mark some target features as 'forbidden' so they cannot be (un)set with -Ctarget-feature
The context for this is https://github.com/rust-lang/rust/issues/116344: some target features change the way floats are passed between functions. Changing those target features is unsound as code compiled for the same target may now use different ABIs.
So this introduces a new concept of "forbidden" target features (on top of the existing "stable " and "unstable" categories), and makes it a hard error to (un)set such a target feature. For now, the x86 and ARM feature `soft-float` is on that list. We'll have to make some effort to collect more relevant features, and similar features from other targets, but that can happen after the basic infrastructure for this landed. (These features are being collected in https://github.com/rust-lang/rust/issues/131799.)
I've made this a warning for now to give people some time to speak up if this would break something.
MCP: https://github.com/rust-lang/compiler-team/issues/780
triagebot: ping wg-const-eval when relevant files change
This adds pings for `@rust-lang/wg-const-eval` when anything in rustc_const_eval changes (in particular, this covers the const checking logic, which was so far not covered by any notifications). I also added pings for things that so far only pinged the Miri group, since those parts are relevant to wg-const-eval as well.
PassWrapper: adapt for new parameter in LLVM
llvm/llvm-project@390300d9f4 added a new parameter to some callbacks, so we have to handle them.
`@rustbot` label: +llvm-main
[core/fmt] Replace checked slice indexing by unchecked to support panic-free code
Fixes#126425
Replace the potentially panicking `[]` indexing with `get_unchecked()` to prevent linking with panic-related code.
Stabilise `const_char_encode_utf16`.
Closes: #130660
This PR stabilises the `const_char_encode_utf16` feature gate (i.e. support for `char::encode_utf16` in constant expressions).
~~Note that the linked tracking issue is as of this writing currently awaiting FCP until 2024-11-02.~~
Remove unnecessary pub enum glob-imports from `rustc_middle::ty`
We used to have an idiom in the compiler where we'd prefix or suffix all the variants of an enum, for example `BoundRegionKind`, with something like `Br`, and then *glob-import* that enum variant directly.
`@noratrieb` brought this up, and I think that it's easier to read when we just use the normal style `EnumName::Variant`.
This PR is a bit large, but it's just naming.
The only somewhat opinionated change that this PR does is rename `BorrowKind::Imm` to `BorrowKind::Immutable` and same for the other variants. I think these enums are used sparingly enough that the extra length is fine.
r? `@noratrieb` or reassign
Remove unnecessary pub enum glob-imports from `rustc_middle::ty`
We used to have an idiom in the compiler where we'd prefix or suffix all the variants of an enum, for example `BoundRegionKind`, with something like `Br`, and then *glob-import* that enum variant directly.
`@noratrieb` brought this up, and I think that it's easier to read when we just use the normal style `EnumName::Variant`.
This PR is a bit large, but it's just naming.
The only somewhat opinionated change that this PR does is rename `BorrowKind::Imm` to `BorrowKind::Immutable` and same for the other variants. I think these enums are used sparingly enough that the extra length is fine.
r? `@noratrieb` or reassign
Improve example of `impl Pattern for &[char]`
The previous version used `['l', 'l']` as pattern, which would suggest that it matches the `ll` of `Hello world` as a whole.
Clippy: Move some attribute lints to be early pass (post expansion)
r? ```@xFrednet```
As a side effect it removes a duplicated warning on line 53 of the `allow_attributes` test. I discussed this with ```@xFrednet``` , and it's mainly to support the attribute rework https://github.com/rust-lang/rust/issues/131229
[rustdoc] Fix `--show-coverage` when JSON output format is used
I realized while looking on the docs.rs page of the `sysinfo` crate that the coverage numbers displayed were wrong:
I realized that it was because `--show-coverage --output-format=json` was relying on the same logic as the JSON output for the doc generation whereas it should not. I fixed it by changing the API for querying `is_json` a bit.
The underlying issue is that JSON output format is stripping reexports of items from private modules.
r? ``@notriddle``
Revert "Avoid nested replacement ranges" from #129346.
It caused a test regression in the `cfg_eval.rs` crate. (The bugfix in #129346 was in a different commit; this commit was just a code simplification.)
r? `@petrochenkov`
remove support for extern-block const intrinsics
This converts all const-callable intrinsics into the "new" form of a regular `fn` with `#[rustc_intrinsic]` attribute. That simplifies some of the logic since those functions can be marked `const fn` like regular functions, so intrinsics no longer need a special case to be considered const-callable at all.
I also added a new attribute `#[rustc_const_stable_intrinsic]` to mark an intrinsic as being ready to be exposed on stable. Previously we used the `#[rustc_const_stable_indirect]` attribute for that, but that attribute had a dual role -- when used on a regular function, it is an entirely safe marker to make this function part of recursive const stability, but on an intrinsic it is a trusted marker requiring special care. It's not great for the same attribute to be sometimes fully checked and safe, and sometimes trusted and requiring special care, so I split this into two attributes.
This also fixes https://github.com/rust-lang/rust/issues/122652 by accepting intrinsics as const-stable if they have a fallback body that is recursively const-stable.
The library changes are best reviewed with whitespace hidden.
r? `@compiler-errors`
More tests for non-exhaustive C-like enums in FFI
Add a few more tests for the `improper_ctypes` lint as found with the [varnish-rs](https://github.com/gquintard/varnish-rs) project.
This follows up on #116831, fixed in #116863 by ``@workingjubilee`` - I have been seeing these fail with the bindgen-generated non-exhaustive enums inside other structs. Seems the issue does not exist in the primary branch, so this PR just makes sure more cases are covered for the future.
Support clobber_abi and vector registers (clobber-only) in PowerPC inline assembly
This supports `clobber_abi` which is one of the requirements of stabilization mentioned in #93335.
This basically does a similar thing I did in https://github.com/rust-lang/rust/pull/130630 to implement `clobber_abi` for s390x, but for powerpc/powerpc64/powerpc64le.
- This also supports vector registers (as `vreg`) as clobber-only, which need to support clobbering of them to implement `clobber_abi`.
- `vreg` should be able to accept `#[repr(simd)]` types as input/output if the unstable `altivec` target feature is enabled, but `core::arch::{powerpc,powerpc64}` vector types, `#[repr(simd)]`, and `core::simd` are all unstable, so the fact that this is currently a clobber-only should not be considered a blocker of clobber_abi implementation or stabilization. So I have not implemented it in this PR.
- See https://github.com/rust-lang/rust/pull/131551 (which is based on this PR) for a PR to implement this.
- (I'm not sticking to whether that PR should be a separate PR or part of this PR, so I can merge that PR into this PR if needed.)
Refs:
- PPC32 SysV: Section "Function Calling Sequence" in [System V Application Binary Interface PowerPC Processor Supplement](https://refspecs.linuxfoundation.org/elf/elfspec_ppc.pdf)
- PPC64 ELFv1: Section 3.2 "Function Calling Sequence" in [64-bit PowerPC ELF Application Binary Interface Supplement](https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html#FUNC-CALL)
- PPC64 ELFv2: Section 2.2 "Function Calling Sequence" in [64-Bit ELF V2 ABI Specification](https://openpowerfoundation.org/specifications/64bitelfabi/)
- AIX: [Register usage and conventions](https://www.ibm.com/docs/en/aix/7.3?topic=overview-register-usage-conventions), [Special registers in the PowerPC®](https://www.ibm.com/docs/en/aix/7.3?topic=overview-special-registers-in-powerpc), [AIX vector programming](https://www.ibm.com/docs/en/aix/7.3?topic=concepts-aix-vector-programming)
- Register definition in LLVM: https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/PowerPC/PPCRegisterInfo.td#L189
If I understand the above four ABI documentations correctly, except for the PPC32 SysV's VR (Vector Registers) and 32-bit AIX (currently not supported by rustc)'s r13, there does not appear to be important differences in terms of implementing `clobber_abi`:
- The above four ABIs are consistent about FPR (0-13: volatile, 14-31: nonvolatile), CR (0-1,5-7: volatile, 2-4: nonvolatile), XER (volatile), and CTR (volatile).
- As for GPR, only the registers we are treating as reserved are slightly different
- r0, r3-r12 are volatile
- r1(sp, reserved), r14-31 are nonvolatile
- r2(reserved) is TOC pointer in PPC64 ELF/AIX, system-reserved register in PPC32 SysV (AFAIK used as thread pointer in Linux/BSDs)
- r13(reserved for non-32-bit-AIX) is thread pointer in PPC64 ELF, small data area pointer register in PPC32 SysV, "reserved under 64-bit environment; not restored across system calls[^r13]" in AIX)
- As for FPSCR, volatile in PPC64 ELFv1/AIX, some fields are volatile only in certain situations (rest are volatile) in PPC32 SysV/PPC64 ELFv2.
- As for VR (Vector Registers), it is not mentioned in PPC32 SysV, v0-v19 are volatile in both in PPC64 ELF/AIX, v20-v31 are nonvolatile in PPC64 ELF, reserved or nonvolatile depending on the ABI ([vec-extabi vs vec-default in LLVM](https://reviews.llvm.org/D89684), we are [using vec-extabi](https://github.com/rust-lang/rust/pull/131341#discussion_r1797693299)) in AIX:
> When the default Vector enabled mode is used, these registers are reserved and must not be used.
> In the extended ABI vector enabled mode, these registers are nonvolatile and their values are preserved across function calls
I left [FIXME comment about PPC32 SysV](https://github.com/rust-lang/rust/pull/131341#discussion_r1790496095) and added ABI check for AIX.
- As for VRSAVE, it is not mentioned in PPC32 SysV, nonvolatile in PPC64 ELFv1, reserved in PPC64 ELFv2/AIX
- As for VSCR, it is not mentioned in PPC32 SysV/PPC64 ELFv1, some fields are volatile only in certain situations (rest are volatile) in PPC64 ELFv2, volatile in AIX
We are currently treating r1-r2, r13 (non-32-bit-AIX), r29-r31, LR, CTR, and VRSAVE as reserved.
We are currently not processing anything about FPSCR and VSCR, but I feel those are things that should be processed by `preserves_flags` rather than `clobber_abi` if we need to do something about them. (However, PPCRegisterInfo.td in LLVM does not seem to define anything about them.)
Replaces #111335 and #124279
cc `@ecnelises` `@bzEq` `@lu-zero`
r? `@Amanieu`
`@rustbot` label +O-PowerPC +A-inline-assembly
[^r13]: callee-saved, according to [LLVM](6a6af0246b/llvm/lib/Target/PowerPC/PPCCallingConv.td (L322)) and [GCC](a9173a50e7/gcc/config/rs6000/rs6000.h (L859)).
Rollup of 6 pull requests
Successful merges:
- #132355 (Fix compiler panic with a large number of threads)
- #132486 (No need to instantiate binder in `confirm_async_closure_candidate`)
- #132544 (Use backticks instead of single quotes for library feature names in diagnostics)
- #132559 (find the generic container rather than simply looking up for the assoc with const arg)
- #132579 (add rustc std workspace crate sources)
- #132583 (Suggest creating unary tuples when types don't match a trait)
r? `@ghost`
`@rustbot` modify labels: rollup
