Align attr fixes #143206

Jules-Bertholet · 2025-06-29T17:05:48Z

Remove references to the superseded repr(align) syntax
Allow the attribute on fn items in extern blocks
Test attribute in combination with async fn and dyn

r? workingjubilee

@rustbot label A-attributes F-fn_align T-compiler

rustbot · 2025-06-29T17:05:53Z

rustbot has assigned @WaffleLapkin.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

rustbot · 2025-06-29T17:05:55Z

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

cc @jdonszelmann

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

Some changes occurred in compiler/rustc_codegen_ssa/src/codegen_attrs.rs

cc @jdonszelmann

rustbot · 2025-06-29T19:13:40Z

workingjubilee is currently at their maximum review capacity.
They may take a while to respond.

bors · 2025-07-01T09:35:37Z

☔ The latest upstream changes (presumably #143267) made this pull request unmergeable. Please resolve the merge conflicts.

workingjubilee · 2025-07-01T18:44:54Z

This requires rebase.

workingjubilee · 2025-07-01T18:45:11Z

@rustbot author

rustbot · 2025-07-01T18:45:14Z

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

Jules-Bertholet · 2025-07-01T19:00:11Z

@rustbot ready

workingjubilee

This is good as-is but I would like to see more tests. You can add them now or as a followup PR or open an issue instead. r=me either way.

tests/codegen/align-fn.rs

workingjubilee · 2025-07-01T19:35:45Z

tests/codegen/align-fn.rs

+    #[align(32)]
+    #[align(256)]
+    extern "C" fn align_unmangled() {}


Weren't we going to warn on applying align twice?

I mean that shouldn't affect the codegen test, I'm just realizing that I don't know for sure if we have a test that does check that we warn.

It would be nice to have a warning, but it’s not required for the MVP. It hasn’t been implemented yet.

workingjubilee · 2025-07-01T19:38:33Z

tests/ui/attributes/fn-align-dyn.rs

+#![feature(fn_align)]
+
+trait Test {
+    #[align(4096)]


4096 is pretty big but I am realizing I don't see a test for oversized aligns that we should definitely reject, I think.

4096 I believe is the highest align that should work more or less everywhere. Because this test relies on converting to a function pointer, choosing a high value minimizes the chance of “getting lucky”.

Rejecting high alignments on platforms that don’t support them is being worked on by others, I think.

tests/ui/attributes/malformed-fn-align.rs

workingjubilee · 2025-07-01T19:44:58Z

@bors delegate+

bors · 2025-07-01T19:45:02Z

✌️ @Jules-Bertholet, you can now approve this pull request!

If @workingjubilee told you to "r=me" after making some further change, please make that change, then do @bors r=@workingjubilee

workingjubilee · 2025-07-01T19:50:00Z

It's also possible that the tests already exist and I was just too ferrisClueless.jpg to find them

Jules-Bertholet · 2025-07-01T20:16:43Z

@bors r=@workingjubilee

bors · 2025-07-01T20:16:46Z

📌 Commit 440bf29 has been approved by workingjubilee

It is now in the queue for this repository.

…r=workingjubilee Align attr fixes - Remove references to the superseded `repr(align)` syntax - Allow the attribute on fn items in `extern` blocks - Test attribute in combination with `async fn` and `dyn` r? workingjubilee `@rustbot` label A-attributes F-fn_align T-compiler

Rollup of 12 pull requests Successful merges: - #141829 (Specialize sleep_until implementation for unix (except mac)) - #141847 (Explain `TOCTOU` on the top of `std::fs`, and reference it in functions) - #142138 (Add `Vec::into_chunks`) - #142321 (Expose elf abi on ppc64 targets) - #142568 (Use the .drectve section for exporting symbols from dlls on Windows) - #142886 (ci: aarch64-gnu: Stop skipping `panic_abort_doc_tests`) - #143038 (avoid suggesting traits from private dependencies) - #143194 (fix bitcast of single-element SIMD vectors) - #143206 (Align attr fixes) - #143258 (Don't recompute `DisambiguatorState` for every RPITIT in trait definition) - #143260 (Use the correct export kind for __rust_alloc_error_handler_should_panic) - #143274 (ci: support optional jobs) r? `@ghost` `@rustbot` modify labels: rollup

…r=workingjubilee Align attr fixes - Remove references to the superseded `repr(align)` syntax - Allow the attribute on fn items in `extern` blocks - Test attribute in combination with `async fn` and `dyn` r? workingjubilee ``@rustbot`` label A-attributes F-fn_align T-compiler

rustbot assigned WaffleLapkin Jun 29, 2025

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 Jun 29, 2025

rustbot added the F-fn_align `#![feature(fn_align)]` label Jun 29, 2025

rustbot assigned workingjubilee Jun 29, 2025

rustbot unassigned WaffleLapkin Jun 29, 2025

rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 1, 2025

rustbot added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jul 1, 2025

Jules-Bertholet added 4 commits July 1, 2025 14:56

Remove repr(align) code

308ef8d

Support #[align(…)] on fns in extern blocks

278f4f4

Test async fn

55d0210

Add test for dyn alignment

0382357

Jules-Bertholet force-pushed the align-attr-fixes branch from 91791f5 to 0382357 Compare July 1, 2025 19:00

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 1, 2025

workingjubilee approved these changes Jul 1, 2025

View reviewed changes

Jules-Bertholet added 2 commits July 1, 2025 15:58

Add FIXME for gen et al

233e2ef

Add more tests for invalid alignments

440bf29

Jules-Bertholet force-pushed the align-attr-fixes branch from 2e6c84a to 440bf29 Compare July 1, 2025 20:16

bors 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-review Status: Awaiting review from the assignee but also interested parties. labels Jul 1, 2025

jhpratt mentioned this pull request Jul 1, 2025

Rollup of 12 pull requests #143305

Closed

jhpratt mentioned this pull request Jul 2, 2025

Rollup of 11 pull requests #143311

Open

Align attr fixes #143206

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Align attr fixes #143206

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Jules-Bertholet commented Jun 29, 2025 •

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