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Merge pull request #36 from davidtwco/nll-working-group-template
Update NLL working group to match template.
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‎working-groups/.template/README.md

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Other NLL labels also exist:
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- [**NLL-fixed-by-NLL**][NLL_fixed-by-NLL] labels bugs that are problems solely with the
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- [**NLL-fixed-by-NLL**][NLL-fixed-by-NLL] labels bugs that are problems solely with the
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AST-borrowck -- they are bugs that we intend to close once everyone migrates over to NLL.
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- [**NLL-polonius**][NLL-polonius] labels bugs related to the Polonius subproject - see the
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Polonius working group for more information on these.

‎working-groups/nll/FAQ.md

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# Frequently asked questions
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## What is NLL?
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XXX
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## What is "migration mode"?
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XXX
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# Frequently Asked Questions (FAQ)
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If you have a question, feel free to file an issue or ask in the working group's Zulip stream.
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## What is the relationship to Polonius?
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Polonius is an experimental, "next generation" NLL implementation,
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initially described in [this blog post][polonius]. Enabling the use of
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Polonius is **not** in scope for the NLL working group -- there will
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be a dedicated working group exploring that topic.
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Polonius is an experimental, "next generation" NLL implementation, initially described in
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[this blog post][polonius]. Enabling the use of Polonius is **not** in scope for the NLL working
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group -- see [the polonius working group][../polonius].

‎working-groups/nll/NOTES.md

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Feburary 19, 2019
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# Non-Lexical Lifetimes (NLL) Meeting Notes
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This document contains meeting notes from the NLL working group.
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## 2019-02-19:
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- Agenda:
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- Meta: What should this meeting be for?
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- Sync-up regarding Place 2.0 ([#52708][])
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- Status Updates (TBD)
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February 13, 2019
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## 2019-02-13:
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- Status updates
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- matthewjasper
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- Opened [#58347][] to fix issues around closures

‎working-groups/nll/README.md

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# Scope and purpose
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# Non-Lexical Lifetimes (NLL) Working Group
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![working group status: winding down][status]
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The **nll** working group is working towards transitioning the
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compiler use a MIR-based borrow check that implements the initial
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non-lexical lifetimes proposal.
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This working group aims to implement non-lexical lifetimes (NLL), as described in RFC 2094:
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XXX add links to RFCs etc
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> Extend Rust's borrow system to support non-lexical lifetimes -- these are lifetimes that are
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> based on the control-flow graph, rather than lexical scopes. The RFC describes in detail how
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> to infer these new, more flexible regions, and also describes how to adjust our error messages.
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> The RFC also describes a few other extensions to the borrow checker, the total effect of which is
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> to eliminate many common cases where small, function-local code modifications would be required
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> to pass the borrow check.
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# Current status
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- **Leads:** [@nikomatsakis][nikomatsakis] and [@pnkfelix][pnkfelix]
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- **Meeting Notes:** [All](NOTES.md)
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NLL has **landed** in the Rust 2018 edition and is currently in
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**migration** mode. The working group is currently working towards
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enabling NLL by default, for all editions, and in the full,
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non-migration mode. XXX say more here
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[status]: https://img.shields.io/badge/status-winding%20down-orange.svg?style=for-the-badge
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# How to participate
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## Status
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NLL has **landed** in the Rust 2018 edition and is currently in **migration** mode. The working
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group is currently working towards enabling NLL by default, for all editions, and in the full,
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non-migration mode.
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## Chat forum
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## What is the goal of this working group?
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This working group aims to accomplish the following:
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On [the rust-lang Zulip][z], in [the `#t-compiler/wg-nll` stream][s].
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- Implement a new borrow checker based on the MIR that supports non-lexical lifetimes.
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- Handle the migration from the existing AST-based borrow checker.
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[z]: https://rust-lang.zulipchat.com/
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[s]: https://rust-lang.zulipchat.com/#narrow/stream/122657-t-compiler.2Fwg-nll
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# How can I get involved?
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If you are interested in getting involved in this working group, you should try to attend a meeting and
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introduce yourself or send a message in the Zulip stream. You can be added to the GitHub and Zulip
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group for the working group if you are interested in being pinged when there are available tasks.
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## Weekly triage meeting
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- **Desired experience level:** Any
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- **Relevant repositories:** [`rust-lang/rust`][repo] (specifically `src/librustc_mir/borrow_check`)
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- **Zulip stream:** [`#t-compiler/wg-nll`][zulip] on Zulip
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There is a weekly triage meeting on Wednesdays at 15:30pm Boston time
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(UTC-05:00 presently). This meeting takes place on [Zulip][z] in a
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dedicated topic of the [the `#t-compiler/wg-nll` stream][s].
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[repo]: https://github.com/rust-lang/rust
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[zulip]: https://rust-lang.zulipchat.com/#narrow/stream/122657-t-compiler.2Fwg-nll
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## What if I don't have much time?
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If you don't have time to contribute code, consider using `#![feature(nll)]` to help find bugs
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with NLL. If you do, we'd love it if you could file an issue.
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## Are there any resources so I can get up to speed?
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There are some resources available for those interested in contributing to get some background
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and context:
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- MIR is an intermediate representation used within the compiler. NLL is implemented as a new
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borrow checker implemented on the MIR. You can read about the MIR in
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the [relevant rustc-guide chapter](https://rust-lang.github.io/rustc-guide/mir/index.html).
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- You can read about the major phases and internals of the MIR borrow checker in
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it's [rustc-guide chapter](https://rust-lang.github.io/rustc-guide/borrow_check.html).
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- NLL was originally specified
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in [RFC 2094](https://github.com/rust-lang/rfcs/blob/master/text/2094-nll.md).
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- [@nikomatsakis][nikomatsakis]'s blog posts on NLL are also useful for getting familiar with the
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goals of NLL and some initial implementation ideas.
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* [Introduction][introduction], [NLL based on liveness][liveness] and
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[NLL adding the outlives relation][outlives].
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[introduction]: http://smallcultfollowing.com/babysteps/blog/2016/04/27/non-lexical-lifetimes-introduction/
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[liveness]: http://smallcultfollowing.com/babysteps/blog/2016/05/04/non-lexical-lifetimes-based-on-liveness/
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[outlives]: http://smallcultfollowing.com/babysteps/blog/2016/05/09/non-lexical-lifetimes-adding-the-outlives-relation/
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## Do I need to attend any meetings?
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The NLL working group meets regularly for triage and discussion of high priority issues - see
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the [compiler team meeting calendar](../README.md#meeting-calendar) for the most up to date
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time. Attendance is not mandatory but recommended as this can be a good opportunity to ask any
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questions and find new issues to work on.
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## What do all these NLL labels mean?
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The NLL working group monitors the [**A-NLL**][A-NLL] label for issues relating to NLL.
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The follow extra labels are used during the working group's prioritization and triage, in roughly
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priority order:
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- [**NLL-sound**][NLL-sound] labels bugs around examples of code that is meant to be rejected by
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NLL. Usually such bugs are either ICE'ing or being erroneously accepted by NLL. *NLL-sound*
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things tend to be higher priority than *NLL-complete* things, at least at the moment.
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- [**NLL-performant**][NLL-performant] is for cases where NLL is causing *slow, slow, slow*
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compile times.
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- [**NLL-complete**][NLL-complete] labels bugs around examples of code that is meant to be
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accepted by NLL. Usually such bugs are either ICE'ing or being erroneously rejected by NLL.
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- [**NLL-reference**][NLL-reference] labels any issues relating to documenting NLL's behaviour
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into the language reference.
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- [**NLL-diagnostics**][NLL-diagnostics] labels cases where the diagnostics emitted by NLL
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specifcally needs improvement. Usually it is/was used for cases where NLL is a regresion
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w.r.t diagnostics when compared to AST-borrowck (but at this point its really more of a
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catch-all for any diagnostic issue originating from the NLL code base).
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Other NLL labels also exist:
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- [**NLL-fixed-by-NLL**][NLL-fixed-by-NLL] labels bugs that are problems solely with the
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AST-borrowck -- they are bugs that we intend to close once everyone migrates over to NLL.
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- [**NLL-polonius**][NLL-polonius] labels bugs related to the Polonius subproject - see the
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Polonius working group for more information on these.
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[A-NLL]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3AA-NLL
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[NLL-sound]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3ANLL-sound
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[NLL-performant]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3ANLL-performant
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[NLL-complete]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3ANLL-complete
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[NLL-reference]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3ANLL-reference
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[NLL-diagnostics]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3ANLL-diagnostics
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[NLL-fixed-by-NLL]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3ANLL-fixed-by-NLL
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[NLL-polonius]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3ANLL-polonius
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[nikomatsakis]: https://github.com/nikomatsakis
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[pnkfelix]: https://github.com/pnkfelix

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