[RFC] Explicit ABI in `extern` #3722

m-ou-se · 2024-10-30T10:46:06Z

joshtriplett · 2024-10-30T10:53:02Z

Very much a fan of making this change. As noted in the RFC, it's very late for the 2024 edition. That said, I would personally not object to trying for 2024 if we can get the necessary migration lint in place.

One way or another, I personally think T-lang should approve this RFC, with the guidance of "whenever it's ready", and defer to those wrangling the edition to decide whether this happens in 2024 or 2027.

m-ou-se · 2024-10-30T12:45:45Z

Implementation, including migration lint: rust-lang/rust#132357

traviscross · 2024-10-30T14:24:33Z

@rustbot labels -A-edition-2024

This makes sense to me as a language matter also.

With the edition hat on, though, and after consulting with the rest of the edition team, it's unfortunately just too late to accept a new language item like this for Rust 2024. This is due to the testing and release timeline, where we are in it, and how these kind of changes affect that.

Let's make sure it makes the next edition, assuming the rest of the lang team likes this also.

tmandry · 2024-10-30T16:25:29Z

The lang team discussed this in our meeting today and everyone was in favor of the change. Since it's too late for 2024 Edition, this RFC is not time sensitive, but we might as well approve it for the next edition.

Meanwhile, there is an existing missing_abi lint that we should upgrade to warn-by-default in all editions. We should do that in a separate FCP. (There was some discussion of rolling this out starting with 2024 – but that should not happen as part of the initial edition release, or it would fall under the testing and documentation requirements that we already said it was too late to do for 2024.)

@rfcbot fcp merge

rfcbot · 2024-10-30T16:25:33Z

Team member @tmandry has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns.
See this document for info about what commands tagged team members can give me.

est31 · 2024-10-30T16:51:00Z

text/3722-explicit-abi.md

+# Future possibilities
+
+In the future, we might want to add a new default ABI.
+For example, if `extern "stable-rust-abi"` becomes a thing and e.g. dynamically linking Rust from Rust becomes very popular, it might make sense to make that the default when writing `extern fn` without an ABI.


I don't think, if there is a default, it should be anything other than "C" because it raises the stakes of getting the edition wrong.

It would mean that getting the edition parameter wrong causes a breakage in ABI. Which is fine if it's caught by an error but this is not guaranteed, it could also just lead to silent UB, segfaults, etc.

There is some such flags in Rust already, but flags have been removed with it affecting the ABI being one of the reasons.

Sure. The future possibilities are a separate discussion if/when they are proposed. Definitely not part of what I'm proposing now. :)

It is easy to read anything in the future possibilities section as an endorsement of that idea. It would be nice to either remove that paragraph or incorporate the known issues into the text.

Also I doubt that dynamically linking Rust to Rust will become more popular than interfacing with the non-Rust world, which (mostly) goes via the "C" ABI.

It is easy to read anything in the future possibilities section as an endorsement of that idea.

This is something that we really, really should try to avert in the RFC process. Accepting an RFC is not any kind of endorsement or directional approval of things in the future possibilities section.

scottmcm · 2024-10-30T17:38:26Z

I like being explicit here. The burden of also saying "C" is small compared to also having to have said extern, so might as well -- especially as more people actually want "C-unwind".

@rfcbot reviewed

I agree that we probably shouldn't change to a new default for some time, if ever.

text/3722-explicit-abi.md

traviscross · 2024-10-30T19:11:06Z

@rfcbot reviewed
@rustbot labels -I-lang-nominated

We discussed this in lang triage today, resulting in tmandry's proposed FCP above, which sounds right to me.

m-ou-se · 2024-10-31T10:47:29Z

Meanwhile, there is an existing missing_abi lint that we should upgrade to warn-by-default in all editions. We should do that in a separate FCP.

This PR makes the lint warn-by-default: rust-lang/rust#132397

…rrors Improve missing_abi lint This is for the migration lint for rust-lang/rfcs#3722 It is not yet marked as an edition migration lint, because `Edition2027` doesn't exist yet. The lint now includes a machine applicable suggestion: ``` warning: extern declarations without an explicit ABI are deprecated --> src/main.rs:3:1 | 3 | extern fn a() {} | ^^^^^^ help: explicitly specify the C ABI: `extern "C"` | ```

Rollup merge of rust-lang#132357 - m-ou-se:explicit-abi, r=compiler-errors Improve missing_abi lint This is for the migration lint for rust-lang/rfcs#3722 It is not yet marked as an edition migration lint, because `Edition2027` doesn't exist yet. The lint now includes a machine applicable suggestion: ``` warning: extern declarations without an explicit ABI are deprecated --> src/main.rs:3:1 | 3 | extern fn a() {} | ^^^^^^ help: explicitly specify the C ABI: `extern "C"` | ```

rfcbot · 2024-11-20T16:28:09Z

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

madsmtm · 2024-11-29T08:24:44Z

text/3722-explicit-abi.md

+
+- This is a breaking change and needs to be done in a new edition.
+
+# Prior art


Other prior art: rustfmt converts extern {} to extern "C" {}, see the docs.

rfcbot · 2024-11-30T16:28:18Z

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.

This will be merged soon.

Add explicit abi RFC.

d0699ca

m-ou-se force-pushed the explicit-abi branch from 11625fc to d0699ca Compare October 30, 2024 10:46

Add rfc number.

36f6074

m-ou-se mentioned this pull request Oct 30, 2024

Improve missing_abi lint rust-lang/rust#132357

Merged

rustbot removed the A-edition-2024 Area: The 2024 edition label Oct 30, 2024

tmandry removed the T-edition Relevant to the edition team, which will review and decide on this RFC. label Oct 30, 2024

rfcbot added proposed-final-comment-period Currently awaiting signoff of all team members in order to enter the final comment period. disposition-merge This RFC is in PFCP or FCP with a disposition to merge it. labels Oct 30, 2024

tmandry added the T-edition Relevant to the edition team, which will review and decide on this RFC. label Oct 30, 2024

est31 reviewed Oct 30, 2024

View reviewed changes

calebcartwright mentioned this pull request Oct 30, 2024

Style Guide prescriptions on ABI explicitness rust-lang/style-team#199

Open

traviscross reviewed Oct 30, 2024

View reviewed changes

text/3722-explicit-abi.md Outdated Show resolved Hide resolved

rustbot removed the I-lang-nominated Indicates that an issue has been nominated for prioritizing at the next lang team meeting. label Oct 30, 2024

Resolve unresolved questions.

3d04a08

m-ou-se mentioned this pull request Oct 31, 2024

Make missing_abi lint warn-by-default. rust-lang/rust#132397

Open

rfcbot added final-comment-period Will be merged/postponed/closed in ~10 calendar days unless new substational objections are raised. and removed proposed-final-comment-period Currently awaiting signoff of all team members in order to enter the final comment period. labels Nov 20, 2024

madsmtm reviewed Nov 29, 2024

View reviewed changes

rfcbot added finished-final-comment-period The final comment period is finished for this RFC. and removed final-comment-period Will be merged/postponed/closed in ~10 calendar days unless new substational objections are raised. labels Nov 30, 2024

rfcbot added the to-announce label Nov 30, 2024

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

[RFC] Explicit ABI in `extern` #3722

[RFC] Explicit ABI in `extern` #3722

m-ou-se commented Oct 30, 2024 •

edited

Loading

joshtriplett commented Oct 30, 2024 •

edited

Loading

m-ou-se commented Oct 30, 2024

traviscross commented Oct 30, 2024

tmandry commented Oct 30, 2024

rfcbot commented Oct 30, 2024 •

edited by pnkfelix

Loading

est31 Oct 30, 2024

m-ou-se Oct 31, 2024

est31 Nov 1, 2024 •

edited

Loading

joshtriplett Nov 20, 2024 •

edited

Loading

scottmcm commented Oct 30, 2024

traviscross commented Oct 30, 2024

m-ou-se commented Oct 31, 2024

rfcbot commented Nov 20, 2024

madsmtm Nov 29, 2024 •

edited

Loading

rfcbot commented Nov 30, 2024


		- This is a breaking change and needs to be done in a new edition.

		# Prior art

[RFC] Explicit ABI in extern #3722

Are you sure you want to change the base?

[RFC] Explicit ABI in extern #3722

Conversation

m-ou-se commented Oct 30, 2024 • edited Loading

joshtriplett commented Oct 30, 2024 • edited Loading

m-ou-se commented Oct 30, 2024

traviscross commented Oct 30, 2024

tmandry commented Oct 30, 2024

rfcbot commented Oct 30, 2024 • edited by pnkfelix Loading

est31 Oct 30, 2024

Choose a reason for hiding this comment

m-ou-se Oct 31, 2024

Choose a reason for hiding this comment

est31 Nov 1, 2024 • edited Loading

Choose a reason for hiding this comment

joshtriplett Nov 20, 2024 • edited Loading

Choose a reason for hiding this comment

scottmcm commented Oct 30, 2024

traviscross commented Oct 30, 2024

m-ou-se commented Oct 31, 2024

rfcbot commented Nov 20, 2024

madsmtm Nov 29, 2024 • edited Loading

Choose a reason for hiding this comment

rfcbot commented Nov 30, 2024

[RFC] Explicit ABI in `extern` #3722

[RFC] Explicit ABI in `extern` #3722

m-ou-se commented Oct 30, 2024 •

edited

Loading

joshtriplett commented Oct 30, 2024 •

edited

Loading

rfcbot commented Oct 30, 2024 •

edited by pnkfelix

Loading

est31 Nov 1, 2024 •

edited

Loading

joshtriplett Nov 20, 2024 •

edited

Loading

madsmtm Nov 29, 2024 •

edited

Loading