# Libs Meeting 2023-06-07
###### tags: `Libs Meetings` `Minutes`
**Meeting Link**: https://meet.jit.si/rust-libs-meeting-ujepnbwg2lzqgt6wvrndwimi
**Attendees**: Amanieu, The 8472, Mara, joboet
## Agenda
- Triage
- Anything else?
## Triage
### FCPs
1 rust-lang/rust T-libs FCPs
- merge rust.tf/104385 *Raise minimum supported Apple OS versions* - (9 checkboxes left)
### (Backports) rust.tf/112292 *Avoid unwind across \`extern "C"\` in \`thread\_local::fast\_local\`*
This 'technically UB' doesn't really result in actual issues, it seems.
Not a recent regression, so might not be a good backport candidate.
Left a comment.
### (Nominated) rust.tf/84187 *Tracking Issue for restructuring \`sys\_common\`*
Discussed last time. Still need to respond. Mara to respond.
### (Nominated) rust.tf/110708 *Consider documenting that (parts of?) stdlib must not be used before/after main*
Discussed last time. Amanieu replied, saying the main issue is thread::current(), which is only used in a few places.
For LocalKey::with we already document it: https://doc.rust-lang.org/stable/std/thread/struct.LocalKey.html#method.with
(And also have a try_with.)
Only for thread::current() (and a few APIs that use that) we don't provide any panic docs (or a try_current() etc.).
Pre-main seems like it's rarely a problem, it's post-main that is more interesting.
### (Nominated) rust.tf/111071 *assert\_eq! message format (take 2a)*
Summary: https://github.com/rust-lang/rust/pull/111071#issuecomment-1576734594
Question 1: Change the default panic handler output format?
Possible answers:
1. No
2. Yes, as proposed, but only for multi-line messages
3. Yes, as proposed, but for all messages
3 seems like a nice option, because the current "at {message}, {location}" feels flipped/swapped.
Crater run could check how widely people depend on the exact output.
We can do an FCP to make it show up in TWiR.
Split this into a separate PR to focus first on just the panic_handler output, independent from assert_eq.
Question 2: Change the panic message of assert_eq?
- Put the message on a separate line?
- Call it "error" or "message" or "description" or ... ?
- Put message on the first line?
```
assertion failed: `left == right`
error: message goes here
left: `1`
right: `2`
```
```
assertion failed: `left == right`, message goes here
left: `1`
right: `2`
```
```
assertion failed: message goes here
check: left == right
left: 1
right: 2
```
Leave this for after the PR for question 1.
### (Waiting on team) rust.tf/103126 *Add cfg(no\_128\_bit) to core: removes u128/i128 formatting*
Discussed and responded last time. FCP close in progress. Removed label.
### (Regressions) rust.tf/109064 `P-high` *\`+outline\-atomics\` violates "core shall not depend on libc"*
Resolutions: Either:
- remove outline-atomics, or
- allow core to depend on libc.
The 'can core depend on libc' discussion is a complicated one, probably needs an RFC for a resolution.
Amanieu to write up that RFC.
### (Regressions) rust.tf/112180 *assertion failed: key as usize != KEY\_SENTVAL in DragonFly BSD*
Might have already been broken but simply not resulted in a panic.
Tier 3, so not high priority.