All occurrences of Closure(<sig>) -> (T, !) with a structurally identical value-signature now share one inferred error-set node; every bare-! closure literal of that shape unions its escape tags in, and a `try slot(x)` against any matching-shape slot widens the caller's named set against that union. This closes the gap where a slot call (no static function name) skipped the widening check entirely. - shape_inferred_sets keyed by closureShapeKey (params + value-return via mangleTypeName, error slot excluded) so bare-!, non-failable, .function and .closure of one value-sig collapse to a single key. - convergeClosureShapeSets pre-pass (lowerRoot Pass 1d', after the name-keyed convergeInferredErrorSets): collectClosureShapes walks fn bodies through lambda boundaries; recordClosureShape resolves each concrete bare-! literal's shape and unions its raises (+ try named_fn() edges via calleeEscapeTags) into the shape node. - checkEscapeWidening falls back to shapeKeyOfCallee for bare-! slot calls (computed from the callee expr's .function/.closure type). Empty union is silently allowed (sub-feature 6). Scope: concrete shapes only (generic lambdas skipped); closure-to-closure try edges are not fix-pointed (under-approximation = a missed diagnostic, never a miscompile). Tests: 1041 (positive — union composes, runs), 1042 (reject — two widening diagnostics, exit 1).
2 B
2 B