe-attributes` and `tests/ui/attributes/unsafe`.
turn `invalid_type_param_default` into a `FutureReleaseErrorReportInDeps`
`````@rust-lang/types````` I assume the plan is still to disallow this? It has been a future-compat lint for a long time, seems ripe to go for hard error.
However, turns out that outright removing it right now would lead to [tons of crater regressions](https://github.com/rust-lang/rust/pull/127655#issuecomment-2228285460), so for now this PR just makes this future-compat lint show up in cargo's reports, so people are warned when they use a dependency that is affected by this.
Fixes https://github.com/rust-lang/rust/issues/27336 by removing the feature gate (so there's no way to silence the lint even on nightly)
CC https://github.com/rust-lang/rust/issues/36887
Add `REDUNDANT_IMPORTS` lint for new redundant import detection
Defaults to Allow for now. Stacked on #123744 to avoid merge conflict, but much easier to review all as one.
r? petrochenkov
Remove `crate_level_only` from `ELIDED_LIFETIMES_IN_PATHS`
As far as I can tell, we provide the right node id to the `ELIDED_LIFETIMES_IN_PATHS` lint:
f8060d282d/compiler/rustc_resolve/src/late.rs (L2015-L2027)
So I've gone ahead and removed the restriction from this lint.
