Most Rust freestanding/bare-metal targets use just `-unknown-none` here,
including aarch64-unknown-none, mipsel-unknown-none, and the BPF
targets. The *only* target using `-unknown-none-elf` is RISC-V.
The underlying toolchain doesn't care; LLVM accepts both `x86_64-unknown-none`
and `x86_64-unknown-none-elf`.
In addition, there's a long history of embedded x86 targets with varying
definitions for the `elf` suffix; on some of those embedded targets,
`elf` implied the inclusion of a C library based on newlib or similar.
Using `x86_64-unknown-none` avoids any potential ambiguity there.
(Work on this target sponsored by Profian.)
SOLID[1] is an embedded development platform provided by Kyoto
Microcomputer Co., Ltd. This commit introduces a basic Tier 3 support
for SOLID.
# New Targets
The following targets are added:
- `aarch64-kmc-solid_asp3`
- `armv7a-kmc-solid_asp3-eabi`
- `armv7a-kmc-solid_asp3-eabihf`
SOLID's target software system can be divided into two parts: an
RTOS kernel, which is responsible for threading and synchronization,
and Core Services, which provides filesystems, networking, and other
things. The RTOS kernel is a μITRON4.0[2][3]-derived kernel based on
the open-source TOPPERS RTOS kernels[4]. For uniprocessor systems
(more precisely, systems where only one processor core is allocated for
SOLID), this will be the TOPPERS/ASP3 kernel. As μITRON is
traditionally only specified at the source-code level, the ABI is
unique to each implementation, which is why `asp3` is included in the
target names.
More targets could be added later, as we support other base kernels
(there are at least three at the point of writing) and are interested
in supporting other processor architectures in the future.
# C Compiler
Although SOLID provides its own supported C/C++ build toolchain, GNU Arm
Embedded Toolchain seems to work for the purpose of building Rust.
# Unresolved Questions
A μITRON4 kernel can support `Thread::unpark` natively, but it's not
used by this commit's implementation because the underlying kernel
feature is also used to implement `Condvar`, and it's unclear whether
`std` should guarantee that parking tokens are not clobbered by other
synchronization primitives.
# Unsupported or Unimplemented Features
Most features are implemented. The following features are not
implemented due to the lack of native support:
- `fs::File::{file_attr, truncate, duplicate, set_permissions}`
- `fs::{symlink, link, canonicalize}`
- Process creation
- Command-line arguments
Backtrace generation is not really a good fit for embedded targets, so
it's intentionally left unimplemented. Unwinding is functional, however.
## Dynamic Linking
Dynamic linking is not supported. The target platform supports dynamic
linking, but enabling this in Rust causes several problems.
- The linker invocation used to build the shared object of `std` is
too long for the platform-provided linker to handle.
- A linker script with specific requirements is required for the
compiled shared object to be actually loadable.
As such, we decided to disable dynamic linking for now. Regardless, the
users can try to create shared objects by manually invoking the linker.
## Executable
Building an executable is not supported as the notion of "executable
files" isn't well-defined for these targets.
[1] https://solid.kmckk.com/SOLID/
[2] http://ertl.jp/ITRON/SPEC/mitron4-e.html
[3] https://en.wikipedia.org/wiki/ITRON_project
[4] https://toppers.jp/
Add initial support for m68k
This patch series adds initial support for m68k making use of the new M68k
backend introduced with LLVM-13. Additional changes will be needed to be
able to actually use the backend for this target.
Enum should prefer discriminant zero for niche
Given an enum with unassigned zero-discriminant, rust should prefer it for niche selection.
Zero as discriminant for `Option<Enum>` makes it possible for LLVM to optimize resulting asm.
- Eliminate branch when expected value coincides.
- Use smaller instruction `test eax, eax` instead of `cmp eax, ?`
- Possible interaction with zeroed memory?
Example:
```rust
pub enum Size {
One = 1,
Two = 2,
Three = 3,
}
pub fn handle(x: Option<Size>) -> u8 {
match x {
None => {0}
Some(size) => {size as u8}
}
}
```
In this case discriminant zero is available as a niche.
Above example on nightly:
```asm
mov eax, edi
cmp al, 4
jne .LBB0_2
xor eax, eax
.LBB0_2:
ret
```
PR:
```asm
mov eax, edi
ret
```
I created this PR because I had a performance regression when I tried to use an enum to represent legal grapheme byte-length for utf8.
Using an enum instead of `NonZeroU8` [here](d683304f5d/src/internal/decoder_incomplete.rs (L90))
resulted in a performance regression of about 5%.
I consider this to be a somewhat realistic benchmark.
Thanks to `@ogoffart` for pointing me in the right direction!
Edit: Updated description
ARMv6K Nintendo 3DS Tier 3 target added
Addition of the target specifications to build .elf files for Nintendo 3DS (ARMv6K, Horizon). Requires devkitARM 3DS toolkit for system libraries and arm-none-eabi-gcc linker.
Move *_max methods back to util
change to inline instead of inline(always)
Remove valid_range_exclusive from scalar
Use WrappingRange instead
implement always_valid_for in a safer way
Fix accidental edit
Provide `layout_of` automatically (given tcx + param_env + error handling).
After #88337, there's no longer any uses of `LayoutOf` within `rustc_target` itself, so I realized I could move the trait to `rustc_middle::ty::layout` and redesign it a bit.
This is similar to #88338 (and supersedes it), but at no ergonomic loss, since there's no funky `C: LayoutOf<Ty = Ty>` -> `Ty: TyAbiInterface<C>` generic `impl` chain, and each `LayoutOf` still corresponds to one `impl` (of `LayoutOfHelpers`) for the specific context.
After this PR, this is what's needed to get `trait LayoutOf` (with the `layout_of` method) implemented on some context type:
* `TyCtxt`, via `HasTyCtxt`
* `ParamEnv`, via `HasParamEnv`
* a way to transform `LayoutError`s into the desired error type
* an error type of `!` can be paired with having `cx.layout_of(...)` return `TyAndLayout` *without* `Result<...>` around it, such as used by codegen
* this is done through a new `LayoutOfHelpers` trait (and so is specifying the type of `cx.layout_of(...)`)
When going through this path (and not bypassing it with a manual `impl` of `LayoutOf`), the end result is that only the error case can be customized, the query itself and the success paths are guaranteed to be uniform.
(**EDIT**: just noticed that because of the supertrait relationship, you cannot actually implement `LayoutOf` yourself, the blanket `impl` fully covers all possible context types that could ever implement it)
Part of the motivation for this shape of API is that I've been working on querifying `FnAbi::of_*`, and what I want/need to introduce for that looks a lot like the setup in this PR - in particular, it's harder to express the `FnAbi` methods in `rustc_target`, since they're much more tied to `rustc` concepts.
r? `@nagisa` cc `@oli-obk` `@bjorn3`
rustc_target: `TyAndLayout::field` should never error.
This refactor (making `TyAndLayout::field` return `TyAndLayout` without any `Result` around it) is based on a simple observation, regarding `TyAndLayout::field`:
If `cx.layout_of(ty)` succeeds (for some `cx` and `ty`), then `.field(cx, i)` on the resulting `TyAndLayout` should *always* succeed in computing `cx.layout_of(field_ty)` (where `field_ty` is the type of the `i`th field of `ty`).
The reason for this is that no matter which field is chosen, `cx.layout_of(field_ty)` *will have already been computed*, as part of computing `cx.layout_of(ty)`, as we cannot determine the layout of *any* type without considering the layouts of *all* of its fields.
And so it should be fine to turn any errors into ICEs, since they likely indicate a `cx` mismatch, or some other edge case that is due to a compiler bug (as opposed to ever being an user-facing error).
<hr/>
Each commit should probably be reviewed separately, though note that there's some `where` clauses (in `rustc_target::abi::call::*`) that change in most commits.
cc `@nagisa` `@oli-obk`
Make `-Z gcc-ld=lld` work for Apple targets
`-Z gcc-ld=lld` was introduced in #85961. It does not work on Macos because lld needs be either named `ld64` or passed `-flavor darwin` as the first two arguments in order to select the Mach-O flavor. Rust invokes cc (=clang) on Macos for linking which calls `ld` as linker binary and not `ld64`, so just creating an `ld64` binary and modifying the search path with `-B` does not work.
In order to solve this patch does:
* Set the `lld_flavor` for all Apple-derived targets to `LldFlavor::Ld64`. As far as I can see this actually works towards fixing `-Xlinker=rust-lld` as all those targets use the Mach-O object format.
* Copy/hardlink rust-lld to the gcc-ld subdirectory as ld64 next to ld.
* If `-Z gcc-ld=lld` is used and the target lld flavor is Ld64 add `-fuse-ld=/path/to/ld64` to the linker invocation.
Fixes#86945.
S390x inline asm
This adds register definitions and constraint codes for the s390x general and floating point registers necessary for fixing #85931; as well as a few tests.
Further testing is needed, but I am a little unsure of what specific tests should be added to `src/test/assembly/asm/s390x.rs` to address this.
Morph `layout_raw` query into `layout_of`.
Before this PR, `LayoutCx::layout_of` wrapped the `layout_raw` query, to:
* normalize the type, before attempting to compute the layout
* pass the layout to `record_layout_for_printing`, for `-Zprint-type-sizes`
Moving those two responsibilities into the query may reduce overhead (due to cached calls skipping those steps), but I want to do a perf run to know.
One of the changes I had to make was changing the return type of the query, to be able to both get out the type produced by normalizing inside the query *and* to match the signature of the old `TyCtxt::layout_of`. This change may be worse, perf-wise, so that's another reason I want to check.
r? `@nagisa` cc `@oli-obk`
Use custom wrap-around type instead of RangeInclusive
Two reasons:
1. More memory is allocated than necessary for `valid_range` in `Scalar`. The range is not used as an iterator and `exhausted` is never used.
2. `contains`, `count` etc. methods in `RangeInclusive` are doing very unhelpful(and dangerous!) things when used as a wrap-around range. - In general this PR wants to limit potentially confusing methods, that have a low probability of working.
Doing a local perf run, every metric shows improvement except for instructions.
Max-rss seem to have a very consistent improvement.
Sorry - newbie here, probably doing something wrong.
Allow specifying an deployment target version for all iOS llvm targets
Closes: https://github.com/rust-lang/rust/issues/79408
This pull requests adds the same procedure to define the iOS-version for the LLVM-target as was used for the simulator target and the desktop target.
This then closes the original problem mentioned in the above issue. The problem with incompatible bitcode remains, but is probably not easy fixable.
I realised that something is still not right. Try to fix that.
r? `@petrochenkov`
Generate an iOS LLVM target with a specific version
This commit adds the `LC_VERSION_MIN_IPHONEOS` load command to the Mach-O header generated for `aarch64-apple-ios` binaries. The operating system will look for this load command to determine the minimum supported operating system version and will not allow the binary to run if it's absent. This logic already exists for the simulator toolchain.
I've been using `otool` from a [cctools](https://github.com/tpoechtrager/cctools-port) toolchain to parse the header and validate that this change adds the required load command.
This change appears to be enough to build Rust binaries that can run on a jailbroken iPhone.
Upgrade to LLVM 13
Work in progress update to LLVM 13. Main changes:
* InlineAsm diagnostics reported using SrcMgr diagnostic kind are now handled. Previously these used a separate diag handler.
* Codegen tests are updated for additional attributes.
* Some data layouts have changed.
* Switch `#[used]` attribute from `llvm.used` to `llvm.compiler.used` to avoid SHF_GNU_RETAIN flag introduced in https://reviews.llvm.org/D97448, which appears to trigger a bug in older versions of gold.
* Set `LLVM_INCLUDE_TESTS=OFF` to avoid Python 3.6 requirement.
Upstream issues:
* ~~https://bugs.llvm.org/show_bug.cgi?id=51210 (InlineAsm diagnostic reporting for module asm)~~ Fixed by 1558bb80c0.
* ~~https://bugs.llvm.org/show_bug.cgi?id=51476 (Miscompile on AArch64 due to incorrect comparison elimination)~~ Fixed by 81b106584f.
* https://bugs.llvm.org/show_bug.cgi?id=51207 (Can't set custom section flags anymore). Problematic change reverted in our fork, https://reviews.llvm.org/D107216 posted for upstream revert.
* https://bugs.llvm.org/show_bug.cgi?id=51211 (Regression in codegen for #83623). This is an optimization regression that we may likely have to eat for this release. The fix for #83623 was based on an incorrect premise, and this needs to be properly addressed in the MergeICmps pass.
The [compile-time impact](https://perf.rust-lang.org/compare.html?start=ef9549b6c0efb7525c9b012148689c8d070f9bc0&end=0983094463497eec22d550dad25576a894687002) is mixed, but quite positive as LLVM upgrades go.
The LLVM 13 final release is scheduled for Sep 21st. The current nightly is scheduled for stable release on Oct 21st.
r? `@ghost`
Without the specific version, the mach-o header will be missing the
minimum supported operating system version. This is mandatory for
running Rust binaries on iOS devices.
Add support for clobber_abi to asm!
This PR adds the `clobber_abi` feature that was proposed in #81092.
Fixes#81092
cc `@rust-lang/wg-inline-asm`
r? `@nagisa`
Add c_enum_min_bits target spec field, use for arm-none and thumb-none targets
Fixes https://github.com/rust-lang/rust/issues/87917
<s>Haven't tested this yet, still playing around.</s>
This seems to fix the issue.
* This commit adds the aarch64-unknown-uefi target and also adds it into
the supported targets list under the tier-3 target table.
* Uses the small code model by default
Signed-off-by: Andy-Python-Programmer <andypythonappdeveloper@gmail.com>
rfc3052 followup: Remove authors field from Cargo manifests
Since RFC 3052 soft deprecated the authors field, hiding it from
crates.io, docs.rs, and making Cargo not add it by default, and it is
not generally up to date/useful information for contributors, we may as well
remove it from crates in this repo.
Since RFC 3052 soft deprecated the authors field anyway, hiding it from
crates.io, docs.rs, and making Cargo not add it by default, and it is
not generally up to date/useful information, we should remove it from
crates in this repo.
Use small code model for UEFI targets
* Since the code model only applies to the code and not the data and the code model
only applies to functions you call through using `call`, `jmp` and data with `lea`, etc…
If you are calling functions using the function pointers from the UEFI structures the code
model does not apply in that case. It’s just related to the address space size of your own binary.
Since UEFI (uefi is all relocatable) uses relocatable PEs (relocatable code does not care about the
code model) so, we use the small code model here.
* Since applications don't usually take gigabytes of memory, setting the
target to use the small code model should result in better codegen (comparable
with majority of other targets).
Large code models are also known for generating horrible code, for
example 16 bytes of code to load a single 8-byte value.
Signed-off-by: Andy-Python-Programmer <andypythonappdeveloper@gmail.com>
Do not allow JSON targets to set is-builtin: true
Note that this will affect (and make builds fail for) all of the projects out there that have target files invalid in this way. Crater, however, does not really cover these kinds of the codebases, so it is quite difficult to measure the impact. That said, the target files invalid in this way can start causing build failures each time LLVM is upgraded, anyway, so it is probably a good opportunity to disallow this property, entirely.
Another approach considered was to simply not parse this field anymore, which would avoid making the builds explicitly fail, but it wasn't clear to me if `is-builtin` was always set unintentionally… In case this was the case, I'd expect people to file a feature request stating specifically for what purpose they were using `is-builtin`.
Fixes#86017
* Since the code model only applies to the code and not the data and the code model
only applies to functions you call through using `call`, `jmp` and data with `lea`, etc…
If you are calling functions using the function pointers from the UEFI structures the code
model does not apply in that case. It’s just related to the address space size of your own binary.
Since UEFI (uefi is all relocatable) uses relocatable PEs (relocatable code does not care about the
code model) so, we use the small code model here.
* Since applications don't usually take gigabytes of memory, setting the
target to use the small code model should result in better codegen (comparable
with majority of other targets).
Large code models are also known for generating horrible code, for
example 16 bytes of code to load a single 8-byte value.
* Use the LLVM default code model for the architecture for the
x86_64-unknown-uefi targets. For reference small is the default
code model on x86 in LLVM: <7de2173c2a/llvm/lib/Target/X86/X86TargetMachine.cpp (L204)>
* Remove the comments too as they are not UEFI-specific and applies
to pretty much any target. I added them before as I was explicitily
setting the code model to small.
Signed-off-by: Andy-Python-Programmer <andypythonappdeveloper@gmail.com>
target abi
Implement cfg(target_abi) (RFC 2992)
Add an `abi` field to `TargetOptions`, defaulting to "". Support using
`cfg(target_abi = "...")` for conditional compilation on that field.
Gated by `feature(cfg_target_abi)`.
Add a test for `target_abi`, and a test for the feature gate.
Add `target_abi` to tidy as a platform-specific cfg.
Update targets to use `target_abi`
All eabi targets have `target_abi = "eabi".`
All eabihf targets have `target_abi = "eabihf"`.
`armv6_unknown_freebsd` and `armv7_unknown_freebsd` have `target_abi = "eabihf"`.
All abi64 targets have `target_abi = "abi64"`.
All ilp32 targets have `target_abi = "ilp32"`.
All softfloat targets have `target_abi = "softfloat"`.
All *-uwp-windows-* targets have `target_abi = "uwp"`.
All spe targets have `target_abi = "spe"`.
All macabi targets have `target_abi = "macabi"`.
aarch64-apple-ios-sim has `target_abi = "sim"`.
`x86_64-fortanix-unknown-sgx` has `target_abi = "fortanix"`.
`x86_64-unknown-linux-gnux32` has `target_abi = "x32"`.
Add FIXME entries for targets for which existing values need to change
once `cfg_target_abi` becomes stable. (All of them are tier 3 targets.)
Add a test for `target_abi` in `--print cfg`.
Add clobber-only register classes for asm!
These are needed to properly express a function call ABI using a clobber
list, even though we don't support passing actual values into/out of
these registers.
These are needed to properly express a function call ABI using a clobber
list, even though we don't support passing actual values into/out of
these registers.
All eabi targets have target_abi = "eabi".
All eabihf targets have target_abi = "eabihf".
armv6_unknown_freebsd and armv7_unknown_freebsd have target_abi = "eabihf".
All abi64 targets have target_abi = "abi64".
All ilp32 targets have target_abi = "ilp32".
All softfloat targets have target_abi = "softfloat".
All *-uwp-windows-* targets have target_abi = "uwp".
All spe targets have target_abi = "spe".
All macabi targets have target_abi = "macabi".
aarch64-apple-ios-sim has target_abi = "sim".
x86_64-fortanix-unknown-sgx has target_abi = "fortanix".
x86_64-unknown-linux-gnux32 has target_abi = "x32".
Add FIXME entries for targets for which existing values need to change
once cfg_target_abi becomes stable. (All of them are tier 3 targets.)
Add a test for target_abi in `--print cfg`.
Add an `abi` field to `TargetOptions`, defaulting to "". Support using
`cfg(target_abi = "...")` for conditional compilation on that field.
Gated by `feature(cfg_target_abi)`.
Add a test for `target_abi`, and a test for the feature gate.
Add `target_abi` to tidy as a platform-specific cfg.
This does not add an abi to any existing target.
It makes very little sense to maintain denylists of ABIs when, as far as
non-generic ABIs are concerned, targets usually only support a small
subset of the available ABIs.
This has historically been a cause of bugs such as us allowing use of
the platform-specific ABIs on x86 targets – these in turn would cause
LLVM errors or assertions to fire.
Fixes#57182
Sponsored by: standard.ai
This PR adds ability for the target specifications to specify frame
pointer emission type that's not just “always” or “whatever cg decides”.
In particular there's a new mode that allows omission of the frame
pointer for leaf functions (those that don't call any other functions).
We then set this new mode for Aarch64-based Apple targets.
Fixes#86196
Emit warnings for unused fields in custom targets.
Add a warning which lists any fields in a custom target `json` file that aren't used. Currently unrecognized fields are ignored so, for example, a typo in the `json` will silently produce a target which isn't the one intended.
Tweak wasm_base target spec to indicate linker is not GNU and update linker inferring logic for wasm-ld.
Reported via [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/wasi.20linker.20unknown.20argument.3A.20--as-needed): we try passing `--as-needed` to the linker if it's GNU ld which `wasm-ld` is not. Usually this isn't an issue for wasm as we would use the WasmLd linker driver but because the linker in question (`wasm32-unknown-wasi-wasm-ld`) ended with `-ld` our linker inferring [logic](f64503eb55/compiler/rustc_codegen_ssa/src/back/link.rs (L957-L1040)) used the `GccLinker` implementations. (UPD: The linker inferring logic actually didn't apply in this case because the linker is actually invoked through gcc in the reported issue. But it's still worth updating the logic I think.)
This change then has 2 parts:
1. Update wasm_base target spec to indicate `linker_is_gnu: false` plus a few additions of `target.is_like_wasm` to handle flags `wasm-ld` does in fact support.
2. Improve the linker detection logic to properly determine the correct flavor of wasm linker we're using when we can.
We need to add the new `target.is_like_wasm` branches to handle the case where the "linker" used could be something like clang which would then under the hood call wasm-ld.
BPF target support
This adds `bpfel-unknown-none` and `bpfeb-unknown-none`, two new no_std targets that generate little and big endian BPF. The approach taken is very similar to the cuda target, where `TargetOptions::obj_is_bitcode` is enabled and code generation is done by the linker.
I added the targets to `dist-various-2`. There are [some tests](https://github.com/alessandrod/bpf-linker/tree/main/tests/assembly) in bpf-linker and I'm planning to add more. Those are currently not ran as part of rust CI.
wasm: Make simd types passed via indirection again
This commit updates wasm target specs to use `simd_types_indirect: true`
again. Long ago this was added since wasm simd types were always
translated to `v128` under-the-hood in LLVM, meaning that it didn't
matter whether that target feature was enabled or not. Now, however,
`v128` is conditionally used in codegen depending on target features
enabled, meaning that it's possible to get linker errors about different
signatures in code that correctly uses simd types. The fix is the same
as for all other platforms, which is to pass the type indirectly.
Remove unused feature gates
The first commit removes a usage of a feature gate, but I don't expect it to be controversial as the feature gate was only used to workaround a limitation of rust in the past. (closures never being `Clone`)
The second commit uses `#[allow_internal_unstable]` to avoid leaking the `trusted_step` feature gate usage from inside the index newtype macro. It didn't work for the `min_specialization` feature gate though.
The third commit removes (almost) all feature gates from the compiler that weren't used anyway.
This commit updates wasm target specs to use `simd_types_indirect: true`
again. Long ago this was added since wasm simd types were always
translated to `v128` under-the-hood in LLVM, meaning that it didn't
matter whether that target feature was enabled or not. Now, however,
`v128` is conditionally used in codegen depending on target features
enabled, meaning that it's possible to get linker errors about different
signatures in code that correctly uses simd types. The fix is the same
as for all other platforms, which is to pass the type indirectly.
Turn off frame pointer elimination on all Apple platforms.
This ends up disabling frame pointer elimination on aarch64_apple_darwin
which matches what clang does by default along with the
aarch64_apple_ios and x86_64_apple_darwin targets.
Further, the Apple docs "Writing ARM64 Code for Apple Platforms" has a section
called "Respect the Purpose of Specific CPU Registers" which
specifically calls out the frame pointer register (x29):
The frame pointer register (x29) must always address a valid frame
record. Some functions — such as leaf functions or tail calls — may
opt not to create an entry in this list As a result, stack traces
are always meaningful, even without debug information.
Other platforms are updated to not override the default.
This ends up disabling frame pointer elimination on aarch64_apple_darwin
which matches what clang does by default along with the
aarch64_apple_ios and x86_64_apple_darwin targets.
Further, the Apple docs "Writing ARM64 Code for Apple Platforms" has a section
called "Respect the Purpose of Specific CPU Registers" which
specifically calls out the frame pointer register (x29):
The frame pointer register (x29) must always address a valid frame
record. Some functions — such as leaf functions or tail calls — may
opt not to create an entry in this list As a result, stack traces
are always meaningful, even without debug information.
Other platforms are updated to not override the default.
CTFE core engine allocation & memory API improvemenets
This is a first step towards https://github.com/rust-lang/miri/issues/841.
- make `Allocation` API offset-based (no more making up `Pointer`s just to access an `Allocation`)
- make `Memory` API higher-level (combine checking for access and getting access into one operation)
The Miri-side PR is at https://github.com/rust-lang/miri/pull/1804.
r? `@oli-obk`
Only pass --[no-]gc-sections if linker is GNU ld.
Fixes a regression from #84468 where linking now fails with solaris linkers. LinkerFlavor::Gcc does not always mean GNU ld specifically. And in the case of at least the solaris ld in illumos, that flag is unrecognized and will cause the linking step to fail.
Even though removing the `is_like_solaris` branch from `gc_sections` in #84468 made sense as `-z ignore/record` are more analogous to the `--[no-]-as-needed` flags, it inadvertently caused solaris linkers to be passed the `--gc-sections` flag. So let's just change it to be more explicit about when we pass those flags.
Fix unused attributes on macro_rules.
The `unused_attributes` lint wasn't firing on attributes of `macro_rules` definitions. The consequence is that many attributes are silently ignored on `macro_rules`. The reason is that `unused_attributes` is a late-lint pass, and only has access to the HIR, which does not have macro_rules definitions.
My solution here is to change `non_exported_macro_attrs` to be `macro_attrs` (a list of all attributes used for `macro_rules`, instead of just those for `macro_export`), and then to check this list in the `unused_attributes` lint. There are a number of alternate approaches, but this seemed the most reliable and least invasive. I am open to completely different approaches, though.
One concern is that I don't fully understand the implications of extending `non_exported_macro_attrs` to include non-exported macros. That list was originally added in #62042 to handle stability attributes, so I suspect it was just an optimization since that was all that was needed. It was later extended to be included in SVH in #83901. #80641 also added a use to check for `invalid` attributes, which seems a little odd to me (it didn't validate non-exported macros, and seems highly specific).
Overall, there doesn't seem to be a clear story of when `unused_attributes` should be used versus an error like E0518. I considered alternatively using an "allow list" of built-in attributes that can be used on macro_rules (allow, warn, deny, forbid, cfg, cfg_attr, macro_export, deprecated, doc), but I feel like that could be a pain to maintain.
Some built-in attributes already present hard-errors when used with macro_rules. These are each hard-coded in various places:
- `derive`
- `test` and `bench`
- `proc_macro` and `proc_macro_derive`
- `inline`
- `global_allocator`
The primary motivation is that I sometimes see people use `#[macro_use]` in front of `macro_rules`, which indicates there is some confusion out there (evident that there was even a case of it in rustc).
