Rework target checking for built-in attributes
This is a refactoring of target checking for built-in attributes.
This PR has the following goals:
- Only refactor the 80% of the attributes that are simple to target check. More complicated ones like `#[repr]` will be in a future PR. Tho I have written the code in such a way that this will be possible to add in the future.
- No breaking changes.
- This part of the codebase is not very well tested though, we can do a crater run if we want to be sure.
- I've spotted quite a few weird situations (like I don't think an impl block should be deprecated?). We can propose fixing these to in a future PR
Fixes https://github.com/rust-lang/rust/issues/143780
Fixes https://github.com/rust-lang/rust/issues/138510
I've split it in commits and left a description on some of the commits to help review.
r? `@jdonszelmann`
Stabilize `sse4a` and `tbm` target features
This PR stabilizes the feature flag `sse4a_target_feature` and `tbm_target_feature` (tracking issue rust-lang/rust#44839).
# Public API
The 2 `x86` target features `sse4a` and `tbm`
Also, these were added in LLVM2.6 and LLVM3.4-rc1, respectively, and as the minimum LLVM required for rustc is LLVM19, we are safe in that front too!
As all of the required tasks have been done (adding the target features to rustc, implementing their runtime detection in std_detect and implementing the associated intrinsics in core_arch), these target features can be stabilized now. The intrinsics were stabilized *long* ago, in 1.27.0
Reference PR:
- https://github.com/rust-lang/reference/pull/1949
cc `@rust-lang/lang`
`@rustbot` label I-lang-nominated
r? lang
Currently they are skipped, which is a bit weird, and it sometimes
causes malformed output like `Foo<>` and `dyn Bar<, A = u32>`.
Most regions are erased by the time `type_name` does its work. So all
regions are now printed as `'_` in non-optional places. Not perfect, but
better than the status quo.
`c_name` is updated to trim lifetimes from MIR pass names, so that the
`PASS_NAMES` sanity check still works. It is also renamed as
`simplify_pass_type_name` and made non-const, because it doesn't need
to be const and the non-const implementation is much shorter.
The commit also renames `should_print_region` as
`should_print_optional_region`, which makes it clearer that it only
applies to some regions.
Fixes#145168.
Suppress wrapper suggestion when expected and actual ty are the same adt and the variant is unresolved
Fixesrust-lang/rust#145294
I initially tried the desired suggestion in this issue, but since that suggestion occurs in the expected type, it is inappropriate to suggest for expected expressions (see other suggest methods in the same file). I believe that suppressing the incorrect suggestion is the more appropriate choice here.
I opted for a slightly more general approach: when the expected type and actual type are the same ADT (e.g., both are Result in this example), we assume that code tend to compare the internal generic parameters(i.e. `Option<&str>` vs `Option<String>`, instead of `E = _` vs `Result<Option<String>>>`). When `E` is an unresolved infer type in the expected type (`_` in this example), we should not wrapp the actual type.
Two commits show the difference.
r? compiler
rustdoc: Allow multiple references to a single footnote
Multiple references to a single footnote is a part of GitHub Flavored Markdown syntax (although not explicitly documented as well as regular footnotes, it is implemented in GitHub's fork of CommonMark) and not prohibited by rustdoc.
cf. <587a12bb54/test/extensions.txt (L762-L780)>
However, using it makes multiple `sup` elements with the same `id` attribute, which is invalid per the HTML specification.
Still, not only this is a valid GitHub Flavored Markdown syntax, this is helpful on certain cases and actually tested (accidentally) in `tests/rustdoc/footnote-reference-in-footnote-def.rs`.
This commit keeps track of the number of references per footnote and gives unique ID to each reference.
It also emits *all* back links from a footnote to its references as "↩" (return symbol) plus a numeric list in superscript.
As a known limitation, it assumes that all references to a footnote are rendered (this is not always true if a dangling footnote has one or more references but considered a reasonable compromise).
Also note that, this commit is designed so that no HTML changes will occur unless multiple references to a single footnote is actually used.
Remove one FIXME, addressing it does not reduce the hacky-ness much, and the logic is going to be removed anyway together with the `legacy_derive_helpers` deprecation lint.
Multiple references to a single footnote is a part of GitHub Flavored
Markdown syntax (although not explicitly documented as well as regular
footnotes, it is implemented in GitHub's fork of CommonMark) and not
prohibited by rustdoc.
cf. <587a12bb54/test/extensions.txt (L762-L780)>
However, using it makes multiple "sup" elements with the same "id"
attribute, which is invalid per the HTML specification.
Still, not only this is a valid GitHub Flavored Markdown syntax, this is
helpful on certain cases and actually tested (accidentally) in
tests/rustdoc/footnote-reference-in-footnote-def.rs.
This commit keeps track of the number of references per footnote and gives
unique ID to each reference. It also emits *all* back links from a footnote
to its references as "↩" (return symbol) plus a numeric list in superscript.
As a known limitation, it assumes that all references to a footnote are
rendered (this is not always true if a dangling footnote has one or more
references but considered a reasonable compromise).
Also note that, this commit is designed so that no HTML changes will occur
unless multiple references to a single footnote is actually used.
resolve: Split extern prelude into two scopes
One scope for `extern crate` items and another for `--extern` options, with the former shadowing the latter.
If in a single scope some things can overwrite other things, especially with ad hoc restrictions like `MacroExpandedExternCrateCannotShadowExternArguments`, then it's not really a single scope.
So this PR splits `Scope::ExternPrelude` into two cleaner scopes.
This is similar to how https://github.com/rust-lang/rust/pull/144131 splits module scope into two scopes for globs and non-globs, but simpler.
Handle macros with multiple kinds, and improve errors
(I recommend reviewing this commit-by-commit.)
Switch to a bitflags `MacroKinds` to support macros with more than one kind
Review everything that uses `MacroKind`, and switch anything that could refer to more than one kind to use `MacroKinds`.
Add a new `SyntaxExtensionKind::MacroRules` for `macro_rules!` macros, using the concrete `MacroRulesMacroExpander` type, and have it track which kinds it can handle. Eliminate the separate optional `attr_ext`, now that a `SyntaxExtension` can handle multiple macro kinds.
This also avoids the need to downcast when calling methods on `MacroRulesMacroExpander`, such as `get_unused_rule`.
Integrate macro kind checking into name resolution's `sub_namespace_match`, so that we only find a macro if it's the right type, and eliminate the special-case hack for attributes.
This allows detecting and report macro kind mismatches early, and more precisely, improving various error messages. In particular, this eliminates the case in `failed_to_match_macro` to check for a function-like invocation of a macro with no function-like rules.
Instead, macro kind mismatches now result in an unresolved macro, and we detect this case in `unresolved_macro_suggestions`, which now carefully distinguishes between a kind mismatch and other errors.
This also handles cases of forward-referenced attributes and cyclic attributes.
----
In this PR, I've minimally fixed up `rustdoc` so that it compiles and passes tests. This is just the minimal necessary fixes to handle the switch to `MacroKinds`, and it only works for macros that don't actually have multiple kinds. This will panic (with a `todo!`) if it encounters a macro with multiple kinds.
rustdoc needs further fixes to handle macros with multiple kinds, and to handle attributes and derive macros that aren't proc macros. I'd appreciate some help from a rustdoc expert on that.
----
r? ````````@petrochenkov````````
Add aarch64_be-unknown-none-softfloat target
This adds a new target for bare-metal big endian ARM64 without FPU. We want to use this in [the Hermit unikernel](https://github.com/hermit-os/kernel) because big endian ARM64 is the most accessible big endian architecture for us and it can be supported with our existing aarch64 code. I have compiled our kernel and bootloader with this target and they work as expected in QEMU.
Regarding the [tier 3 target policy](https://doc.rust-lang.org/rustc/target-tier-policy.html#tier-3-target-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.)
The maintainer(s) (currently just me) are listed in the markdown document that documents the target.
> - 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.
> - Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.
> - If possible, use only letters, numbers, dashes and underscores for the name. Periods (.) are known to cause issues in Cargo.
The target name is consistent with the existing `aarch64-unknown-none-softfloat` target and the existing big endian aarch64 targets like `aarch64_be-unknown-linux-gnu`.
> - 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.
> - The target must not introduce license incompatibilities.
> - Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0).
> - The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.
> - Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.
> - "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.
There are no licensing issues and any toolchain that can compile for `aarch64-unknown-none-softfloat` can also compile for `aarch64_be-unknown-none-softfloat` (well, at least GCC and LLVM). No proprietary components are required.
> - 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.
> - This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements.
Ack.
> - 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.
This target does not implement std and is equivalent to `aarch64-unknown-none-softfloat` in all these regards.
> - 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.
Ack, that is part of the markdown document.
> - 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.
> - Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.
Ack.
> - 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.
> - In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.
This doesn't break any existing targets.
> - 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.)
The LLVM backend works.
> - If a tier 3 target stops meeting these requirements, or the target maintainers no longer have interest or time, or the target shows no signs of activity and has not built for some time, or removing the target would improve the quality of the Rust codebase, we may post a PR to remove it; any such PR will be CCed to the target maintainers (and potentially other people who have previously worked on the target), to check potential interest in improving the situation.
Ack.
aarch64: Make `outline-atomics` a known target feature
This is a feature used by LLVM that is enabled for our `aarch64-linux` targets, which we would like to configure on in `std`. Thus, mark `outline-atomics` a known feature. It is left unstable for now.
set
* Enforce the `-Zregparm=N` flag by setting the NumRegisterParameters
LLVM module flag * Add assembly tests verifying that the parameters are
passed in registers for reparm values 1, 2, and 3, for both LLVM
intrinsics and non-builtin functions * Add c_void type to minicore
Fix parallel rustc not being reproducible due to unstable sorts of items
Currently, A tuple `(DefId, SymbolName)` is used to determine the order of items in the final binary. However `DefId` is expected as non-deterministic, which leads to some not reproducible issues under parallel compilation. (See https://github.com/rust-lang/rust/issues/140425#issuecomment-3111802148)
Theoretically, we don't need the sorting because the order of these items is already deterministic.
However, codegen tests reply on the same order of items between in binary and source.
So here we added a new option `codegen-source-order` to indicate whether sorting based on the order in source. For codegen tests, items are sorted according to the order in the source code, whereas in the normal path, no sorting is performed.
Specially, for codegen tests, in preparation for parallel compilation potentially being enabled by default in the future, we use `Span` replacing `DefId` to make the order deterministic.
This PR is purposed to fixrust-lang/rust#140425, but seemly works on rust-lang/rust#140413 too.
This behavior hasn't added into any test until we have a test suit for the parallel frontend. (See https://github.com/rust-lang/rust/pull/143953)
Related discussion: [Zulip](https://rust-lang.zulipchat.com/#narrow/channel/187679-t-compiler.2Fparallel-rustc/topic/Async.20closures.20not.20reproducible.28.23140425.29) https://github.com/rust-lang/rust/pull/144576
Update rust-lang/rust#113349
r? `@oli-obk`
cc `@lqd` `@cramertj` `@matthiaskrgr` `@Zoxc` `@SparrowLii` `@bjorn3` `@cjgillot` `@joshtriplett`
Set dead_on_return attribute for indirect arguments
Set the dead_on_return attribute (added in LLVM 21) for arguments that are passed indirectly, but not byval.
This indicates that the value of the argument on return does not matter, enabling additional dead store elimination.
From LangRef:
> This attribute indicates that the memory pointed to by the argument is dead upon function return, both upon normal return and if the calls unwinds, meaning that the caller will not depend on its contents. Stores that would be observable either on the return path or on the unwind path may be elided.
>
> Specifically, the behavior is as-if any memory written through the pointer during the execution of the function is overwritten with a poison value upon function return. The caller may access the memory, but any load not preceded by a store will return poison.
>
> This attribute does not imply aliasing properties. For pointer arguments that do not alias other memory locations, noalias attribute may be used in conjunction. Conversely, this attribute always implies dead_on_unwind.
>
> This attribute cannot be applied to return values.
This fixes parts of https://github.com/rust-lang/rust/issues/96497.
