---
# System prepended metadata

title: Libs Meeting 2024-04-03
tags: [Minutes, Libs Meetings]

---

# Libs Meeting 2024-04-03

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

**Meeting Link**: https://meet.jit.si/rust-libs-meeting-ujepnbwg2lzqgt6wvrndwimi
**Attendees**: Amanieu, Josh Triplett, The 847, Chris Denton, Mara

## Agenda

- Triage
- Anything else?

## Triage

### FCPs

1 rust-lang/rust T-libs FCPs

  - merge rust.tf/115746 *Print thread ID in panic message if thread name is unknown* - (3 checkboxes left)

[m-ou-se (1)](https://rfcbot.rs/fcp/m-ou-se), [the8472 (1)](https://rfcbot.rs/fcp/the8472), [joshtriplett (1)](https://rfcbot.rs/fcp/joshtriplett)

### (Critical) rust.tf/122857 `P-critical` *No backtrace on windows with current rustc stable*

Worked around in 1.77.1 released a few days ago. No longer critical?

Removed libs label, leave it to the compiler team.

### (Backports) rust.tf/122396 *Less generic code for Vec allocations*

Very small improvement. Not worth backporting. Beta rejected.

### (Backports) rust.tf/123057 *unix fs: Make hurd using explicit new rather than From*

Beta accepted.

### (Prioritization Requested) rust.tf/123369 *\`VecDeque::shrink\_to\` leads to UB if \`handle\_alloc\_error\` unwinds.*

Medium priority because it's only on nightly.

### (Nominated) rust.tf/122268 *Link MSVC default lib in core*

Amanieu: Question is whether no_std can assume the system libs are available? I want to argue: yes

The 8472: What if someone wants to build sandboxed code that will run in a very restricted environment?

Josh: Then it should probably use the -none target

The 8472: Do we have those? And do they have a matching ABI?

Amanieu: I think we have them as tier 3

The 8472: We need a definition of what no_std means. We should collect use cases and find a good definition.

Mara: We need RFRs: Request For Research.

For this particular PR: Merge and continue.

### (Waiting on team) rust.tf/122661 *Assert that the first \`assert!\` expression is \`bool\`*

Mara: Discussed this in libs-api yesterday, but we forgot to consider &bool

Josh: Seems reasonable to accept &bool

Josh: Might be worth crater'ing

Conclusion: try crater first, then talk more.

### (Regressions) rust.tf/123285 *regression: unsafe precondition(s) violated: slice::get\_unchecked\_mut requires that the index is within the slice*

Just detecting UB. Nothing to do; won't fix.
