From d170d5fbaef463bdf11b32ed7db8ed067e42f25c Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Sat, 25 Apr 2026 00:14:15 +0000
Subject: [PATCH] lua: skip top-level guard when chunk has no top-level return;
 loadstring sees user globals

---
 lib/lua/scoreboard.json | 44 +++++++++++++++++++----------------------
 lib/lua/scoreboard.md   | 35 ++++++++++++++++----------------
 lib/lua/transpile.sx    | 33 ++++++++++++++++++++++++++++---
 plans/lua-on-sx.md      |  1 +
 4 files changed, 68 insertions(+), 45 deletions(-)

diff --git a/lib/lua/scoreboard.json b/lib/lua/scoreboard.json
index 6e6f18b6..ece8ffe3 100644
--- a/lib/lua/scoreboard.json
+++ b/lib/lua/scoreboard.json
@@ -1,8 +1,8 @@
 {
   "totals": {
     "pass": 1,
-    "fail": 12,
-    "timeout": 3,
+    "fail": 11,
+    "timeout": 4,
     "skip": 8,
     "total": 24,
     "runnable": 16,
@@ -15,16 +15,12 @@
     ],
     [
       "timeout",
-      3
+      4
     ],
     [
       "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
       2
     ],
-    [
-      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: module 'C' not found\\\\\\\"\\",
-      1
-    ],
     [
       "undefined symbol: fat\\",
       1
@@ -49,9 +45,9 @@
     },
     {
       "name": "attrib.lua",
-      "status": "fail",
-      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: module 'C' not found\\\\\\\"\\",
-      "ms": 6525
+      "status": "timeout",
+      "reason": "per-test timeout",
+      "ms": 8008
     },
     {
       "name": "big.lua",
@@ -63,7 +59,7 @@
       "name": "calls.lua",
       "status": "fail",
       "reason": "undefined symbol: fat\\",
-      "ms": 5092
+      "ms": 6184
     },
     {
       "name": "checktable.lua",
@@ -75,7 +71,7 @@
       "name": "closure.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8006
+      "ms": 8001
     },
     {
       "name": "code.lua",
@@ -87,7 +83,7 @@
       "name": "constructs.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to compare incompat",
-      "ms": 6780
+      "ms": 7870
     },
     {
       "name": "db.lua",
@@ -99,13 +95,13 @@
       "name": "errors.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 3208
+      "ms": 3808
     },
     {
       "name": "events.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 7307
+      "ms": 7990
     },
     {
       "name": "files.lua",
@@ -123,13 +119,13 @@
       "name": "literals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 1816
+      "ms": 2085
     },
     {
       "name": "locals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 1627
+      "ms": 1811
     },
     {
       "name": "main.lua",
@@ -141,43 +137,43 @@
       "name": "math.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 4156
+      "ms": 4436
     },
     {
       "name": "nextvar.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 7064
+      "ms": 7759
     },
     {
       "name": "pm.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 5813
+      "ms": 6473
     },
     {
       "name": "sort.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8008
+      "ms": 8007
     },
     {
       "name": "strings.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 3987
+      "ms": 4366
     },
     {
       "name": "vararg.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 2243
+      "ms": 2422
     },
     {
       "name": "verybig.lua",
       "status": "pass",
       "reason": "",
-      "ms": 1085
+      "ms": 1077
     }
   ]
 }
\ No newline at end of file
diff --git a/lib/lua/scoreboard.md b/lib/lua/scoreboard.md
index 30be0498..060e4435 100644
--- a/lib/lua/scoreboard.md
+++ b/lib/lua/scoreboard.md
@@ -1,14 +1,13 @@
 # Lua-on-SX conformance scoreboard
 
 **Pass rate:** 1/16 runnable (6.2%)
-fail=12 timeout=3 skip=8 total=24
+fail=11 timeout=4 skip=8 total=24
 
 ## Top failure modes
 
 - **7x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
-- **3x** timeout
+- **4x** timeout
 - **2x** other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio
-- **1x** other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\
 - **1x** undefined symbol: fat\
 - **1x** other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat
 
@@ -18,25 +17,25 @@ fail=12 timeout=3 skip=8 total=24
 |---|---|---|---:|
 | all.lua | skip | driver uses dofile to chain other tests | 0 |
 | api.lua | skip | requires testC (C debug library) | 0 |
-| attrib.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\ | 6525 |
+| attrib.lua | timeout | per-test timeout | 8008 |
 | big.lua | timeout | per-test timeout | 8007 |
-| calls.lua | fail | undefined symbol: fat\ | 5092 |
+| calls.lua | fail | undefined symbol: fat\ | 6184 |
 | checktable.lua | skip | internal debug helpers | 0 |
-| closure.lua | timeout | per-test timeout | 8006 |
+| closure.lua | timeout | per-test timeout | 8001 |
 | code.lua | skip | bytecode inspection via debug library | 0 |
-| constructs.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat | 6780 |
+| constructs.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat | 7870 |
 | db.lua | skip | debug library | 0 |
-| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3208 |
-| events.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7307 |
+| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3808 |
+| events.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7990 |
 | files.lua | skip | io library | 0 |
 | gc.lua | skip | collectgarbage / finalisers | 0 |
-| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 1816 |
-| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 1627 |
+| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2085 |
+| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 1811 |
 | main.lua | skip | standalone interpreter driver | 0 |
-| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 4156 |
-| nextvar.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7064 |
-| pm.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 5813 |
-| sort.lua | timeout | per-test timeout | 8008 |
-| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3987 |
-| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2243 |
-| verybig.lua | pass | - | 1085 |
+| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 4436 |
+| nextvar.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7759 |
+| pm.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6473 |
+| sort.lua | timeout | per-test timeout | 8007 |
+| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4366 |
+| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2422 |
+| verybig.lua | pass | - | 1077 |
diff --git a/lib/lua/transpile.sx b/lib/lua/transpile.sx
index 94b12e01..400d514d 100644
--- a/lib/lua/transpile.sx
+++ b/lib/lua/transpile.sx
@@ -568,12 +568,39 @@
                   (else sx)))))))
       (else sx))))
 
+(define
+  lua-has-top-return?
+  (fn (node)
+    (cond
+      ((not (= (type-of node) "list")) false)
+      ((= (len node) 0) false)
+      ((= (first node) (quote lua-return)) true)
+      ((or (= (first node) (quote lua-function))
+           (= (first node) (quote lua-local-function))
+           (= (first node) (quote lua-function-decl)))
+        false)
+      (else
+        (lua-has-top-return-children? (rest node) 0)))))
+
+(define
+  lua-has-top-return-children?
+  (fn (children i)
+    (cond
+      ((>= i (len children)) false)
+      ((lua-has-top-return? (nth children i)) true)
+      (else (lua-has-top-return-children? children (+ i 1))))))
+
 (define
   lua-eval-ast
   (fn (src)
-    (let ((sx (lua-transpile src)))
-      (let ((sx2 (lua-unwrap-final-return sx)))
-        (eval-expr (lua-tx-function-guard sx2))))))
+    (let ((parsed (lua-parse src)))
+      (let ((sx (lua-tx parsed)))
+        (let ((sx2 (lua-unwrap-final-return sx)))
+          (cond
+            ((lua-has-top-return? parsed)
+              (eval-expr (lua-tx-function-guard sx2)))
+            (else
+              (eval-expr sx2))))))))
 
 (define
   lua-tx-multi-args
diff --git a/plans/lua-on-sx.md b/plans/lua-on-sx.md
index 45fb945a..4d933d56 100644
--- a/plans/lua-on-sx.md
+++ b/plans/lua-on-sx.md
@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-25: lua: scoreboard iteration — `lua-eval-ast` now SKIPS the top-level guard when the parsed chunk has no top-level `return` (recursive AST walk via `lua-has-top-return?` that descends through control-flow but stops at function-body boundaries). Without the guard, top-level user defines leak to the SX top env, and `loadstring`-captured closures can find them. Verified: `function fat(x)...loadstring("return fat(...)")...end; x=fat(5)` works (was undefined). Most PUC-Rio tests still have top-level returns elsewhere, so they still need the guard. Scoreboard unchanged at 1/16 but unblocks future work.
 - 2026-04-25: lua: scoreboard iteration — math fns now error on bad/missing args (was silently returning 0). New `lua-math-num "name" x` validator wraps `abs`/`ceil`/`floor`/`sqrt`/`exp`/`sin`/`cos`/`tan`/`asin`/`acos`/`atan`/`atan2`/`pow`. errors.lua moves past assert #4 (`pcall(math.sin)` now returns false+err as expected).
 - 2026-04-24: lua: scoreboard iteration — **pattern character sets** `[...]` and `[^...]`. New `lua-pat-set-end`/`lua-pat-set-match` helpers handle ranges (`[a-z]`), classes inside sets (`[%d%a]`), negation (`[^abc]`), and `[]...]`/`[^]...]` (literal `]` as first char). Asserts 6→4, but timeouts 3→7 — many tests now reach loop-heavy code. 387/387 green (+3 charset tests).
 - 2026-04-24: lua: scoreboard iteration — `tonumber(s, base)` for bases 2-36. Validates digit ranges per base, supports leading `+`/`-`, trims whitespace. `math.lua` past assert #21. Asserts 8→6, timeouts 3→4. 384/384 green.