Unsafe kept in help text
Currently when encountering a malformed attribute, the compiler will suggest removing unsafe in the well-formed template even when unsafe is required. This PR preserves whatever unsafe (or lack) exists in the user's code.
r? @jdonszelmann
Remove unsound `target_feature_inline_always` feature
## Summary
- Remove `target_feature_inline_always`
- Update stdarch generators to only use `#[inline]` & regenerate stdarch.
## Why?
Succinctly; the feature relies on LLVMs `AlwaysInlinerPass()` running before LLVMs heuristic based inliner pass. Which is not a basis for sound code.
This has been discussed in [the tracking issue](https://github.com/rust-lang/rust/issues/145574).
If the ordering of the passes were to change, of which they have in the past, it is very possible we could inline functions across callsites with mismatching target features leading to unsound code. Checks proposed in; https://github.com/rust-lang/rust/pull/155426 would only take into account caller -> callee which is not enough to guard against possibly of generating unsound code if the pass ordering were to change.
There doesn't seem to be a way, presently, this this mechanism to provide soundness guarantees nor does it seem like `AlwaysInlinerPass()` is a desired feature of LLVM, which this feature relies on.
r? @RalfJung
Adds an unstable `extern "Swift"` ABI behind the `abi_swift` feature
gate, mapping to LLVM's `swiftcc` calling convention. Cranelift and
GCC backends fall back to the platform default since they have no
equivalent.
docs(unstable-book): Document const generics features
Relevant tracking issues: rust-lang/rust#113521rust-lang/rust#132980rust-lang/rust#76560rust-lang/rust#151972
## What
Adds a high-level overview of 4 unstable features related to const generic exprs.
## Why
While trying to learn about the current state of const generic exprs, I found it a bit too hard due to lack of documentation -- had to read through a bunch of tracking issues & look for PRs/examples in the repo just to understand what the feature is about.
Moreover, given that there is a bunch of features with similarly-looking names, it was even more confusing. For that purpose, I also added cross-referencing across (directly or logically) related features.
As a result, I decided to add some more context to the unstable book, so that new readers have an easier time than I had.
## Caveats
I understand that the features are incomplete/experimental, so the docs are at risk of becoming stale, but the book entrypoint already has [a corresponding warning](https://doc.rust-lang.org/unstable-book/), so I guess it should be fine.
Also, given that I did research myself, the examples provided might be not the best to showcase the feature -- happy to provide better examples, if you have suggestions. The examples provided are what "made the feature make sense" to me as an outsider, so there is a chance that they will be good for other external readers too, though.
LLM use disclosue: an LLM was used for self-review only; research, coming up with examples, and writing is mine. Issues reported by LLM were fixed manually too.
r? @BoxyUwU
Add `const_param_ty_unchecked` gate
Add `const_param_ty_unchecked` internal feature gate to skip `ConstParamTy_` trait enforcement on type. Provides an escape hatch for writing tests and examples that use const generics without needing to ensure all fields implement `ConstParamTy_`.
r? BoxyUwU
Specifically:
- `HashStable` -> `StableHash` (trait)
- `HashStable` -> `StableHash` (derive)
- `HashStable_NoContext` -> `StableHash_NoContext` (derive)
Note: there are some names in `compiler/rustc_macros/src/hash_stable.rs`
that are still to be renamed, e.g. `HashStableMode`.
Part of MCP 983.
`std::hash::Hash` looks like this:
```
pub trait Hash {
fn hash<H>(&self, state: &mut H)
where H: Hasher;
...
}
```
The method is generic.
In contrast, `HashStable` looks like this:
```
pub trait HashStable<Hcx> {
fn hash_stable(&self, hcx: &mut Hcx, hasher: &mut StableHasher);
}
```
and impls look like this (in crates upstream of `rustc_middle`):
```
impl<Hcx: HashStableContext> HashStable<Hcx> for Path {
fn hash_stable(&self, hcx: &mut Hcx, hasher: &mut StableHasher) {
...
}
}
```
or this (in `rustc_middle` and crates downstream of `rustc_middle`):
```
impl<'tcx> HashStable<StableHashingContext<'tcx>> for rustc_feature::Features {
fn hash_stable(&self, hcx: &mut StableHashingContext<'tcx>, hasher: &mut StableHasher) {
...
}
}
```
Differences to `std::hash::Hash`:
- The trait is generic, rather than the method.
- The way impls are written depends their position in the crate graph.
- This explains why we have both `derive(HashStable)` and
`derive(HashStable_Generic)`. The former is for the
downstream-of-`rustc_middle` case, the latter is for the upstream of
`rustc_middle` case.
Why the differences? It all boils down to `HashStable` and
`HashStableContext` being in different crates. But the previous commit
fixed that, which means `HashStable` can be simplified to this, with a
generic method:
```
pub trait HashStable {
fn hash_stable<Hcx: HashStableContext>(&self, hcx: &mut Hcx, hasher: &mut StableHasher);
}
```
and all impls look like this:
```
impl HashStable for Path {
fn hash_stable<Hcx: HashStableContext>(&self, hcx: &mut Hcx, hasher: &mut StableHasher) {
...
}
}
```
Other consequences:
- `derive(HashStable_Generic)` is no longer needed; `derive(HashStable)`
can be used instead.
- In this commit, `derive(HashStable_Generic` is made a synonym of
`derive(HashStable)`. The next commit will remove this synonym,
because it's a change that touches many lines.
- `#[stable_hash_generic]` is no longer needed (for `newtype_index`);
`#[stable_hash]` can be used instead.
- `#[stable_hash_no_context]` was already a synonym of
`#[stable_hash_generic]`, so it's also removed in favour of just
`#[stable_hash]`.
- The difference between `derive(HashStable)` and
`derive(HashStable_NoContext)` now comes down to the difference
between `synstructure::AddBounds::Generics` and
`synstructure::AddBounds::Fields`, which is basically "vanilla derive"
vs "(near) perfect derive".
- I have improved the comments on `HashStableMode` to better
explaining this subtle difference.
- `rustc_middle/src/ich/impls_syntax.rs` is no longer needed; the
relevant impls can be defined in the crate that defines the relevant
type.
- Occurrences of `for<'a> HashStable<StableHashingContext<'a>>` are
replaced with with `HashStable`, hooray.
- The commit adds a `HashStableContext::hashing_controls` method, which
is no big deal. (It's necessary for `AdtDefData::hash_stable`, which
calls `hashing_controls` and used to have an `hcx` that was a
concrete `StableHashingContext` but now has an `hcx` that is just
`Hcx: HashStableContext`.)
Overall this is a big simplification, removing a lot of confusing
complexity in stable hashing traits.
resolve : mark repr_simd as internal
I changed ```repr_simd``` to ```internal``` and changed the position to ```feature-group-start: internal feature gates```.
closerust-lang/rust#154034
Remove AttributeSafety from BUILTIN_ATTRIBUTES
Encodes the expected attribute safety in the attribute parsers, rather than in `BUILTIN_ATTRIBUTES`, with the goal of removing `BUILTIN_ATTRIBUTES` soon.
We can remove the old attribute safety logic already because unparsed attributes, just like the as of yet unparsed lint attributes, need to be safe.
r? @jdonszelmann (or @mejrs if you feel like doing it, since you are in T-compiler now 🎉)
Rollup of 6 pull requests
Successful merges:
- rust-lang/rust#152901 (Introduce a `#[diagnostic::on_unknown]` attribute)
- rust-lang/rust#155078 (Reject dangling attributes in where clauses)
- rust-lang/rust#154449 (Invert dependency between `rustc_errors` and `rustc_abi`.)
- rust-lang/rust#154646 (Add suggestion to `.to_owned()` used on `Cow` when borrowing)
- rust-lang/rust#154993 (compiletest: pass -Zunstable-options for unpretty and no-codegen paths)
- rust-lang/rust#155097 (Make `rustc_attr_parsing::SharedContext::emit_lint` take a `MultiSpan` instead of a `Span`)
CoCo-Japan-pan