Libs Meeting 2021-03-03/04

# Libs Meeting 2021-03-03/04 ###### tags: `Libs Meetings` `Minutes` **Attendees**: Jane, JoshTriplett, sfackler, dtolnay, Amanieu, djc, Mara ## Agenda - [Open action items](https://hackmd.io/ovrbJj6CRduRgSA0Wzg2zg) - New prelude - [RFC 3090](https://github.com/rust-lang/rfcs/pull/3090) - Some small changes for edition 2021. - More changes for all editions. Lots of bikeshedding. Needs a more general policy. - Summary of comments [here](https://github.com/rust-lang/rfcs/pull/3090#issuecomment-789816556) - Implementation for edition-specific preludes: [[82217](https://github.com/rust-lang/rust/pull/82217)] (open) - Lots of feedback on [[62633](https://github.com/rust-lang/rust/issues/62633)] (Option::expect\_none and unwrap\_none), disagreeing with our FCP to close - Copy `Range` types - Additional types vs making current types `Copy` with `#[must_clone]` - Additional types proposal from sfackler: [[hackmd](https://hackmd.io/cM22mZ5JRH2RAdSART8bWQ)] - Naming new types is hard. [`#[rustc_per_edition]` aliases](https://github.com/rust-lang/rust/pull/82489) could work, but not sure if we should. - `#[must_clone]` / `MustClone`: See [eddyb's comment](https://github.com/rust-lang/rfcs/issues/2848#issuecomment-697257283) and [their experimental implementation](https://github.com/rust-lang/rust/pull/77180) - `IntoIterator` for arrays - PR: [65819](https://github.com/rust-lang/rust/pull/65819) - Has been stuck forever. Not clear how to continue. Can the new edition help? - Triage - Anything else? ## Triage ### FCPs 2 open T-libs FCPs: <details><summary><a href="https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-libs+label%3Aproposed-final-comment-period">2 <code>rust-lang/rust</code> FCPs</a></summary> - [[merge 81050](https://github.com/rust-lang/rust/issues/81050#issuecomment-765341798)] *Stabilize core::task::ready!* - (2 checkboxes left) - [[merge 77704](https://github.com/rust-lang/rust/issues/77704#issuecomment-760056634)] *Implement indexing slices with pairs of core::ops::Bound<usize>* - (2 checkboxes left) </details> <p></p> [Amanieu (1)](https://rfcbot.rs/fcp/Amanieu), [BurntSushi (2)](https://rfcbot.rs/fcp/BurntSushi), [KodrAus (0)](https://rfcbot.rs/fcp/KodrAus), [dtolnay (0)](https://rfcbot.rs/fcp/dtolnay), [joshtriplett (0)](https://rfcbot.rs/fcp/joshtriplett), [m-ou-se (1)](https://rfcbot.rs/fcp/m-ou-se), [sfackler (0)](https://rfcbot.rs/fcp/sfackler) ### Nominated - [2 `rust-lang/rfcs` items](https://github.com/rust-lang/rfcs/issues?q=is%3Aopen+label%3AT-libs+label%3AI-nominated) - [[2979](https://github.com/rust-lang/rfcs/pull/2979)] *\[RFC\]: Libs Team Governance* - [[3090](https://github.com/rust-lang/rfcs/pull/3090)] *A new prelude for the 2021 edition* - [5 `rust-lang/rust` items](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-libs+label%3AI-nominated) - [[54140](https://github.com/rust-lang/rust/issues/54140)] *Tracking Issue: Procedural Macro Diagnostics (RFC 1566)* - [[80149](https://github.com/rust-lang/rust/pull/80149)] *Use getrandom for generating HashMap seed* - [[82664](https://github.com/rust-lang/rust/issues/82664)] *regression: reduce on iterator conflicts* - [[82665](https://github.com/rust-lang/rust/issues/82665)] *regression: AsRef inference breakage* - [[82666](https://github.com/rust-lang/rust/issues/82666)] *regression: unsigned\_abs inherent method conflict* ### Waiting on team - [0 `rust-lang/rfcs` items](https://github.com/rust-lang/rfcs/issues?q=is%3Aopen+label%3AT-libs+label%3AS-waiting-on-team) - [4 `rust-lang/rust` items](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-libs+label%3AS-waiting-on-team) - [[62633](https://github.com/rust-lang/rust/issues/62633)] *Tracking issue for Option::expect\_none(msg) and unwrap\_none()* FCP finished. Should be closed? - [[76901](https://github.com/rust-lang/rust/pull/76901)] *Implement RFC 2500 Needle API (Part 1)* - [[80771](https://github.com/rust-lang/rust/pull/80771)] *Make NonNull::as\_ref (and friends) return refs with unbound lifetimes* - [[81989](https://github.com/rust-lang/rust/pull/81989)] *Add doc aliases for python and Java collections* - We may need a general decision here: what criteria do we want to use for adding aliases based on other languages? Proposal: "Popular language, reasonably common function (not an obscure one), unambiguous mapping for what the search should lead to" ### Needs decision - [10 `rust-lang/rust` items](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-libs+label%3AI-needs-decision) - [[25053](https://github.com/rust-lang/rust/issues/25053)] *UnsafeCell should implement the Copy trait* - [[26951](https://github.com/rust-lang/rust/issues/26951)] *Abort on some large allocation requests, Panic on other* - [[29494](https://github.com/rust-lang/rust/issues/29494)] *Command does not escape arguments as expected on windows* - [[37868](https://github.com/rust-lang/rust/issues/37868)] *std::process::Command's current\_dir behaves differently on Unix and Windows, with respect to relative exe paths* - [[42412](https://github.com/rust-lang/rust/issues/42412)] *Incorporate @raphlinus' container cheat sheet into the std::collections module docs* - [[56889](https://github.com/rust-lang/rust/issues/56889)] *Write::write\_all erroring when encountering Ok(0) interacts poorly with the contract of Write::write* - [[59878](https://github.com/rust-lang/rust/issues/59878)] *Box\<\[T\]\> should have an IntoIter implementation.* - Backwards-compatibility issue. Could introduce in the future with a transition/edition, and if so, would need a future compatibility lint. - [[62726](https://github.com/rust-lang/rust/issues/62726)] *Tracking issue for io\_slice\_advance* - [[79490](https://github.com/rust-lang/rust/issues/79490)] *Whether floating point value Display should adhere to IEEE standard?* - Josh: :+1:, can we do a quick consensus check on this? - [[80823](https://github.com/rust-lang/rust/pull/80823)] *Add Cow::disown\_if() and Cow::disown\_if\_eq()* - Josh: Seems fine other than naming ## Notes Prelude - Crater run TryInto/TryFrom - djc to send PR for crater - FromIterator has some use cases over .collect() for e.g. HashMap. - Probably no breakage in the ecosystem. Try in the same crater run. - djc to check with compiler team about migration lints - `drop` was originally only in the prelude because because there was no better module for it yet. - dtolnay: names in the prelude are things that we wouldn't want people to define in their own crates (e.g. Box, but not Mutex or File (people might want an async File)). - Proposed guideline (not a hard requirement): "It would be shocking for the unqualified name to refer to anything other than the std version" - sfackler: Read/Write could maybe use 'inherent trait impls' - a new language feature/attribute/thing. Lang team seems in favour of this idea. But no concrete proposal yet. - Mara to write comment expect_none/unwrap_none - No new evidence/arguments provided since the previous consensus - joshtriplett: err_or().unwrap()? (err_or doesn't exist yet) - Mara to write comment Range: - InclusiveRange contains a flag, so wouldn't be the right type for the `Copy` version. So that's not solved with `MustClone`. - Rename `Range*` to `Range*Iter`? Edition-specific aliases could work. Lots of implementation work (rustdoc etc.) - `Interval` for the `Copy` name? - rustfix needs a state that works in both the old and new edition. `Range::new(..)`? `(a..b).into_iter()`? - sfackler to update RFC IntoIter for arrays: - Maybe over the edition? Niko said he'd think about it. - another crater run? Regressions: - Seems acceptable. ## Actions - [x] Reply to all issues/PRs discussed in this meeting, or add them to the [open action items](https://hackmd.io/ovrbJj6CRduRgSA0Wzg2zg).