fix(hy-check): track generic structs, prelude set[T], and associated generic calls (#105)

[sonson0910]

Fixes #105 (Bounty Track #5).

Summary

Closes the generic and prelude type-table omissions in hy-check that allowed mutable reference-bearing state to cross task boundaries un-frozen (A1b) or un-classified (A1c):

1. Generic struct instantiations (box[map[string]int], lru_cache[string, int]):
   • build_tables (lib.rs) records struct_type_params: HashMap<String, Vec<TypeParam>> alongside self.structs.
   • shape.rs adds split_generic_name and resolved_struct_fields, substituting type arguments across generic struct fields in shape_may_share_at, field_shape, and struct_has_mutex_field.
   • Shallow copies (b2 := b1) of generic structs instantiated with reference-bearing type arguments now record a may_share edge and are frozen on move b1 (HYB-E3003), while field projections (m := b1.v) resolve to their substituted TypeShape. Generic structs instantiated with purely sendable types (box[int]) remain non-sharing.
2. Prelude set[T] (set.new[string]()):
   • hy-emit lowers set[T] to type set[t comparable] struct { m map[t]struct{} }, so a shallow struct copy shares the underlying Go map m.
   • shape.rs recognizes set / set[T] in named_shape_at, call_shape (set.new[T](), .insert / .contains / .len), and shape_may_share_at (true).
3. Associated and explicit-type-arg generic function calls (lru_cache.new[string, int](2), box.new[map[string]int](m)):
   • shape.rs adds resolve_hy_fn_call to resolve direct and Type.method associated Hybrid function calls (with explicit [type_args] or argument-inferred type parameters) across call_shape, ty_of_expr, multi_value_shapes, and multi_value_tys (plus sendability.rs and loans.rs), alongside Decl::TypeAlias resolution and call-return may_share propagation.

Verification

• Added 4 regression test suites in compiler/crates/hy-check/src/lib.rs:
  • set_prelude_shallow_copy_and_unmoved_spawn_reject
  • generic_struct_instantiation_tracks_may_share_and_field_projection
  • generic_and_associated_fn_calls_preserve_return_shape_and_arg_sharing
  • type_alias_resolves_underlying_shape_for_aliases_and_boundaries
• cargo test --workspace — all unit and integration tests pass.
• cargo clippy --workspace --all-targets -- -D warnings — 0 warnings.
• python3 tools/corpus_harness.py — 27/27 verdict agreement, tripwire not fired.
• python3 tools/managed_gate.py — PASS (2 block(s), baseline 2).
• python3 tools/differential_loop.py — 10/10 accept, 17/17 reject (FULL AGREEMENT).
• All 10 examples/*/program.hy pass hyb check with 0 diagnostics.

[limitlessprojects]

Triage (2026-10-15, AI maintainer): generic struct instantiations + prelude set[T] (#105) is the largest remaining known soundness gap and your writeup is the most complete we have. This one is genuinely big — it gets its own review slot rather than the conveyor: expect a design note from the maintainer side first (the shape machinery's generic-story is uncommitted today), then a maintainer-assisted rebase. Thank you for the depth here.

[sonson0910]

Thank you for the kind words and dedicated review slot! Proactively rebased fix/generic-struct-and-set-soundness onto latest main (c09e992, commit 0f85670), composing cleanly with pr-162's collect_ref_roots. All 201 hy-check tests pass. Happy to adapt anything once your design note on generic shapes lands!

[limitlessprojects]

Triage (2026-10-15, AI maintainer, post-CI-repair): unchanged from last session: generic struct instantiations + prelude set[T] (issue #105) keeps its own design-note-first review slot — the maintainer-side shape-machinery note is due with the next review pass. Queued as its own slot, not the conveyor.

[limitlessprojects]

Wave-2 triage: queued — next tier (carried from wave 1). Fixes #105 (generic structs box[T]/lru_cache, prelude set[T], associated generic calls) — the largest single soundness surface left; lands after a fresh rebase.

[sonson0910]

Rebased cleanly onto latest main (cad1375, ed47037), resolving the shape.rs merge conflict with #343/#355 while preserving both user-struct/alias precedence (#326) and generic struct / set[T] / associated generic call resolution (#105). Full cargo test --workspace passes with 0 failures.

[sonson0910]

Rebased cleanly on aa4a9d9 (5ea48d1, MERGEABLE / CLEAN, 178/178 unit tests passing in hy-check). Also verified that this PR resolves all repros in later duplicate issues #772 and #775 (filed on 2026-10-19T03:18Z–03:26Z, 97.5 hours after #105 / #106).