`rustc_scalable_vector(N)`
Supercedes rust-lang/rust#118917.
Initial experimental implementation of rust-lang/rfcs#3838. Introduces a `rustc_scalable_vector(N)` attribute that can be applied to types with a single `[$ty]` field (for `u{16,32,64}`, `i{16,32,64}`, `f{32,64}`, `bool`). `rustc_scalable_vector` types are lowered to scalable vectors in the codegen backend.
As with any unstable feature, there will necessarily be follow-ups as we experiment and find cases that we've not considered or still need some logic to handle, but this aims to be a decent baseline to start from.
See rust-lang/rust#145052 for request for a lang experiment.
The `fmt::Debug` impl for `TyAndLayout<'a, Ty>'` requires `fmt::Display`
on the `Ty` parameter. In `ArgAbi`, `TyAndLayout`'s Ty` is instantiated
with a parameter that implements `TyAbiInterface`. `TyAbiInterface`
only required `fmt::Debug` be implemented on `Self`, not `fmt::Display`,
which meant that it wasn't actually possible to debug print `ArgAbi`.
LLVM doesn't handle stores on `<vscale x N x i1>` for `N != 16`, a type
used internally in SVE intrinsics. Spilling to the stack to create
debuginfo will cause errors during instruction selection. These types
that are an internal implementation detail to the intrinsic, so users
should never see them types and won't need any debuginfo.
Co-authored-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
Introduces `BackendRepr::ScalableVector` corresponding to scalable
vector types annotated with `repr(scalable)` which lowers to a scalable
vector type in LLVM.
Co-authored-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
Extend well-formedness checking and HIR analysis to prohibit the use of
scalable vectors in structs, enums, unions, tuples and arrays. LLVM does
not support scalable vectors being members of other types, so these
restrictions are necessary.
Co-authored-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
Extend parsing of `ReprOptions` with `rustc_scalable_vector(N)` which
optionally accepts a single literal integral value - the base multiple of
lanes that are in a scalable vector. Can only be applied to structs.
Co-authored-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
assert impossible branch is impossible
The second half of this boolean or expression should not be possible with the current visitation implementation.
Reasoning:
- Innermost res will always be the first candidate visited.
- the first scopes visited are `derive_helper` candidates, followed by a single step at `derive_helper_compat`: ee447067/compiler/rustc_resolve/src/ident.rs (L180-L192)
- if there are candidates for both kinds the derive_helper candidate will always be innermost
- there can only be one derive_helper_compat candidate
- The first branch handles cases where the first candidate is a `derive_helper_compat`
- if the first candidate is not a `derive_helper_compat` (as enforced by the first branch) and it is not a `derive_helper` (as enforced by the end of the second boolean expression) then then the first candidate and all subsequent candidates must be from later scope types, res cannot possibly be a `derive_helper_compat`
r? ``@petrochenkov``
Update books
## rust-lang/nomicon
1 commits in 9fe8fa599ad228dda74f240cc32b54bc5c1aa3e6..5b3a9d084cbc64e54da87e3eec7c7faae0e48ba9
2025-12-12 12:24:05 UTC to 2025-12-12 12:24:05 UTC
- Update method lookup link in dot-operator.md (rust-lang/nomicon#513)
## rust-lang/reference
4 commits in 50c5de90487b68d429a30cc9466dc8f5b410128f..ec78de0ffe2f8344bd0e222b17ac7a7d32dc7a26
2025-12-15 16:17:43 UTC to 2025-12-15 16:15:06 UTC
- tokens: clarify in escape tables that digits are hex (rust-lang/reference#2105)
- tokens: remove misplaced ".token." within a word (rust-lang/reference#2106)
- macros-by-example: add space in `macro.decl.repetition.fragment` example (rust-lang/reference#2107)
- Fix restrictions of or-patterns (rust-lang/reference#2108)
document that mpmc channels deliver an item to (at most) one receiver
Tiny documentation change related to mpmc (tracking issue rust-lang/rust#126840).
This PR is meant to supersede rust-lang/rust#140158 due to it's inactivity. It is essentially the same addition structured a little differently.
Metadata loader cleanups
Couple of cleanups I found while working on https://github.com/rust-lang/rust/pull/149273
This renames some fields and enum variants to clarify what they are used for, moves a check to another method and slightly simplifies the way profiler_builtins is linked.
Simplify how inline asm handles `MaybeUninit`
This is just better, but this is also allows it to handle changes from https://github.com/rust-lang/rust/pull/149614 (i.e. `ManuallyDrop` containing `MaybeDangle`).
Provide an extended framework for type visit, for use in rust-analyzer
rust-analyzer needs to be able to visit types when treating not only `Ty`, `Const`, `Region` and `Predicate` specifically, but *all* rust-analyzer-made types specifically (excluding e.g. `TraitRef`, that is declared in rustc_type_ir). This is needed to implement garbage collection.
To support this, we introduce a second, rust-analyzer-only visit trait, named, without much thought, `CustomizableTypeVisitable`. It's simpler than `TypeVisitable` (for example, it does not have a trait for the visitor, and does not support early-returning) because this is what rust-analyzer needs, but its most distinguished feature is that the visitor is a generic of the *trait* instead of the *method*. This way, specific types can treat specific visitor types specifically and call their methods.
In rustc_type_ir we implement it for a bunch of basic types, and using a derive macro for the rest. The macro and trait are completely disabled when compiling for rustc (`feature = "nightly"`), so not even a compile time penalty will be paid.
r? types
This is a replacement to other efforts to support non-`Copy` type in the solver, replacing them with a GC in r-a, as decided by ``@rust-lang/rust-analyzer.`` The code is tiny in comparison, and I believe T-types will have no problem maintaining it, which mostly means adding the derive on new things when they are added and things break on the r-a side.
Add new Tier-3 target: riscv64im-unknown-none-elf
This PR proposes to add riscv64im-unknown-none-elf, a subset of the already supported riscv64imac-unknown-none-elf.
The motivation behind this PR is that we want to standardize (most) zkVMs on riscv64im-none and riscv64ima-none. Having different variants of riscv extensions, also seems to be within expectation, atleast with respects to riscv32.
Note: This does not mean that we will be able to remove [riscv32im-risc0-zkvm-elf](https://doc.rust-lang.org/rustc/platform-support/riscv32im-risc0-zkvm-elf.html) -- I am not aware of all of the dependents for this
**Tier-3 Policy**
> 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.)
I assigned Rust Embedded Working Group, since they are already maintaining riscv64IMAC, though I am happy to assign myself.
> 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.
It follows the naming convention of the other bare metal riscv targets
> 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.
This has the same requirements as riscv{32, 64}imac
> 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.
> 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 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.
> 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.
> 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.
> Tier 3 targets must be able to produce assembly using at least one of rustc's supported backends from any host target. (Having support in a fork of the backend is not sufficient, it must be upstream.)
Acknowledging the above.
Warn on codegen attributes on required trait methods
This PR turns applying the following attributes on required trait methods (that is, trait methods **without** a default implementation) into a FCW:
- `#[cold]`
- `#[link_section]`
- `#[linkage]` (unstable)
- `#[rustc_allow_const_fn_unstable]` (internal attribute)
These attributes already had no effect when applied to a required trait method, this PR only adds a warning.
Furthermore, it adds a comment in the code that the following codegen attributes are *inherited* when applied to a required trait method:
- `#[track_caller]`
- `#[align]` (unstable)
````@rustbot```` labels +I-lang-nominated
````@rust-lang/lang````
Two questions for the lang team:
- Is adding this warning ok?
- Does the current behaviour of these attributes align with that you would expect them to be?
Fixes https://github.com/rust-lang/rust/issues/147432
rust-analyzer needs to be able to visit types when treating not only `Ty`, `Const`, `Region` and `Predicate` specifically, but *all* rust-analyzer-made types specifically (excluding e.g. `TraitRef`, that is declared in rustc_type_ir). This is needed to implement garbage collection.
To support this, we introduce a second, rust-analyzer-only visit trait, named `GenericTypeVisitable`. It's simpler than `TypeVisitable` (for example, it does not have a trait for the visitor, and does not support early-returning) because this is what rust-analyzer needs, but its most distinguished feature is that the visitor is a generic of the *trait* instead of the *method*. This way, specific types can treat specific visitor types specifically and call their methods.
In rustc_type_ir we implement it for a bunch of basic types, and using a derive macro for the rest. The macro and trait are completely disabled when compiling for rustc (`feature = "nightly"`), so not even a compile time penalty will be paid.
std: small `sys` refactor
Part of rust-lang/rust#117276
The large number of files changed just results from the need to update a lot of imports. Actually this PR only:
* combines the two definitions of `RawOsError` in `sys::pal` into one in `sys::io`
* moves `FULL_BACKTRACE_DEFAULT` from `sys::pal` to `sys::backtrace`
* moves the `FromInner`/`IntoInner`/... traits into `sys` (in preparation for removing `sys_common` entirely)
