[Burapa-J]

Fixes #3893

Cause

1. has_non_sendable_leaf (compiler/crates/hy-check/src/sendability.rs:41-68) omitted set[T] when checking composite leaf types.
2. check_stmt_chan_direction (sendability.rs:845-875) did not bind user-defined enum variant payload bindings in Stmt::Match arms.
3. check_spawn_callee (sendability.rs:146-184) checked self.fn_result_count before checking lexical/const bindings and did not check whether package roots (fmt.println) were shadowed.
4. walk_chan_dir_expr did not check self.is_close_shadowed(st) on close(...) calls.

Fix

• Recurse into set[...] in has_non_sendable_leaf.
• Resolve user-defined enum variant payload types in check_stmt_chan_direction (resolve_enum_arm_dir_ty) and shadow non-channel binders.
• Check self.lookup_binding(st, name) and package root shadowing first in check_spawn_callee, and guard close(...) with !self.is_close_shadowed(st).
• Add regression tests in compiler/crates/hy-check/tests/callee_and_nil.rs.

Verification

• cargo test -p hy-check --lib --test callee_and_nil --test make_directional_channel_issue_1804 (208 passed, 0 failed)

Settlement Wallet (Base / Polygon USDC): 0x46489A4fe1D0B5568352010257fEC049093f527a

---

Maintainer / Shepherd Queue Note (Session 145)

1. Pagination Alert (#3843..#3854 are still OPEN & ALL-GREEN):
   • Because > 80 newer PRs (#3858..#4079) were opened, PRs below #3858 slipped onto Page 2 of /pulls?state=open, which caused Session 142's queue check to assume #3820..#3857 were no longer open.
   • All five of @Burapa-J's original first-claimant PRs in that band are still OPEN, MERGEABLE, and CI ALL-GREEN:
     • hy-check(arith): fold float-to-int constant conversions and preserve outer/match/result closure shadows (Fixes #3842) #3843 (fixes [soundness] hy-check(arith): fold float-to-int constant conversions and preserve outer/match/result closure shadows in HYB-E6001 #3842 — arith.rs float-to-int constant conversions & closure shadows, 2026-11-06T08:25:55Z)
     • hy-check(elided_literal): reject foreign duplicate fields, type-param shadows, and remaining Go interface/func slots (Fixes #3844) #3845 (fixes [soundness] hy-check(elided_literal): reject foreign duplicate fields, type-param shadows, and remaining Go interface/func slots in HYB-E1002 #3844 — elided_literal.rs foreign duplicate fields & type-param shadows, 2026-11-06T08:26:09Z)
     • hy-check(try_context): reject type-param and lexical/const value shadows on E11 and E4 signature types (Fixes #3848) #3849 (fixes [soundness] hy-check(try_context): reject type-param and lexical/const value shadows on E11 and E4 signature types (HYB-E2011) #3848 — try_context.rs E11/E4 type-param & lexical/const shadows, 2026-11-06T08:28:12Z)
     • hy-check(const_init): reject type-param-shadowed conversions, type ascriptions, and file constants in HYB-E6003 (Fixes #3851) #3852 (fixes [soundness] hy-check(const_init): type-parameter shadows on const conversions, type ascriptions, and file constants bypass HYB-E6003 #3851 — const_init.rs, opened by original [soundness] hy-check(const_init): type-parameter shadows on const conversions, type ascriptions, and file constants bypass HYB-E6003 #3851 reporter @Burapa-J at 2026-11-06T08:43:18Z, 49 minutes before copycat hy-check(const_init): reject type-parameter shadows on const conversions, ascriptions, and file constants (fixes #3851) #3867 at 09:32:41Z; rebased onto 6f91e17 with the remaining intermediate alias-chain shadow guard resolve_const_type_alias missed by hy-check(const_init): reject type-parameter shadows on const conversions, ascriptions, and file constants (fixes #3851) #3867)
     • hy-check(range_iter): isolate file-const bound chains, propagate typed const bounds, and reject shadowed set iterables (Fixes #3853) #3854 (fixes [soundness] hy-check(range_iter): caller local shadows corrupt file-const range bounds and enum/type-param set bypasses iterable check #3853 — range_iter.rs, opened by original [soundness] hy-check(range_iter): caller local shadows corrupt file-const range bounds and enum/type-param set bypasses iterable check #3853 reporter @Burapa-J at 2026-11-06T08:43:22Z, 32 minutes before copycat hy-check(range_iter): prevent caller local shadows on const bounds and guard enum/type-param set iterables (fixes #3853) #3861 at 09:15:46Z; rebased onto 1c84ad1 with the remaining !st.type_params.contains(name) & !self.consts.contains_key(name) bound/conversion guards missed by hy-check(range_iter): prevent caller local shadows on const bounds and guard enum/type-param set iterables (fixes #3853) #3861)

[limitlessprojects]

Landed — 6c1a0602

Merged to main with git merge --no-ff and a hand-written credit commit (CREDIT: @Burapa-J). Three genuine blind spots closed in one coherent patch — the set[T] recursion was the most overdue (any set[closure] or set[sync.mutex] sailed through).

Gate	Result
Trial merge vs current main	clean (2 files: sendability.rs + callee_and_nil.rs)
Extended suite standalone	callee_and_nil — 20/20 pass
cargo test --workspace	exit 0, 488 suites, 3128 passed, 0 failed
Corpus harness	135/135 verdict agreement, tripwire not fired
Differential loop FULL	45/45 accept-side, 90/90 reject-side — FULL AGREEMENT

Review notes

• The user-defined-set guard (!structs.contains_key("set")) on all three recursion sites matches the convention the rest of the checker follows (hy-check(range_iter): prevent caller local shadows on const bounds and guard enum/type-param set iterables (fixes #3853) #3861/hy-check(shape): track handle provenance across set[T] and unresolved generic structs and guard shadowed call shapes (Fixes #3859) #3860 lineage) — user shadows always win.
• Moving the Unproven-tp arm from top-level to fallback tail is the right classification order: a set[fn()] now reports the precise E3001 (closure) instead of the vaguer Unproven, and Unproven still fires before Ok.
• Spawn-callee shadow extension (type-param/struct/enum/alias → Unproven, not Proven) closes a proof gap where fn launch[work]() could smuggle a type name past O4.0 — fixture locks exactly that shape.
• resolve_enum_arm_dir_ty gives match-arm binders real types; the E3008/E3009 fixtures through pkt.rx(ch)/pkt.tx(ch) are the first chan-direction checks that see inside enum matches.
• Reject-face widening; no accept-side regressions (3128 green, corpus silent, differential full agreement, sendable-set control accepted).

Bounty

Per BOUNTY.md / discussion #295: this lands against issue #3893 — bounty claim recorded for @Burapa-J on that issue's rail.