---
title: Triage meeting 2023-02-21
tags: triage-meeting
---

# T-lang meeting agenda

* Meeting date: 2023-02-21

## Attendance

* Team members: pnkfelix, Josh, Tyler, Scott
* Others: Mark, David, Bryan Garza, Lokathor, Gary Guo

## Meeting roles

* Action item scribe:
* Note-taker: pnkfelix

## Scheduled meetings
- "discuss/resolve `fn { mod { (use) super::...; } }` and its interaction with derive patterns" [lang-team#193](https://github.com/rust-lang/lang-team/issues/193)
- Post monomorphization errors [lang-team#195](https://github.com/rust-lang/lang-team/issues/195)
- "Interface between opsem and lang team" [lang-team#196](https://github.com/rust-lang/lang-team/issues/196)

## Announcements or custom items

(Meeting attendees, feel free to add items here!)

## Action item review

* [Action items list](https://hackmd.io/gstfhtXYTHa3Jv-P_2RK7A)

## Pending lang team project proposals

None.

## PRs on the lang-team repo
### "Updates to Frequently Requested Changes" lang-team#200

**Link:** https://github.com/rust-lang/lang-team/pull/200

## RFCs waiting to be merged

None.

## Proposed FCPs

**Check your boxes!**
### "Edition Based Method Disambiguation: Preventing inference ambiguity breakages with extension trait methods" rfcs#3240

- **Link:** https://github.com/rust-lang/rfcs/pull/3240
- [**Tracking Comment**](https://github.com/rust-lang/rfcs/pull/3240#issuecomment-1377748067):
> Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:
>
> * [ ] @Amanieu
> * [ ] @BurntSushi
> * [ ] @dtolnay
> * [x] @joshtriplett
> * [ ] @m-ou-se
> * [ ] @nikomatsakis
> * [ ] @pnkfelix
> * [ ] @scottmcm
> * [ ] @tmandry
>
> 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](https://github.com/rust-lang/rfcbot-rs/blob/master/README.md) for info about what commands tagged team members can give me.
- [**Initiating Comment**](https://github.com/rust-lang/rfcs/pull/3240#issuecomment-1377748031):
> @rfcbot merge

### "unsafe attributes" rfcs#3325

- **Link:** https://github.com/rust-lang/rfcs/pull/3325
- [**Tracking Comment**](https://github.com/rust-lang/rfcs/pull/3325#issuecomment-1396911253):
> Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:
>
> * [x] @joshtriplett
> * [ ] @nikomatsakis
> * [ ] @pnkfelix
> * [ ] @scottmcm
> * [x] @tmandry
>
> 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](https://github.com/rust-lang/rfcbot-rs/blob/master/README.md) for info about what commands tagged team members can give me.
- [**Initiating Comment**](https://github.com/rust-lang/rfcs/pull/3325#issuecomment-1396911218):
> @rfcbot merge

scottmcm: Leans into discharging an obligation. Have talked about having separate words for introducing an obligation vs discharging one.

josh: Better to have that in a separate RFC.

Lokathor: Extern functions should also be unsafe, do we want to do that in the edition?

josh: Sounds reasonable. Needs a concrete proposal. You could, in an unsafe context, declare an extern function that would be callable from a safe context.

scottmcm: So the extern block needs to be `unsafe extern` and the function doesn't need to be `unsafe fn`.

josh: Exactly.

scottmcm: So please write the RFC :-)

josh: It would help us "sell" it to give people the (new) ability to declare safe extern functions.

pnkfelix: should lang#3325 (unsafe attributes) be on an edition boundary? Or does the spectre of UB motivate making the change on all editions?

scottmcm: I like the sound of doing it on an edition boundary.

pnkfelix: also, on subject of discharging: where is the discharge happening?

scottmcm/josh: the `no_mangle` introduces; the `unsafe` discharges here.

scottmcm: this doesn't exist, but imagine it's `unsafe attribute no_mangle;`, introducing the obligation that's later discharged in `#[(unsafe(no_mangle)]`.

pnkfelix: okay. because one could imagine further language changes that would enable discharge at a different scope (e.g an `unsafe crate` or `unsafe mod`, for example...)

scottmcm: I like the point about rolling out over an edition. The RFC should probably specify that

Lokathor: Do we want to encourage people to update to new editions?

josh: When it's as simple as a new keyword we should (`k#newkeyword`), but if it's much more complex than that we don't have to provide it in an old edition.

### "RFC: UTF-8 characters and escape codes in (byte) string literals" rfcs#3349

- **Link:** https://github.com/rust-lang/rfcs/pull/3349
- [**Tracking Comment**](https://github.com/rust-lang/rfcs/pull/3349#issuecomment-1396747916):
> Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:
>
> * [x] @joshtriplett
> * [ ] @nikomatsakis
> * [ ] @pnkfelix
> * [ ] @scottmcm
> * [ ] @tmandry
>
> Concerns:
>
> * raw-byte-strings-with-unicode (https://github.com/rust-lang/rfcs/pull/3349#issuecomment-1396747889)
>
> 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](https://github.com/rust-lang/rfcbot-rs/blob/master/README.md) for info about what commands tagged team members can give me.
- [**Initiating Comment**](https://github.com/rust-lang/rfcs/pull/3349#issuecomment-1396747889):
> I do think we should permit `br"¥¥¥"`, but I don't think we should make any of the other changes proposed in that table, for the reasons @m-ou-se stated.
>
> I'm going to go ahead and propose FCP for this. This does *not* preclude making further changes to how this information is presented.
>
> @rfcbot merge
>
> @rfcbot concern raw-byte-strings-with-unicode

### "Tracking issue for RFC 2515, "Permit impl Trait in type aliases"" rust#63063

- **Link:** https://github.com/rust-lang/rust/issues/63063
- [**Tracking Comment**](https://github.com/rust-lang/rust/issues/63063#issuecomment-1360043090):
> Team member @nikomatsakis has proposed to merge this. The next step is review by the rest of the tagged team members:
>
> * [x] @cramertj
> * [x] @joshtriplett
> * [x] @nikomatsakis
> * [ ] @pnkfelix
> * [ ] @scottmcm
>
> Concerns:
>
> * ~~~~ resolved by https://github.com/rust-lang/rust/issues/63063#issuecomment-1361432898
> * docs (https://github.com/rust-lang/rust/issues/63063#issuecomment-1364525286)
> * function-defining-uses (https://github.com/rust-lang/rust/issues/63063#issuecomment-1385946789)
>
> 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](https://github.com/rust-lang/rfcbot-rs/blob/master/README.md) for info about what commands tagged team members can give me.
- [**Initiating Comment**](https://github.com/rust-lang/rust/issues/63063#issuecomment-1360043060):
> @rfcbot fcp merge
>
> This has been a long-time coming. Let's Do This!
>
> [Stabilization report in this comment.](https://github.com/rust-lang/rust/issues/63063#issuecomment-1354392317)

https://github.com/rust-lang/rust/issues/107645

tmandry: Most flexible would be to restrict to items that mention the TAIT in their return types?

pnkfelix: Wonder why that wasn't mentioned.

scottmcm: FCP on this decision

pnkfelix: Will create a zulip thread to discuss more options.

tmandry: Can include the return type option there if you don't.

### "Tracking Issue for "C-unwind ABI", RFC 2945" rust#74990

- **Link:** https://github.com/rust-lang/rust/issues/74990
- [**Tracking Comment**](https://github.com/rust-lang/rust/issues/74990#issuecomment-1363474839):
> Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:
>
> * [x] @joshtriplett
> * [x] @nikomatsakis
> * [ ] @pnkfelix
> * [x] @scottmcm
> * [x] @tmandry
>
> Concerns:
>
> * docs (https://github.com/rust-lang/rust/issues/74990#issuecomment-1364528477)
>
> 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](https://github.com/rust-lang/rfcbot-rs/blob/master/README.md) for info about what commands tagged team members can give me.
- [**Initiating Comment**](https://github.com/rust-lang/rust/issues/74990#issuecomment-1363474832):
> Shall we stabilize the `extern "C-unwind"` and other `-unwind` calling conventions? This change will leave `extern "C"` unchanged for now, but have the existing feature gate continue to opt into the new behavior on nightly. We'll do a separate change later to make `extern "C"` and similar not permit unwinding.
>
> @rfcbot merge

tmandry: I'll look at my doc comments at least.

### "Stabilise inline_const" rust#104087

- **Link:** https://github.com/rust-lang/rust/pull/104087
- [**Tracking Comment**](https://github.com/rust-lang/rust/pull/104087#issuecomment-1350231887):
> Team member @scottmcm has proposed to merge this. The next step is review by the rest of the tagged team members:
>
> * [x] @cramertj
> * [x] @joshtriplett
> * [x] @nikomatsakis
> * [ ] @pnkfelix
> * [x] @scottmcm
>
> Concerns:
>
> * expectations-around-panics-in-inline-const (https://github.com/rust-lang/rust/pull/104087#issuecomment-1379582240)
> * post-monomorphization-errors (https://github.com/rust-lang/rust/pull/104087#issuecomment-1409927203)
> * should-unused-code-cause-errors (https://github.com/rust-lang/rust/pull/104087#issuecomment-1410921524)
>
> 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](https://github.com/rust-lang/rfcbot-rs/blob/master/README.md) for info about what commands tagged team members can give me.
- [**Initiating Comment**](https://github.com/rust-lang/rust/pull/104087#issuecomment-1350231871):
> Restarting the FCP from https://github.com/rust-lang/rust/pull/104087#issuecomment-1315946122
>
> @rfcbot fcp merge

### "Properly allow macro expanded `format_args` invocations to uses captures" rust#106505

- **Link:** https://github.com/rust-lang/rust/pull/106505
- [**Tracking Comment**](https://github.com/rust-lang/rust/pull/106505#issuecomment-1402511990):
> Team member @scottmcm has proposed to merge this. The next step is review by the rest of the tagged team members:
>
> * [x] @joshtriplett
> * [ ] @nikomatsakis
> * [ ] @pnkfelix
> * [x] @scottmcm
> * [ ] @tmandry
>
> Concerns:
>
> * ~~please-link-tests~~ resolved by https://github.com/rust-lang/rust/pull/106505#issuecomment-1416417520
>
> 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](https://github.com/rust-lang/rfcbot-rs/blob/master/README.md) for info about what commands tagged team members can give me.
- [**Initiating Comment**](https://github.com/rust-lang/rust/pull/106505#issuecomment-1402511930):
> We discussed this in the lang team meeting today. Broadly we thought that proc macros being able to emit tokens that use captures makes logical sense. Basically, a proc macro *emitting* something as a whole that one could write directly, as in https://github.com/rust-lang/rust/pull/106505/files#diff-868206cf54a88d81468a76d45e639cea40c537f2031d19f06c114e3cb329a426R44, seems entirely fine, though mixing things like `format!(concat!(…))` might still be best to reject.
>
> So I'll start a
>
> @rfcbot fcp merge
>
> but we had some requests to confirm, so...

### "Stabilize `anonymous_lifetime_in_impl_trait`" rust#107378

- **Link:** https://github.com/rust-lang/rust/pull/107378
- [**Tracking Comment**](https://github.com/rust-lang/rust/pull/107378#issuecomment-1430287200):
> Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:
>
> * [x] @joshtriplett
> * [ ] @nikomatsakis
> * [ ] @pnkfelix
> * [ ] @scottmcm
> * [ ] @tmandry
>
> 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](https://github.com/rust-lang/rfcbot-rs/blob/master/README.md) for info about what commands tagged team members can give me.
- [**Initiating Comment**](https://github.com/rust-lang/rust/pull/107378#issuecomment-1430287177):
> We discussed this in today's @rust-lang/lang meeting, and we think this is ready for an FCP to merge:
>
> @rfcbot merge
>
> We'd also like to make sure that future work on type-alias impl Trait (TAIT) doesn't automatically assume anonymous lifetimes will work there, and thinks carefully about how or if that should work.

## Active FCPs

None.

## P-critical issues

None.

## Nominated RFCs, PRs and issues discussed this meeting

### "lang agenda generator ignores lang-nominated closed issues" lang-team#199

**Link:** https://github.com/rust-lang/lang-team/issues/199

### "RFC: result_ffi_guarantees" rfcs#3391

**Link:** https://github.com/rust-lang/rfcs/pull/3391

scottmcm: Why is this not a layout guarantee?

Lokathor: ABI is separate from layout, but the RFC actually defines both of them.

Lokathor: Some questions around stability

josh: We document layout guarantees for Option (https://doc.rust-lang.org/std/option/#representation), not Result

scottmcm: "option-like" <https://rust-lang.github.io/unsafe-code-guidelines/layout/enums.html#discriminant-elision-on-option-like-enums>.

gary: https://github.com/rust-lang/rust/pull/60300 is FCP-ed by T-lang and covers all option-like

tmandry: Concerned about ZSTs becoming non-ZSTs, but `()` seems fine.

Lokathor: Sometimes crate authors will use a ZST for errors.

tmandry: Maybe `#[repr(transparent)]` can be used to mark it.

scottmcm: ZST, 1-alignment, ... . We have some issues about `repr(transparent)` getting this wrong, but it's all the same problems.

scottmcm: Seems like wanting a custom ZST is more valid for the E than the T side.

## Nominated RFCs, PRs and issues NOT discussed this meeting
### "RFC: Start working on a Rust specification" rfcs#3355

**Link:** https://github.com/rust-lang/rfcs/pull/3355

### "Introduce terminating scope for tail expressions of breakable scopes" rust#106493

**Link:** https://github.com/rust-lang/rust/pull/106493

### "TAIT defining scope options" rust#107645

**Link:** https://github.com/rust-lang/rust/issues/107645