Result: done
Files: crates/nikaia-std/src/tools/check_core_flow.nika crates/nikaia-std/src/tools/check_facts.nika crates/nikaia-std/src/tools/emit_core_match.nika crates/nikaia-std/src/tools/lowered/check_core_flow.rs crates/nikaia-std/src/tools/lowered/check_facts.rs crates/nikaia-std/src/tools/lowered/emit_core_match.rs tests/compiler/tests/a_narrowed_field_in_an_or_pattern.nika tests/compiler/tests/a_narrowed_field_in_an_or_pattern.stdout assets/badges/self-hosted.svg
Commit: emit: a narrowed field in an or-pattern alternative is Some(..) (Fixes #1127)
Body: The checker kept #886/#902’s set parts only for a whole arm (set_positions by body), never for an Or arm. Now check_core_flow_fields_set / check_core_flow_variant_set compute them for any pattern, and check_core_flow_set_alternatives stores one list per alternative in the new CheckFacts::set_alternatives. The emitter’s set writer is pulled out as emit_core_set_pattern_written, and emit_core_arm_pattern_written writes each alternative with its own set. Names in an or-pattern stay untyped in the checker (as before), so only the lowering changes. Tuple or-patterns (#879) are left out because their narrowing changes the arm’s type.
Fixes: #1127
Tests: new a_narrowed_field_in_an_or_pattern (struct and variant shapes) passes –both-settings, fails on the unfixed binary (E0308); the 12 tests/compiler programs on #879/#886/#902 narrowing pass –both-settings; lower-std fixpoint clean; clippy –all-targets clean; pre-push-check green after badges.py
Gate: green
Deviation: none
Found: separate older defect (the unfixed binary has it too): an or-pattern binding of a positional variant’s String field that is filled only from literals lowers the field as &'static str, so s.clone() pushed into a Vec[String] is E0308. Probe: enum Pair { B(String, i64), D(String, i64), C }, match pair { Pair::B(s, _) | Pair::D(s, _) => s.clone(), else => continue } pushed to Vec[String], main builds [Pair::B("y", 3), Pair::D("z", 4), Pair::C]. A single Pair::B(s, _) arm works. Suspected cause: the field’s tier pass does not see the untyped or-pattern binding flow into owned text.
Needs: an issue for the Found defect; uncommitted lowered/emit_function_body.rs and lowered/emit_core_leaves.rs come from another agent’s .nika and were not staged
Changelog: Fixed: a T? field or variant value narrowed by an earlier null arm now lowers as Some(..) inside its own alternative of an or-pattern, not only in a single pattern (#1127).
Owner: none
Disk freed: none
Rs2nika: none
Attribution:
Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com
Claude-Session: https://claude.ai/code/session_01GFeMqxRbtUMiGVyDMxsvEq
Pushed: local 1b7fa366c94d611d4ab533a5b0f0e9634ec4aef1
