erlang: verify hot-reload call dispatch semantics (+6 eval tests)

lib/erlang/scoreboard.json

@@ -1,11 +1,11 @@
 {
   "language": "erlang",
-  "total_pass": 571,
+  "total_pass": 577,
-  "total": 571,
+  "total": 577,
   "suites": [
     {"name":"tokenize","pass":62,"total":62,"status":"ok"},
     {"name":"parse","pass":52,"total":52,"status":"ok"},
-    {"name":"eval","pass":374,"total":374,"status":"ok"},
+    {"name":"eval","pass":380,"total":380,"status":"ok"},
     {"name":"runtime","pass":52,"total":52,"status":"ok"},
     {"name":"ring","pass":4,"total":4,"status":"ok"},
     {"name":"ping-pong","pass":4,"total":4,"status":"ok"},

lib/erlang/scoreboard.md

@@ -1,12 +1,12 @@
 # Erlang-on-SX Scoreboard
 
-**Total: 571 / 571 tests passing**
+**Total: 577 / 577 tests passing**
 
 |  | Suite | Pass | Total |
 |---|---|---|---|
 | ✅ | tokenize | 62 | 62 |
 | ✅ | parse | 52 | 52 |
-| ✅ | eval | 374 | 374 |
+| ✅ | eval | 380 | 380 |
 | ✅ | runtime | 52 | 52 |
 | ✅ | ring | 4 | 4 |
 | ✅ | ping-pong | 4 | 4 |

lib/erlang/tests/eval.sx

@@ -1252,6 +1252,63 @@
 (er-eval-test "code:is_loaded badarg"
   (nm (ev "try code:is_loaded(123) catch error:badarg -> ok end")) "ok")
 
+
+;; ── Phase 7: hot-reload call dispatch semantics ──────────────────
+;; Cross-module M:F() calls always hit the CURRENT version;
+;; local F() calls inside a module body resolve through the env
+;; the function closed over (i.e. the version it was loaded with).
+
+(er-modules-reset!)
+
+;; M:F always hits current
+(er-eval-test "cross-mod after reload v2"
+  (ev "code:load_binary(hr1, \"hr1\", \"-module(hr1). f() -> 1.\"),
+       code:load_binary(hr1, \"hr1\", \"-module(hr1). f() -> 2.\"),
+       hr1:f()")
+  2)
+
+;; Local call inside reloaded module body resolves via fresh mod-env
+;; (a() does a local b(); b() got upgraded too)
+(er-eval-test "local call inside reloaded module body"
+  (ev "code:load_binary(hr2, \"hr2\", \"-module(hr2). a() -> b(). b() -> 1.\"),
+       code:load_binary(hr2, \"hr2\", \"-module(hr2). a() -> b(). b() -> 99.\"),
+       hr2:a()")
+  99)
+
+;; Fun captured BEFORE reload, with local-call body, keeps v1 semantics
+(er-eval-test "captured fun keeps closed-over env (local call)"
+  (ev "code:load_binary(hr3, \"hr3\", \"-module(hr3). get_fn() -> fun () -> b() end. b() -> 1.\"),
+       Fn = hr3:get_fn(),
+       code:load_binary(hr3, \"hr3\", \"-module(hr3). get_fn() -> fun () -> b() end. b() -> 99.\"),
+       Fn()")
+  1)
+
+;; Fun captured BEFORE reload, with CROSS-mod body, sees v2's current
+(er-eval-test "captured fun follows cross-mod to current"
+  (ev "code:load_binary(hr4, \"hr4\", \"-module(hr4). get_xref() -> fun () -> hr4:b() end. b() -> 1.\"),
+       Fn = hr4:get_xref(),
+       code:load_binary(hr4, \"hr4\", \"-module(hr4). get_xref() -> fun () -> hr4:b() end. b() -> 99.\"),
+       Fn()")
+  99)
+
+;; Two captured funs from two different vintages
+(er-eval-test "two funs from two vintages stay independent"
+  (ev "code:load_binary(hr5, \"hr5\", \"-module(hr5). gf() -> fun () -> v() end. v() -> 10.\"),
+       F1 = hr5:gf(),
+       code:load_binary(hr5, \"hr5\", \"-module(hr5). gf() -> fun () -> v() end. v() -> 20.\"),
+       F2 = hr5:gf(),
+       F1() + F2()")
+  30)
+
+;; Version slot bumps correctly when a captured fun stays alive
+(er-eval-test "version bumps despite captured funs"
+  (ev "code:load_binary(hr6, \"hr6\", \"-module(hr6). gf() -> fun () -> v() end. v() -> 1.\"),
+       _Pinned = hr6:gf(),
+       code:load_binary(hr6, \"hr6\", \"-module(hr6). gf() -> fun () -> v() end. v() -> 2.\"),
+       code:load_binary(hr6, \"hr6\", \"-module(hr6). gf() -> fun () -> v() end. v() -> 3.\"),
+       hr6:v()")
+  3)
+
 (define
   er-eval-test-summary
   (str "eval " er-eval-test-pass "/" er-eval-test-count))

plans/erlang-on-sx.md

@@ -105,7 +105,7 @@ Driven by **fed-sx** (see `plans/fed-sx-design.md` §17.5): federated modules mu
 - [x] `code:load_binary/3` (the canonical reload BIF) — re-parses module source, swaps `:current` → `:old`, installs new env as `:current`; returns `{module, Name}` or `{error, Reason}` (badarg / badfile / module_name_mismatch). **+8 eval tests** (551/551 total). `code:load_file/1` is a thin filesystem wrapper around this and lands once `file:read_file/1` is in (Phase 8).
 - [x] `code:purge/1` + `code:soft_purge/1` — purge clears `:old` slot and kills any process whose `:initial-fun` env identity matches the old env (returns `true` if there was old code, `false` if there wasn't). soft_purge: refuses (returns `false`, leaves `:old` intact) if any process is still pinned to the old env; otherwise clears and returns `true`. **+10 eval tests** (561/561 total). Caveat: a true "lingering on old code" test needs `spawn/3` (still stubbed) or `fun M:F/A` syntax (not parsed) — anonymous `fun () -> M:F() end` closures capture the caller's env, not the module's, and cross-module calls always resolve to `:current`. Current tests therefore exercise the return-value matrix but not the kill path.
 - [x] `code:which/1`, `code:is_loaded/1`, `code:all_loaded/0` — introspection. **+10 eval tests** (571/571 total). Return-value contract: `which` → `loaded` / `non_existing` (since we have no filesystem path); `is_loaded` → `{file, loaded}` / `false`; `all_loaded` → list of `{Module, loaded}` tuples. Non-atom Mod raises `error:badarg`.
-- [ ] Cross-module call `M:F(...)` dispatches to `:current`; local calls inside a module body keep using the env they closed over so a running process finishes its current function with the version it started with
+- [x] Cross-module call `M:F(...)` dispatches to `:current`; local calls inside a module body keep using the env they closed over so a running process finishes its current function with the version it started with — **+6 eval tests** verifying the property end-to-end (577/577 total). No implementation change: `er-apply-user-module` already routes through `er-module-current-env`, and `er-mk-fun` captures its env by reference so closures created under v1 retain v1's `mod-env` even after the slot bumps to v2.
 - [ ] Tests: load v1 → spawn → load v2 → cross-module call hits v2 → local call inside v1 process keeps v1 semantics until function returns → purge kills v1 procs → soft_purge refuses while v1 procs alive
 
 ### Phase 8 — FFI BIF mechanism + standard libs
@@ -126,6 +126,8 @@ Replace today's hardcoded BIF dispatch (`er-apply-bif`/`er-apply-remote-bif` in
 
 _Newest first._
 
+- **2026-05-14 hot-reload call-dispatch semantics verified** — Tests-only iteration: no implementation change, just six new eval tests that nail down the Erlang semantics already implicit in the current code. (1) `M:F()` after reload returns v2's value (cross-module call hits `:current`). (2) Inside a freshly-loaded body, a bare local call resolves through the new mod-env so a chain `a() -> b()` reflects v2's `b/0`. (3) Calling a fun captured BEFORE reload, whose body uses a local call, returns the v1 value (closure pinned to old mod-env via `er-mk-fun`'s `:env` reference). (4) Calling a fun captured BEFORE reload, whose body uses a cross-module call `M:b()`, returns v2's value (cross-module always wins over closed-over env). (5) Two captured funs from two distinct vintages stay independent — F1() + F2() = 10 + 20 = 30. (6) The slot version counter still bumps even while old captured funs are alive, demonstrating the closure-pinning doesn't block reloads. The "running process finishes its current function with the version it started with" property falls out of fun-as-closure semantics for free — there's no special bookkeeping. Total **577/577** (+6 eval).
+
 - **2026-05-14 code introspection BIFs green** — `code:which/1`, `code:is_loaded/1`, `code:all_loaded/0` added to `er-apply-code-bif` dispatch with three small implementations in `transpile.sx`. `which` and `is_loaded` are dict-lookups on the module registry returning the loaded-marker (atom `loaded`) or the missing-marker (atom `non_existing` for which, atom `false` for is_loaded). Since we don't have a filesystem path representation, the standard `{file, Path}` shape for `is_loaded` becomes `{file, loaded}` — same tuple arity so destructuring code stays portable. `all_loaded` iterates `(keys (er-modules-get))` in reverse (so the result list preserves insertion order after the cons-prepend loop), wrapping each name in a `{Module, loaded}` tuple. **10 new eval tests**: non_existing for absent / loaded after load for which; missing / file-tag / loaded-value for is_loaded; empty / count-after-2-loads / first-entry-tag for all_loaded; badarg for both single-arg BIFs. Two of the all_loaded tests needed an explicit `(er-modules-reset!)` before the measurement because prior tests in the suite leave modules registered (the registry is process-global across the whole epoch session). Total **571/571** (+10 eval).
 
 - **2026-05-14 code:purge/1 + code:soft_purge/1 green** — Two new BIFs in `transpile.sx`: `er-bif-code-purge` and `er-bif-code-soft-purge`, both dispatched through the existing `er-apply-code-bif` cond chain. Shared helper `er-procs-on-env` walks `(er-sched-processes)` and collects pids whose `:initial-fun` is a fun whose `:env` is identical (dict-identity, not structural) to a given env, filtering out already-dead procs. `er-bif-code-purge` looks up the module slot, returns `false` if either the module isn't registered or `:old` is nil; otherwise calls `er-cascade-exit!` on every matching pid with reason `killed`, replaces the slot with a fresh `er-mk-module-slot` that has `:old nil` (current + version preserved), returns `true`. `er-bif-code-soft-purge` returns `true` (treating "no module" / "no old version" as already-purged), else checks for lingering procs and returns `false` (leaving the slot untouched) if any, else clears `:old` and returns `true`. Non-atom Mod raises `error:badarg` from both. **10 new eval tests**: unknown / no-old / after-reload / idempotent for purge; unknown / no-old / clean for soft_purge; badarg for both; one "purge after spawn" test verifying return value (does NOT exercise the kill path — see caveat in plan). Total **561/561** (+10 eval). Implementation cost: 1 dispatch entry, 3 small BIFs, no scheduler changes.