Error on invalid macho section specifier by folkertdev · Pull Request #155065 · rust-lang/rust

folkertdev · 2026-04-09T20:11:02Z

The macho section specifier used by #[link_section = "..."] is more strict than e.g. the one for elf. LLVM will error when you get it wrong, which is easy to do if you're used to elf. So, provide some guidance for the simplest mistakes, based on the LLVM validation.

Currently compilation fails with an LLVM error, see https://godbolt.org/z/WoE8EdK1K.

The LLVM validation logic is at

https://github.com/llvm/llvm-project/blob/a0f0d6342e0cd75b7f41e0e6aae0944393b68a62/llvm/lib/MC/MCSectionMachO.cpp#L199-L203

LLVM validates the other components of the section specifier too, but it feels a bit fragile to duplicate those checks. If you get that far, hopefully the LLVM errors will be sufficient to get unstuck.

sidequest from #147811

r? JonathanBrouwer

specifically, is this the right place for this sort of validation? rustc_attr_parsing also does some validation.

rustbot · 2026-04-09T20:11:06Z

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

folkertdev · 2026-04-09T20:14:59Z

just in case we're doing something weird that never got built or linked

@bors try jobs=aarch64-apple

error on invalid macho section specifier try-job: aarch64-apple

JonathanBrouwer · 2026-04-09T20:33:01Z

specifically, is this the right place for this sort of validation? rustc_attr_parsing also does some validation.

We're trying to move as many checks as possible to attribute parsing, with the "parse, don't validate" mentality, so if an attribute gets through parsing you can assume it is correct. Therefore I'd like this to be in the attribute parser

rustbot · 2026-04-09T20:41:53Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

rust-bors · 2026-04-09T21:44:51Z

💔 Test for 3e6930f failed: CI. Failed job:

try - aarch64-apple (web logs, enhanced plaintext logs)

…, r=JonathanBrouwer error on invalid macho section specifier The macho section specifier used by `#[link_section = "..."]` is more strict than e.g. the one for elf. LLVM will error when you get it wrong, which is easy to do if you're used to elf. So, provide some guidance for the simplest mistakes, based on the LLVM validation. Currently compilation fails with an LLVM error, see https://godbolt.org/z/WoE8EdK1K. The LLVM validation logic is at https://github.com/llvm/llvm-project/blob/a0f0d6342e0cd75b7f41e0e6aae0944393b68a62/llvm/lib/MC/MCSectionMachO.cpp#L199-L203 LLVM validates the other components of the section specifier too, but it feels a bit fragile to duplicate those checks. If you get that far, hopefully the LLVM errors will be sufficient to get unstuck. --- sidequest from rust-lang#147811 r? JonathanBrouwer specifically, is this the right place for this sort of validation? `rustc_attr_parsing` also does some validation.

rust-rfcbot · 2026-04-15T15:59:23Z

🔔 This is now entering its final comment period, as per the review above. 🔔

bjorn3 · 2026-04-15T17:29:43Z

Rfcbot didn't catch your review Niko.

rust-rfcbot · 2026-04-25T16:04:02Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

rustbot · 2026-04-25T18:06:51Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

folkertdev · 2026-04-25T20:26:18Z

@bors r=JonathanBrouwer

rust-bors · 2026-04-25T20:26:21Z

📌 Commit a4f5c6e has been approved by JonathanBrouwer

It is now in the queue for this repository.

…, r=JonathanBrouwer Error on invalid macho section specifier The macho section specifier used by `#[link_section = "..."]` is more strict than e.g. the one for elf. LLVM will error when you get it wrong, which is easy to do if you're used to elf. So, provide some guidance for the simplest mistakes, based on the LLVM validation. Currently compilation fails with an LLVM error, see https://godbolt.org/z/WoE8EdK1K. The LLVM validation logic is at https://github.com/llvm/llvm-project/blob/a0f0d6342e0cd75b7f41e0e6aae0944393b68a62/llvm/lib/MC/MCSectionMachO.cpp#L199-L203 LLVM validates the other components of the section specifier too, but it feels a bit fragile to duplicate those checks. If you get that far, hopefully the LLVM errors will be sufficient to get unstuck. --- sidequest from rust-lang#147811 r? JonathanBrouwer specifically, is this the right place for this sort of validation? `rustc_attr_parsing` also does some validation.

…uwer Rollup of 4 pull requests Successful merges: - #146181 (Add intrinsic for launch-sized workgroup memory on GPUs) - #155065 (Error on invalid macho section specifier) - #155676 ( Reject implementing const Drop for types that are not const `Destruct` already) - #155783 (Do not suggest internal cfg trace attributes)

…uwer Rollup of 9 pull requests Successful merges: - #146181 (Add intrinsic for launch-sized workgroup memory on GPUs) - #154803 (Fix ICE from cfg_attr_trace ) - #155065 (Error on invalid macho section specifier) - #155485 (Add an edge-case test for `--remap-path-prefix` for `rustc` & `rustdoc`) - #155659 (cleanup, restructure and merge `tests/ui/deriving` into `tests/ui/derives`) - #155676 ( Reject implementing const Drop for types that are not const `Destruct` already) - #155696 (Add a higher-level API for parsing attributes) - #155769 (triagebot.toml: Ping Enselic when tests/debuginfo/basic-stepping.rs changes) - #155783 (Do not suggest internal cfg trace attributes)

Rollup merge of #155065 - folkertdev:macho-section-specifier, r=JonathanBrouwer Error on invalid macho section specifier The macho section specifier used by `#[link_section = "..."]` is more strict than e.g. the one for elf. LLVM will error when you get it wrong, which is easy to do if you're used to elf. So, provide some guidance for the simplest mistakes, based on the LLVM validation. Currently compilation fails with an LLVM error, see https://godbolt.org/z/WoE8EdK1K. The LLVM validation logic is at https://github.com/llvm/llvm-project/blob/a0f0d6342e0cd75b7f41e0e6aae0944393b68a62/llvm/lib/MC/MCSectionMachO.cpp#L199-L203 LLVM validates the other components of the section specifier too, but it feels a bit fragile to duplicate those checks. If you get that far, hopefully the LLVM errors will be sufficient to get unstuck. --- sidequest from #147811 r? JonathanBrouwer specifically, is this the right place for this sort of validation? `rustc_attr_parsing` also does some validation.

rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 9, 2026

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rust-bors Bot pushed a commit that referenced this pull request Apr 9, 2026

Auto merge of #155065 - folkertdev:macho-section-specifier, r=<try>

3e6930f

error on invalid macho section specifier try-job: aarch64-apple

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folkertdev force-pushed the macho-section-specifier branch from 35e0a3f to c90d31f Compare April 9, 2026 20:21

rustbot added the A-rustdoc-json Area: Rustdoc JSON backend label Apr 9, 2026

JonathanBrouwer reviewed Apr 9, 2026

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Comment thread tests/ui/linkage-attr/link-section-macho.rs

JonathanBrouwer requested changes Apr 9, 2026

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 9, 2026

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folkertdev force-pushed the macho-section-specifier branch from c90d31f to 30b9c6e Compare April 9, 2026 22:49

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JonathanBrouwer force-pushed the macho-section-specifier branch from 30b9c6e to db42ae2 Compare April 10, 2026 09:31

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JonathanBrouwer mentioned this pull request Apr 10, 2026

Rollup of 2 pull requests #155090

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rust-rfcbot added the final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. label Apr 15, 2026

rust-rfcbot removed the proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. label Apr 15, 2026

traviscross removed I-lang-nominated Nominated for discussion during a lang team meeting. P-lang-drag-1 Lang team prioritization drag level 1. https://rust-lang.zulipchat.com/#narrow/channel/410516-t-lang labels Apr 15, 2026

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This was referenced Apr 19, 2026

Parse and set Mach-O section type and attributes rust-lang/rustc_codegen_cranelift#1648

Draft

Document #[link_section = "..."] format rust-lang/reference#2236

Open

rustbot mentioned this pull request Apr 25, 2026

Tracking issue for release notes of #155065: Error on invalid macho section specifier #155785

Open

error on invalid macho section specifier

a4f5c6e

folkertdev force-pushed the macho-section-specifier branch from 7aeba4e to a4f5c6e Compare April 25, 2026 18:06

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 25, 2026

folkertdev mentioned this pull request Apr 25, 2026

special link_name confuses LLVM #155776

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JonathanBrouwer mentioned this pull request Apr 25, 2026

Rollup of 4 pull requests #155793

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JonathanBrouwer mentioned this pull request Apr 25, 2026

Rollup of 9 pull requests #155796

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rust-bors Bot merged commit 1fe66ee into rust-lang:main Apr 26, 2026
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rustbot added this to the 1.97.0 milestone Apr 26, 2026

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folkertdev commented Apr 9, 2026 •

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