Port the proc macro attributes to the new attribute parsing infrastructure
Ports `#[proc_macro]`, `#[proc_macro_attribute]`, `#[proc_macro_derive]` and `#[rustc_builtin_macro]` to the new attribute parsing infrastructure for https://github.com/rust-lang/rust/issues/131229#issuecomment-2971351163
I've split this PR into commits for reviewability, and left some comments to clarify things
I did 4 related attributes in one PR because they share a lot of their code and logic, and doing them separately is kind of annoying as I need to leave both the old and new parsing in place then.
r? ``@oli-obk``
cc ``@jdonszelmann``
Because doc code does not get automatically formatted, some doc code has
creative placements of comments that automatic formatting can't handle.
Reformat those comments to make the resulting code support standard Rust
formatting without breaking; this is generally an improvement to
readability as well.
Some comments are not indented to the prevailing indent, and are instead
aligned under some bit of code. Indent them to the prevailing indent,
and put spaces *inside* the comments to align them with code.
Some comments span several lines of code (which aren't the line the
comment is about) and expect alignment. Reformat them into one comment
not broken up by unrelated intervening code.
Some comments are placed on the same line as an opening brace, placing
them effectively inside the subsequent block, such that formatting would
typically format them like a line of that block. Move those comments to
attach them to what they apply to.
Some comments are placed on the same line as a one-line braced block,
effectively attaching them to the closing brace, even though they're
about the code inside the block. Reformat to make sure the comment will
stay on the same line as the code it's commenting.
Ensure we codegen the main fn
This fixes two bugs. The one that was identified in the linked issue is that when we have a `main` function, mono collection didn't consider it as an extra collection root.
The other is that since CGU partitioning doesn't know about the call edges between the entrypoint functions, naively it can put them in different CGUs and mark them all as internal. Which would result in LLVM just deleting all of them. There was an existing hack to exclude `lang = "start"` from internalization, which I've extended to include `main`.
Fixes https://github.com/rust-lang/rust/issues/144052
Mitigate `#[align]` name resolution ambiguity regression with a rename
Mitigates beta regression rust-lang/rust#143834 after a beta backport.
### Background on the beta regression
The name resolution regression arises due to rust-lang/rust#142507 adding a new feature-gated built-in attribute named `#[align]`. However, unfortunately even [introducing new feature-gated unstable built-in attributes can break user code](https://www.github.com/rust-lang/rust/issues/134963) such as
```rs
macro_rules! align {
() => {
/* .. */
};
}
pub(crate) use align; // `use` here becomes ambiguous
```
### Mitigation approach
This PR renames `#[align]` to `#[rustc_align]` to mitigate the beta regression by:
1. Undoing the introduction of a new built-in attribute with a common name, i.e. `#[align]`.
2. Renaming `#[align]` to `#[rustc_align]`. The renamed attribute being `rustc_align` will not introduce new stable breakages, as attributes beginning with `rustc` are reserved and perma-unstable. This does mean existing nightly code using `fn_align` feature will additionally need to specify `#![feature(rustc_attrs)]`.
This PR is very much a short-term mitigation to alleviate time pressure from having to fully fix the current limitation of inevitable name resolution regressions that would arise from adding any built-in attributes. Long-term solutions are discussed in [#t-lang > namespacing macro attrs to reduce conflicts with new adds](https://rust-lang.zulipchat.com/#narrow/channel/213817-t-lang/topic/namespacing.20macro.20attrs.20to.20reduce.20conflicts.20with.20new.20adds/with/529249622).
### Alternative mitigation options
[Various mitigation options were considered during the compiler triage meeting](https://github.com/rust-lang/rust/issues/143834#issuecomment-3084415277), and those consideration are partly reproduced here:
- Reverting the PR doesn't seem very minimal/trivial, and carries risks of its own.
- Rename to a less-common but aim-to-stabilization name is itself not safe nor convenient, because (1) that risks introducing new regressions (i.e. ambiguity against the new name), and (2) lang would have to FCP the new name hastily for the mitigation to land timely and have a chance to be backported. This also makes the path towards stabilization annoying.
- Rename the attribute to a rustc attribute, which will be perma-unstable and does not cause new ambiguities in stable code.
- This alleviates the time pressure to address *this* regression, or for lang to have to rush an FCP for some new name that can still break user code.
- This avoids backing out a whole implementation.
### Review advice
This PR is best reviewed commit-by-commit.
- Commit 1 adds a test `tests/ui/attributes/fn-align-nameres-ambiguity-143834.rs` which demonstrates the current name resolution regression re. `align`. This test fails against current master.
- Commit 2 carries out the renames and test reblesses. Notably, commit 2 will cause `tests/ui/attributes/fn-align-nameres-ambiguity-143834.rs` to change from fail (nameres regression) to pass.
This PR, if the approach still seems acceptable, will need a beta-backport to address the beta regression.
From `#[align]` -> `#[rustc_align]`. Attributes starting with `rustc`
are always perma-unstable and feature-gated by `feature(rustc_attrs)`.
See regression RUST-143834.
For the underlying problem where even introducing new feature-gated
unstable built-in attributes can break user code such as
```rs
macro_rules! align {
() => {
/* .. */
};
}
pub(crate) use align; // `use` here becomes ambiguous
```
refer to RUST-134963.
Since the `#[align]` attribute is still feature-gated by
`feature(fn_align)`, we can rename it as a mitigation. Note that
`#[rustc_align]` will obviously mean that current unstable user code
using `feature(fn_aling)` will need additionally `feature(rustc_attrs)`,
but this is a short-term mitigation to buy time, and is expected to be
changed to a better name with less collision potential.
See
<https://rust-lang.zulipchat.com/#narrow/channel/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202025-07-17/near/529290371>
where mitigation options were considered.
Show the offset, length and memory of uninit read errors
r? ``@RalfJung``
I want to improve memory dumps in general. Not sure yet how to do so best within rust diagnostics, but in a perfect world I could generate a dummy in-memory file (that contains the rendered memory dump) that we then can then provide regular rustc `Span`s to. So we'd basically report normal diagnostics for them with squiggly lines and everything.
Split-up stability_index query
This PR aims to move deprecation and stability processing away from the monolithic `stability_index` query, and directly implement `lookup_{deprecation,stability,body_stability,const_stability}` queries.
The basic idea is to:
- move per-attribute sanity checks into `check_attr.rs`;
- move attribute compatibility checks into the `MissingStabilityAnnotations` visitor;
- progressively dismantle the `Annotator` visitor and the `stability_index` query.
The first commit contains functional change, and now warns when `#[automatically_derived]` is applied on a non-trait impl block. The other commits should not change visible behaviour.
Perf in https://github.com/rust-lang/rust/pull/143845#issuecomment-3066308630 shows small but consistent improvement, except for unused-warnings case. That case being a stress test, I'm leaning towards accepting the regression.
This PR changes `check_attr`, so has a high conflict rate on that file. This should not cause issues for review.
Rollup of 11 pull requests
Successful merges:
- rust-lang/rust#142300 (Disable `tests/run-make/mte-ffi` because no CI runners have MTE extensions enabled)
- rust-lang/rust#143271 (Store the type of each GVN value)
- rust-lang/rust#143293 (fix `-Zsanitizer=kcfi` on `#[naked]` functions)
- rust-lang/rust#143719 (Emit warning when there is no space between `-o` and arg)
- rust-lang/rust#143846 (pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests)
- rust-lang/rust#143891 (Port `#[coverage]` to the new attribute system)
- rust-lang/rust#143967 (constify `Option` methods)
- rust-lang/rust#144008 (Fix false positive double negations with macro invocation)
- rust-lang/rust#144010 (Boostrap: add warning on `optimize = false`)
- rust-lang/rust#144049 (rustc-dev-guide subtree update)
- rust-lang/rust#144056 (Copy GCC sources into the build directory even outside CI)
r? `@ghost`
`@rustbot` modify labels: rollup
fix `-Zsanitizer=kcfi` on `#[naked]` functions
fixes https://github.com/rust-lang/rust/issues/143266
With `-Zsanitizer=kcfi`, indirect calls happen via generated intermediate shim that forwards the call. The generated shim preserves the attributes of the original, including `#[unsafe(naked)]`. The shim is not a naked function though, and violates its invariants (like having a body that consists of a single `naked_asm!` call).
My fix here is to match on the `InstanceKind`, and only use `codegen_naked_asm` when the instance is not a `ReifyShim`. That does beg the question whether there are other `InstanceKind`s that could come up. As far as I can tell the answer is no: calling via `dyn` seems to work find, and `#[track_caller]` is disallowed in combination with `#[naked]`.
r? codegen
````@rustbot```` label +A-naked
cc ````@maurer```` ````@rcvalle````
`-Zhigher-ranked-assumptions`: Consider WF of coroutine witness when proving outlives assumptions
### TL;DR
This PR introduces an unstable flag `-Zhigher-ranked-assumptions` which tests out a new algorithm for dealing with some of the higher-ranked outlives problems that come from auto trait bounds on coroutines. See:
* rust-lang/rust#110338
While it doesn't fix all of the issues, it certainly fixed many of them, so I'd like to get this landed so people can test the flag on their own code.
### Background
Consider, for example:
```rust
use std::future::Future;
trait Client {
type Connecting<'a>: Future + Send
where
Self: 'a;
fn connect(&self) -> Self::Connecting<'_>;
}
fn call_connect<C>(c: C) -> impl Future + Send
where
C: Client + Send + Sync,
{
async move { c.connect().await }
}
```
Due to the fact that we erase the lifetimes in a coroutine, we can think of the interior type of the async block as something like: `exists<'r, 's> { C, &'r C, C::Connecting<'s> }`. The first field is the `c` we capture, the second is the auto-ref that we perform on the call to `.connect()`, and the third is the resulting future we're awaiting at the first and only await point. Note that every region is uniquified differently in the interior types.
For the async block to be `Send`, we must prove that both of the interior types are `Send`. First, we have an `exists<'r, 's>` binder, which needs to be instantiated universally since we treat the regions in this binder as *unknown*[^exist]. This gives us two types: `{ &'!r C, C::Connecting<'!s> }`. Proving `&'!r C: Send` is easy due to a [`Send`](https://doc.rust-lang.org/nightly/std/marker/trait.Send.html#impl-Send-for-%26T) impl for references.
Proving `C::Connecting<'!s>: Send` can only be done via the item bound, which then requires `C: '!s` to hold (due to the `where Self: 'a` on the associated type definition). Unfortunately, we don't know that `C: '!s` since we stripped away any relationship between the interior type and the param `C`. This leads to a bogus borrow checker error today!
### Approach
Coroutine interiors are well-formed by virtue of them being borrow-checked, as long as their callers are invoking their parent functions in a well-formed way, then substitutions should also be well-formed. Therefore, in our example above, we should be able to deduce the assumption that `C: '!s` holds from the well-formedness of the interior type `C::Connecting<'!s>`.
This PR introduces the notion of *coroutine assumptions*, which are the outlives assumptions that we can assume hold due to the well-formedness of a coroutine's interior types. These are computed alongside the coroutine types in the `CoroutineWitnessTypes` struct. When we instantiate the binder when proving an auto trait for a coroutine, we instantiate the `CoroutineWitnessTypes` and stash these newly instantiated assumptions in the region storage in the `InferCtxt`. Later on in lexical region resolution or MIR borrowck, we use these registered assumptions to discharge any placeholder outlives obligations that we would otherwise not be able to prove.
### How well does it work?
I've added a ton of tests of different reported situations that users have shared on issues like rust-lang/rust#110338, and an (anecdotally) large number of those examples end up working straight out of the box! Some limitations are described below.
### How badly does it not work?
The behavior today is quite rudimentary, since we currently discharge the placeholder assumptions pretty early in region resolution. This manifests itself as some limitations on the code that we accept.
For example, `tests/ui/async-await/higher-ranked-auto-trait-11.rs` continues to fail. In that test, we must prove that a placeholder is equal to a universal for a param-env candidate to hold when proving an auto trait, e.g. `'!1 = 'a` is required to prove `T: Trait<'!1>` in a param-env that has `T: Trait<'a>`. Unfortunately, at that point in the MIR body, we only know that the placeholder is equal to some body-local existential NLL var `'?2`, which only gets equated to the universal `'a` when being stored into the return local later on in MIR borrowck.
This could be fixed by integrating these assumptions into the type outlives machinery in a more first-class way, and delaying things to the end of MIR typeck when we know the full relationship between existential and universal NLL vars. Doing this integration today is quite difficult today.
`tests/ui/async-await/higher-ranked-auto-trait-11.rs` fails because we don't compute the full transitive outlives relations between placeholders. In that test, we have in our region assumptions that some `'!1 = '!2` and `'!2 = '!3`, but we must prove `'!1 = '!3`.
This can be fixed by computing the set of coroutine outlives assumptions in a more transitive way, or as I mentioned above, integrating these assumptions into the type outlives machinery in a more first-class way, since it's already responsible for the transitive outlives assumptions of universals.
### Moving forward
I'm still quite happy with this implementation, and I'd like to land it for testing. I may work on overhauling both the way we compute these coroutine assumptions and also how we deal with the assumptions during (lexical/nll) region checking. But for now, I'd like to give users a chance to try out this new `-Zhigher-ranked-assumptions` flag to uncover more shortcomings.
[^exist]: Instantiating this binder with infer regions would be incomplete, since we'd be asking for *some* instantiation of the interior types, not proving something for *all* instantiations of the interior types.
Unify `CoroutineWitness` sooner in typeck, and stall coroutine obligations based off of `TypingEnv`
* Stall coroutine obligations based off of `TypingMode` in the old solver.
* Eagerly assign `TyKind::CoroutineWitness` to the witness arg of coroutines during typeck, rather than deferring them to the end of typeck.
r? lcnr
This is part of https://github.com/rust-lang/rust/issues/143017.
