FA-42904 / Borrow checking / Member archive

Combined use lifetime drops points from one use region · case 04

Combined use lifetime drops points from one use region.

Member previewVariant 4 · 3 implementations · 17 checks per implementation

Case contract

Finite lexical regions map names to sets of program-point integers. Longer region contains every point of shorter. Queries: outlives(a,b), meet(a,b), join(a,b), missing(a,b), strict(a,b), eq(a,b), disjoint(a,b), covers(a, list-of-regions), gap(a,b,c) requires a cover intersection of b,c, and choose(a,candidates) returns lexically sorted candidate regions containing a with smallest cardinality, ties lexical. Return booleans or sorted lists as appropriate.

Why this case matters

A finite offline static-analysis model of ownership and borrowing; it does not execute the analyzed program.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
join	`[5]`	`[4, 5, 6]`	Failed

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