---
# System prepended metadata

title: Libs Meeting 2025-04-23
tags: [Minutes, Libs Meetings]

---

# Libs Meeting 2025-04-23

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

**Meeting Link**: https://meet.jit.si/rust-libs-meeting-ujepnbwg2lzqgt6wvrndwimi
**Attendees**: Amanieu, JoshS, JoshT, The 8472, Chris Denton, Mara, Sarah Quiñones, Urgau

## Agenda

- Triage
- Anything else?

## Triage

### FCPs

4 rust-lang/rust T-libs FCPs

  - merge rust.tf/115746 *Print thread ID in panic message* - (2 checkboxes left)
  - merge rust.tf/137122 *Specialize \`Iterator::eq{\_by}\` for \`TrustedLen\` iterators* - (3 checkboxes left)
  - merge rust.tf/132484 *unix: Relax escaping in \`Debug\` impl on \`Command\`* - (0 checkboxes left)
  - merge rust.tf/135634 *stop specializing on \`Copy\`* - (4 checkboxes left)

[m-ou-se (2)](https://rfcbot.rs/fcp/m-ou-se), [cuviper (1)](https://rfcbot.rs/fcp/cuviper), [the8472 (1)](https://rfcbot.rs/fcp/the8472), [joshtriplett (3)](https://rfcbot.rs/fcp/joshtriplett), [Amanieu (1)](https://rfcbot.rs/fcp/Amanieu), [thomcc (1)](https://rfcbot.rs/fcp/thomcc)


### (Backports) rust.tf/139624 *Don't allow flattened format\_args in const.*

Accepted.

### (Prioritization Requested) rust.tf/140020 *regression: \`error\[E0308\]: mismatched types\` for \`is\_multiple\_of\`*

As usual: New method vs extension trait in the ecosystem.

Integer trait uses everything by reference. Our new method takes things by copy. Makes sense.

JoshS: We should just acknowledge and accept.

Amanieu: 1000 downloads per month, 9000 downloads per month, ..

JoshS: This should've been warnings, right? The compiler does that?

Amanieu: not sure


### (Nominated) rust.tf/140042 *Library team consensus on promoting tier 3 riscv32 ESP\-IDF targets to tier 2 with std that has processes and signals support stubbed out*

JoshT: One of the most stubbed-out targets, other than wasm. It's not just processes and signals.

JoshT: Probably still acceptable..

The 8472: We consider wasm a mistake, though.

The 8472: It is not unix but tries to be?

Amanieu: it has a libc with unix-like apis. it's re-using unix pthreads, filesystem stuff, etc.

The 8472: how about cfg(unix)?

Amanieu: no, it is not cfg(unix).

JoshT: It uses some of the files from sys/unix, but that's internal.

The 8472: that's fine. should not be cfg(unix)

Amanieu: should double check that.

Amanieu: Oh, it is!

JoshT: It does not support processes, but it does support threads?

Amanieu: correct

JoshT: getcwd() always gives "/". chdir() is always unsupported. the kind of thing that makes me stare

JoshT: why does it claim to have that in its libc, rather than just not having that build?

Amanieu: presumably to make it work for programs that don't call it?

Amanieu: Or at the rust level?

Amanieu: we consider it acceptable for any syscall to fail. cfg() would be unportable.

JoshT: seems like the same mistake as with wasm.

Amanieu: problem with wasm is things that don't return Result, like time stuff, and then panic. Not the things that can return Result, and always fail.

Mara: cfg(unix) sounds like posix compliance to me. not the case here, right?

JoshT: is it mostly posix-compliant except exec() etc? or is it more severe?

Amanieu: by some standard, windows is mostly posix-compliant. windows is more unix than this.

Amanieu: emscripten is unix, but wasi is not.

JoshS: emscripten comes with a whole bunch of unix things.

JoshS: might not be our (libs) decision. could be lang or compiler

JoshT to write up a summary of our discussion.

### (Waiting on team) rust.tf/134536 *Lint on fn pointers comparisons in external macros*

### (Regressions) rust.tf/119560 *\`cargo test\` performance regression on Windows on version 1.75.0*

### (Regressions) rust.tf/137971 `P-high` *ReFS volumes on Windows Server 2022 break compilation*

Amanieu: fix in progress

Waiting on author

### (Regressions) rust.tf/139730 `P-high` *A case of compound x86\_64 performance regression caused by LLVM 20 and #124810*

### (Regressions) rust.tf/139542 *Type inference regression in 1.86 stable, due to unstable ByteStr*

### (Regressions) rust.tf/53340 *Performance regression in tight loop since rust 1.25*

### (Regressions) rust.tf/112180 *assertion failed: key as usize != KEY\_SENTVAL in DragonFly BSD*

### (Regressions) rust.tf/124216 `P-medium` *Performance regression: rustc failed to optimize specific x86\-64 SIMD intrinsics after 1.75.0*

### (Regressions) rust.tf/138054 `P-low` *unreachable pub item from portable\-simd with target\_feature = "avx512f"*

### (Regressions) rust.tf/130320 `P-medium` *stdlib code size increase in nightly\-2024\-09\-01 for aarch64\-linux\-android*


## Actions

- [ ] Reply to all issues/PRs discussed in this meeting, or add them to the [open action items](https://hackmd.io/Uehlc0qUQfWfvY1swYWRgQ).

_Generated by [fully-automatic-rust-libs-team-triage-meeting-agenda-generator](https://github.com/rust-lang/libs-team/tree/main/tools/agenda-generator)_
