Prototype of Polonius

[nikomatsakis]

[lqd]

Status on roadmap/WG/location-insensitive prototype:

• up-to-date roadmap published
• location-insensitive analysis landed in rustc, with empirical evaluation that this is equivalent to NLLs until a-mir-formality formalism is available:
  • differential testing via tests, fuzzing, and crater: asserting no differences in scopes compared to NLLs'
  • fuzzing: has uncovered 2 issues, now fixed
  • crater runs:
    • first run uncovered a difference on 10 crates, same root cause
    • fix PR landed, clean results on second run
• various cleanups of borrowck, NLLs, and legacy polonius have landed
• onboarding Amanda, starting with higher-ranked task from the roadmap
• no new progress on borrowck/polonius in a-mir-formality just yet on our side, but there are plans in ralf's team
• moving on to location-sensitivity

Current status on location-sensitive prototype:

• the most up-to-date details about future prototyping are in this hackmd, and evolved out of the two previous descriptions
• we've started looking into realizing this design in-tree, but it's still early days