# Libs Meeting 2025-02-19

###### tags: `Libs Meetings` `Minutes`

**Meeting Link**: https://meet.jit.si/rust-libs-meeting-ujepnbwg2lzqgt6wvrndwimi
**Attendees**: The 8472, Chris Denton, Josh Triplett, Mara

## Agenda

- Triage
- Anything else?

## Triage

### FCPs

3 rust-lang/rust T-libs FCPs

- merge rust.tf/115746 *Print thread ID in panic message* - (2 checkboxes left)
- merge rust.tf/132484 *unix: Relax escaping in `Debug` impl on `Command`* - (0 checkboxes left)
- merge rust.tf/133485 *[discussion][donotmerge]: Copy Python implementation for `float::div_euclid`* - (3 checkboxes left)

### (Prioritization Requested) rust.tf/137255 Panic-safety issue with `Zip` specializations

Marked as high priority.

The 8472 to fix it.

### (Nominated) rust.tf/135634 stop specializing on `Copy`

Lots of small regressions, some more than 1%: https://perf.rust-lang.org/compare.html?start=021fb9c09a19d206a37226fe6168f1cc7c984925&end=3e3177541887d784070e5ab17d5ce89fcef9b9cf&stat=instructions:u

The 8472: Maybe we should look at things that were previously specialized but are now no longer. Custom Copy impls? Needs some investigation.

The 8472: preference of t-types is to remove Copy specialization. we should continue to work on this. this is more regression than we usually accept unless critical. doesn't seem critical enough.

### (Nominated) rust.tf/137122 Specialize `Iterator::eq{_by}` for `TrustedLen` iterators

The 8472: Will eliminate some side-effects. Short-circuits if the lengths are unequal.

The 8472: In a different case, we cared about keeping side-effects. I think it's fine to skip the side effects here. It'd be weird to rely on the side effects of eq/eq_by.

Mara: Sounds good to me. Just do an FCP?

The 8472: Just TrustedLen? Or check for non-overlapping size ranges?

Mara: TrustedLen sounds enough for now.

The 8472 to start FCP.

### (Nominated) rust.tf/136842 Add libstd support for Trusty targets

Non-functional std except stdout and rand.

JoshT: We should not repeat the mistake of webassembly. (Everything compiles, nothing works.)

The 8472: This puts `#[cfg(not(target_os = "trusty"))]` outside `sys`. Don't we have a lint that forbids this? This shouldn't pass CI.

Mara: All the cfgs are inside `sys` or `os`. Those outside are just for tests. So, same situation as wasm.

The 8472: Having `Instant` is important. Will this target have that in the future?

From a github comment: They do want to add `Instant`, just haven't gotten around to it.

The 8472: Okay for tier 3 then, but no more?

JoshT: Seem acceptable. But long term we need a better solution for targets like this.

Mara: +1

consensus: accept this