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.
(cherry picked from commit 69b71e4410)
Key changes include:
- Removal of the word "syntax" from the lint message. More accurately,
it could have been something like "syntax group" or "syntax
category", but avoiding it completely is easier.
- The primary lint message now reflects exactly which mismatch is
occurring, instead of trying to be general. A new `help` line is
general across the mismatch kinds.
- Suggestions have been reduced to be more minimal, no longer also
changing non-idiomatic but unrelated aspects.
- Suggestion text no longer mentions changes when those changes don't
occur in that specific suggestion.
(cherry picked from commit 5530744318)
As a temporary measure while a proper fix for
`tests/ui/sized-hierarchy/incomplete-inference-issue-143992.rs`
is implemented, make `MetaSized` obligations always hold. In effect,
temporarily reverting the `sized_hierarchy` feature. This is a small
change that can be backported.
(cherry picked from commit 8d64937dc2)
Several UI tests have a `normalize-stderr` for "you are using x.y.z"
rustc versions, and that regex is flexible enough for suffixes like
"-nightly" and "-dev", but not for "-beta.N". We can just add '.' to
that trailing pattern to include this.
(cherry picked from commit 8469966710)
Document subdirectories of UI tests with README files
Part of rust-lang/rust#133895 and the [2025 Google Summer of Code](https://blog.rust-lang.org/2025/05/08/gsoc-2025-selected-projects/) associated project.
When adding a new UI test, one is faced with hundreds of subdirectories in `tests/ui` reflecting various categories. Knowing where to put the new test is not trivial, as many of the categories have slightly misleading names. For example, `moves` does not only refer to the `move` keyword but to functions taking ownership in general, whereas `allocator` does not refer to allocation in general but rather to the very specific `allocator_api` and `global_allocator` features.
Many contributors will therefore place their test at the top level of ̀`tests/ui` where it will be mixed with hundreds of unrelated tests.
This PR is a tentative move towards more clearly defined tag/categories, with a SUMMARY.md file documenting the true purpose of each subdirectory, placed inside `tests/ui`.
r? ``@jieyouxu``
Add DesugaringKind::FormatLiteral
Implements `DesugaringKind::FormatLiteral` to mark the FormatArgs desugaring of format literals. The main use for this is to stop yapping about about formatting parameters if we're not anywhere near a format literal. The other use case is to fix suggestions such as https://github.com/rust-lang/rust/issues/141350. It might also be useful for new or existing diagnostics that check whether they're in a format-like macro.
cc `@xizheyin` `@fmease`
Merge unboxed trait object error suggestion into regular dyn incompat error
Another hir-walker removed from the well-formed queries. This error was always a duplicate of another, but it was able to provide more information because it could invoke `is_dyn_compatible` without worrying about cycle errors. That's also the reason we can't put the error directly into hir_ty_lowering when lowering a `dyn Trait` within an associated item signature. So instead I packed it into the error handling of wf obligation checking.
All HIR attributes are outer
Fixes https://github.com/rust-lang/rust/issues/142649. Closes https://github.com/rust-lang/rust/pull/142759.
All HIR attributes, including parsed and not yet parsed, will now be rendered as outer attributes by `rustc_hir_pretty`. The original style of the corresponding AST attribute(s) is not relevant for pretty printing, only for diagnostics.
r? ````@jdonszelmann````
Only traverse reachable blocks in JumpThreading.
Fixes https://github.com/rust-lang/rust/issues/131451
We only compute loop headers for reachable blocks. We shouldn't try to perform an opt on unreachable blocks anyway.
Improve diagnostics for `concat_bytes!` with C string literals
Use the same error as other invalid types for `concat_bytes!`, rather
than using `ConcatCStrLit` from `concat!`. Also add more information
with a note about why this doesn't work, and a suggestion to use a
null-terminated byte string instead.
Add diagnostic items for Clippy
Clippy still uses some paths to access items from the standard library. Adding the missing diagnostic items allows removing the last remaining paths.
Closesrust-lang/rust-clippy#5393
error on calls to ABIs that cannot be called
We recently added `extern "custom"`, which cannot be called using a rust call expression. But there are more ABIs that can't be called in that way, because the call does not semantically make sense.
More details are in https://github.com/rust-lang/rust/issues/140566#issuecomment-2846205457
r? `@workingjubilee`
try-job: x86_64-gnu-llvm-19-3
Marks ADT live if it appears in pattern
Marks ADT live if it appears in pattern, it implies the construction of the ADT.
1. Then we can detect unused private ADTs impl `Default`, without special logics for `Default` and other std traits.
2. We can also remove `rustc_trivial_field_reads` on `Default`, and the logic in `should_ignore_item` (introduced by rust-lang/rust#126302).
Fixesrust-lang/rust#120770
Extracted from rust-lang/rust#128637.
r? `@petrochenkov`
correct template for `#[align]` attribute
Tracking issue: https://github.com/rust-lang/rust/issues/82232
related: https://github.com/rust-lang/rust/pull/142507
I didn't fully understand what `template!` did, clearly. An empty `#[align]` attribute was still rejected later, but without this change it does get suggested in certain cases.
I've also updated some outdated references to `#[repr(align)]` on functions.
r? ``@jdonszelmann``
Alternative candidates for a trait implementation are not printed when
the trait has a diagnostic name, to avoid printing alternatives for
common stdlib traits such as `Copy` or `Debug`. However, this affects
all traits for which a diagnostic item is added.
Here, the list of alternatives candidates for `Step` does not seem
useful, and `Step` is unstable, so this will not be missed.
Extract some shared code from codegen backend target feature handling
There's a bunch of code duplication between the GCC and LLVM backends in target feature handling. This moves that into new shared helper functions in `rustc_codegen_ssa`.
The first two commits should be purely refactoring. I am fairly sure the LLVM-side behavior stays the same; if the GCC side deliberately diverges from this then I may have missed that. I did account for one divergence, which I do not know is deliberate or not: GCC does not seem to use the `-Ctarget-feature` flag to populate `cfg(target_feature)`. That seems odd, since the `-Ctarget-feature` flag is used to populate the return value of `global_gcc_features` which controls the target features actually used by GCC. ``@GuillaumeGomez`` ``@antoyo`` is there a reason `target_config` ignores `-Ctarget-feature` but `global_gcc_features` does not? The second commit also cleans up a bunch of unneeded complexity added in https://github.com/rust-lang/rust/pull/135927.
The third commit extracts some shared logic out of the functions that populate `cfg(target_feature)` and the backend target feature set, respectively. This one actually has some slight functional changes:
- Before, with `-Ctarget-feature=-feat`, if there is some other feature `x` that implies `feat` we would *not* add `-x` to the backend target feature set. Now, we do. This fixesrust-lang/rust#134792.
- The logic that removes `x` from `cfg(target_feature)` in this case also changed a bit, avoiding a large number of calls to the (uncached) `sess.target.implied_target_features` (if there were a large number of positive features listed before a negative feature) but instead constructing a full inverse implication map when encountering the first negative feature. Ideally this would be done with queries but the backend target feature logic runs before `tcx` so we can't use that...
- Previously, if feature "a" implied "b" and "b" was unstable, then using `-Ctarget-feature=+a` would also emit a warning about `b`. I had to remove this since when accounting for negative implications, this emits a ton of warnings in a bunch of existing tests... I assume this was unintentional anyway.
The fourth commit increases consistency of the GCC backend with the LLVM backend.
The last commit does some further cleanup:
- Get rid of RUSTC_SPECIAL_FEATURES. It was only needed for s390x "backchain", but since LLVM 19 that is always a regular target feature so we don't need this hack any more. The hack also has various unintended side-effects so we don't want to keep it. Fixes https://github.com/rust-lang/rust/issues/142412.
- Move RUSTC_SPECIFIC_FEATURES handling into the shared parse_rust_feature_flag helper so all consumers of `-Ctarget-feature` that only care about actual target features (and not "crt-static") have it. Previously, we actually set `cfg(target_feature = "crt-static")` twice: once in the backend target feature logic, and once specifically for that one feature. IIUC, some targets are meant to ignore `-Ctarget-feature=+crt-static`, it seems like before this PR that flag still incorrectly enabled `cfg(target_feature = "crt-static")` (but I didn't test this).
- Move fixed_x18 handling together with retpoline handling.
- Forbid setting fixed_x18 as a regular target feature, even unstably. It must be set via the `-Z` flag.
``@bjorn3`` I did not touch the cranelift backend here, since AFAIK it doesn't really support target features. But if you ever do, please use the new helpers. :)
Cc ``@workingjubilee``
rewrite `optimize` attribute to use new attribute parsing infrastructure
r? ```@oli-obk```
I'm afraid we'll get quite a few of these PRs in the future. If we get a lot of trivial changes I'll start merging multiple into one PR. They should be easy to review :)
Waiting on #138165 first
`{{root}}` is supposed to be an internal-only name but it shows up in
the output.
(I'm working towards a more general fix -- a universal "joiner" function
that can be used all over the place -- but I'm not there yet, so let's
fix this one in-place for now.)
Use the same error as other invalid types for `concat_bytes!`, rather
than using `ConcatCStrLit` from `concat!`. Also add more information
with a note about why this doesn't work, and a suggestion to use a
null-terminated byte string instead.
