Location-insensitive polonius: consider a loan escaping if an SCC has member constraints applied only #116960

lqd · 2023-10-19T22:02:10Z

The location-insensitive analysis considered loans to escape if there were member constraints, which makes some sense for scopes and matches the scopes that NLL computes on all the tests.

However, polonius and NLLs differ on the fuzzed case #116657, where an SCC has member constraints but no applied ones (and is kinda surprising). The existing UI tests with member constraints impacting scopes all have some constraint applied.

This PR changes the location-insensitive analysis to consider a loan to escape if there are applied member constraints, and for extra paranoia/insurance via fuzzing and crater: actually checks the constraint's min choice is indeed a universal region as we expect. (This could be turned into a debug_assert and early return as a slight optimization after these periods of verification)

The 4 UI tests where member constraints are meaningful for computing scopes still pass obviously, and this also fixes #116657.

r? @matthewjasper

matthewjasper · 2023-10-23T08:14:15Z

@bors r+

bors · 2023-10-23T08:14:17Z

📌 Commit d9c213c has been approved by matthewjasper

It is now in the queue for this repository.

…iaskrgr Rollup of 5 pull requests Successful merges: - rust-lang#116960 (Location-insensitive polonius: consider a loan escaping if an SCC has member constraints applied only) - rust-lang#116978 (Rewrite gdb pretty-printer registration) - rust-lang#117040 (coverage: Add UI tests for values accepted by `-Cinstrument-coverage`) - rust-lang#117064 (Eliminate rustc_attrs::builtin::handle_errors in favor of emitting errors directly) - rust-lang#117073 (Fix suggestion for renamed coroutines feature) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#116960 - lqd:applied-member-constraints-scope, r=matthewjasper Location-insensitive polonius: consider a loan escaping if an SCC has member constraints applied only The location-insensitive analysis considered loans to escape if there were member constraints, which makes *some* sense for scopes and matches the scopes that NLL computes on all the tests. However, polonius and NLLs differ on the fuzzed case rust-lang#116657, where an SCC has member constraints but no applied ones (and is kinda surprising). The existing UI tests with member constraints impacting scopes all have some constraint applied. This PR changes the location-insensitive analysis to consider a loan to escape if there are applied member constraints, and for extra paranoia/insurance via fuzzing and crater: actually checks the constraint's min choice is indeed a universal region as we expect. (This could be turned into a `debug_assert` and early return as a slight optimization after these periods of verification) The 4 UI tests where member constraints are meaningful for computing scopes still pass obviously, and this also fixes rust-lang#116657. r? `@matthewjasper`

lqd added 2 commits October 19, 2023 21:11

add non-regression test for issue 116657

8b76518

make applied_member_constraints accept an SCC instead of a region

c69bd94

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Oct 19, 2023

lqd added 2 commits October 20, 2023 20:59

consider a loan escapes the function via applied member constraints

fa45efa

slight Default cleanup for option

d9c213c

lqd force-pushed the applied-member-constraints-scope branch from d4a006e to d9c213c Compare October 20, 2023 21:00

lqd marked this pull request as ready for review October 20, 2023 21:07

rustbot assigned matthewjasper Oct 20, 2023

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 23, 2023

aliemjay approved these changes Oct 23, 2023

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matthiaskrgr mentioned this pull request Oct 23, 2023

Rollup of 5 pull requests #117087

Merged

bors merged commit 726709b into rust-lang:master Oct 23, 2023
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rustbot added this to the 1.75.0 milestone Oct 23, 2023

lqd deleted the applied-member-constraints-scope branch October 23, 2023 19:55

github-actions bot mentioned this pull request Oct 31, 2023

Automated pull from upstream master ferrocene/ferrocene#74

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Location-insensitive polonius: consider a loan escaping if an SCC has member constraints applied only #116960

Location-insensitive polonius: consider a loan escaping if an SCC has member constraints applied only #116960

lqd commented Oct 19, 2023 •

edited

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matthewjasper commented Oct 23, 2023

bors commented Oct 23, 2023

Location-insensitive polonius: consider a loan escaping if an SCC has member constraints applied only #116960

Location-insensitive polonius: consider a loan escaping if an SCC has member constraints applied only #116960

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lqd commented Oct 19, 2023 • edited Loading

matthewjasper commented Oct 23, 2023

bors commented Oct 23, 2023

lqd commented Oct 19, 2023 •

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