Add meeting notes for 2019/05/14

Author: lqd

working-groups/polonius/minutes/2019.05.14-meeting.md

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+# WG-Polonius meeting minutes: 2019/05/14
+---
+
+Relevant links:
+- The meeting happened in this [Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/186049-t-compiler.2Fwg-polonius/topic/meeting.202019.2E05.2E14).
+- The [WIP Roadmap](https://paper.dropbox.com/doc/Polonius-Roadmap--AY6C806s~AZK~e7wagmys2_wAg-hk3a9ynduUN2gk1A0NNTF) Paper.
+
+---
+
+A recap of last week's work:
+- [Niko] and [Albin] went through a lot of details of liveness, in the dedicated Zulip thread ([around this point](https://rust-lang.zulipchat.com/#narrow/stream/186049-t-compiler.2Fwg-polonius/topic/liveness.20polonius.23104/near/165238306)). 
+- With the previous week's steps, and these conversations, [Albin] has continued the work on liveness, and is now _basically done_ :tada:. With the 2 PRs, Polonius is able to compute the same `region_live_at` facts as rustc. The remaining work being mostly clean-up, various minor fixes, more testing, and finally, reviews. The remaining tasks are listed in [this comment](https://github.com/rust-lang/polonius/issues/104#issuecomment-492380520).
+- [Rémy] has continued looking at the rustc test suite under Polonius. As expected, over [#60171](https://github.com/rust-lang/rust/pull/60171), there are less than 20 failures. A first pass at analyzing the results is available [here](https://hackmd.io/CjYB0fs4Q9CweyeTdKWyEg) with links to the necessary information (test source, NLL/polonius outputs, diff) to categorize the failures but the TL;DR is: some of them are trivially fixable (being artifacts of test construction, and identical under NLLs and Polonius), some are duplicates or similar to of other failures, a lot are simply different diagnostics, and a handful need more in-depth investigation to understand the difference in behaviour, if it's a bug, and so on. More information will generally be available in [the dedicated thread](https://rust-lang.zulipchat.com/#narrow/stream/186049-t-compiler.2Fwg-polonius/topic/rustc.20compare-mode.20polonius).
+- [@lokalmatador] is working through profiling tasks and may soon be able to gather benchmark data.
+- On the more administrative side of things, [Rémy] wrote up the meeting notes from the previous weeks, updated the roadmap to [add testing and validation](https://paper.dropbox.com/doc/Polonius-Roadmap--AdKXqkTdIxkM3zh3xZmuZ4RmAg-hk3a9ynduUN2gk1A0NNTF#:uid=569313235802426695258068&h2=Extending-Polonius-to-cover-th), as we mentioned during last week's meeting.
+
+Useful information:
+- various members will be absent at different points in the upcoming weeks. There may not necessarily be a meeting sometimes (TBD), but async updates will be available on Zulip in any case.
+
+Useful future tasks we mentioned:
+- with the liveness work about to land, we mentioned some important optimizations rustc has about liveness (in particular, trying to _avoid_ computing it unless it is necessary), and that Polonius (or its inputs) will surely need as well. This topic was discussed at [this point in the meeting thread](https://rust-lang.zulipchat.com/#narrow/stream/186049-t-compiler.2Fwg-polonius/topic/meeting.202019.2E05.2E14/near/165653374).
+
+----
+For the following week:
+- [Albin] will tackle the remaining final liveness.
+- [Rémy] will continue on the rustc test suite results (fix the trivial differences, etc) and time permitting, help with the final liveness tasks.
+- [@lokalmatador] will continue their benchmarking endeavour.
+
+[Albin]: https://github.com/albins
+[Niko]: https://github.com/nikomatsakis
+[Rémy]: https://github.com/lqd
+[@lokalmatador]: https://github.com/lokalmatador