From 1b34d41b3376e2e4310dd8cf169a17cfb05533db Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Sat, 25 Apr 2026 00:31:03 +0000
Subject: [PATCH] lua: unpack treats explicit nil i/j as missing (defaults to 1
 and #t)

---
 lib/lua/runtime.sx      | 36 +++++++++++++++++---------------
 lib/lua/scoreboard.json | 46 ++++++++++++++++++++++-------------------
 lib/lua/scoreboard.md   | 33 +++++++++++++++--------------
 plans/lua-on-sx.md      |  1 +
 4 files changed, 62 insertions(+), 54 deletions(-)

diff --git a/lib/lua/runtime.sx b/lib/lua/runtime.sx
index 3c148e08..cf711f0f 100644
--- a/lib/lua/runtime.sx
+++ b/lib/lua/runtime.sx
@@ -1552,23 +1552,25 @@
 (define
   lua-unpack
   (fn (&rest args)
-    (let ((t (first args))
-          (i (if (> (len args) 1) (nth args 1) 1))
-          (j (if (> (len args) 2) (nth args 2) (lua-len (first args)))))
-      (cond
-        ((> i j) nil)
-        (else
-          (let ((out (list (quote lua-multi))))
-            (begin
-              (define
-                loop
-                (fn (k)
-                  (when (<= k j)
-                    (begin
-                      (set! out (append out (list (get t (str k)))))
-                      (loop (+ k 1))))))
-              (loop i)
-              out)))))))
+    (let ((t (first args)))
+      (let ((i-raw (if (> (len args) 1) (nth args 1) nil))
+            (j-raw (if (> (len args) 2) (nth args 2) nil)))
+        (let ((i (if (= i-raw nil) 1 i-raw))
+              (j (if (= j-raw nil) (lua-len t) j-raw)))
+          (cond
+            ((> i j) nil)
+            (else
+              (let ((out (list (quote lua-multi))))
+                (begin
+                  (define
+                    loop
+                    (fn (k)
+                      (when (<= k j)
+                        (begin
+                          (set! out (append out (list (get t (str k)))))
+                          (loop (+ k 1))))))
+                  (loop i)
+                  out)))))))))
 
 (define
   lua-table-maxn
diff --git a/lib/lua/scoreboard.json b/lib/lua/scoreboard.json
index ef127e69..1a4fbd86 100644
--- a/lib/lua/scoreboard.json
+++ b/lib/lua/scoreboard.json
@@ -1,8 +1,8 @@
 {
   "totals": {
     "pass": 1,
-    "fail": 7,
-    "timeout": 8,
+    "fail": 9,
+    "timeout": 6,
     "skip": 8,
     "total": 24,
     "runnable": 16,
@@ -11,16 +11,20 @@
   "top_failure_modes": [
     [
       "timeout",
-      8
+      6
     ],
     [
       "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      4
+      5
     ],
     [
       "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
@@ -41,21 +45,21 @@
     },
     {
       "name": "attrib.lua",
-      "status": "timeout",
-      "reason": "per-test timeout",
-      "ms": 8000
+      "status": "fail",
+      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: module 'C' not found\\\\\\\"\\",
+      "ms": 6985
     },
     {
       "name": "big.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8007
+      "ms": 8008
     },
     {
       "name": "calls.lua",
       "status": "fail",
       "reason": "undefined symbol: fat\\",
-      "ms": 6732
+      "ms": 5721
     },
     {
       "name": "checktable.lua",
@@ -67,7 +71,7 @@
       "name": "closure.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8005
+      "ms": 8008
     },
     {
       "name": "code.lua",
@@ -91,7 +95,7 @@
       "name": "errors.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 4579
+      "ms": 4667
     },
     {
       "name": "events.lua",
@@ -115,13 +119,13 @@
       "name": "literals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 2829
+      "ms": 2950
     },
     {
       "name": "locals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 2598
+      "ms": 2366
     },
     {
       "name": "main.lua",
@@ -133,19 +137,19 @@
       "name": "math.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 6606
+      "ms": 4991
     },
     {
       "name": "nextvar.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8008
+      "ms": 8007
     },
     {
       "name": "pm.lua",
-      "status": "timeout",
-      "reason": "per-test timeout",
-      "ms": 8009
+      "status": "fail",
+      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
+      "ms": 6697
     },
     {
       "name": "sort.lua",
@@ -157,19 +161,19 @@
       "name": "strings.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 6228
+      "ms": 4493
     },
     {
       "name": "vararg.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 3087
+      "ms": 2541
     },
     {
       "name": "verybig.lua",
       "status": "pass",
       "reason": "",
-      "ms": 1058
+      "ms": 1187
     }
   ]
 }
\ No newline at end of file
diff --git a/lib/lua/scoreboard.md b/lib/lua/scoreboard.md
index 50da0d66..a1db5ec8 100644
--- a/lib/lua/scoreboard.md
+++ b/lib/lua/scoreboard.md
@@ -1,13 +1,14 @@
 # Lua-on-SX conformance scoreboard
 
 **Pass rate:** 1/16 runnable (6.2%)
-fail=7 timeout=8 skip=8 total=24
+fail=9 timeout=6 skip=8 total=24
 
 ## Top failure modes
 
-- **8x** timeout
-- **4x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
+- **6x** timeout
+- **5x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
 - **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\
 
 ## Per-test results
@@ -16,25 +17,25 @@ fail=7 timeout=8 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 | timeout | per-test timeout | 8000 |
-| big.lua | timeout | per-test timeout | 8007 |
-| calls.lua | fail | undefined symbol: fat\ | 6732 |
+| attrib.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\ | 6985 |
+| big.lua | timeout | per-test timeout | 8008 |
+| calls.lua | fail | undefined symbol: fat\ | 5721 |
 | checktable.lua | skip | internal debug helpers | 0 |
-| closure.lua | timeout | per-test timeout | 8005 |
+| closure.lua | timeout | per-test timeout | 8008 |
 | code.lua | skip | bytecode inspection via debug library | 0 |
 | constructs.lua | timeout | per-test timeout | 8007 |
 | db.lua | skip | debug library | 0 |
-| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4579 |
+| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4667 |
 | events.lua | timeout | per-test timeout | 8007 |
 | files.lua | skip | io library | 0 |
 | gc.lua | skip | collectgarbage / finalisers | 0 |
-| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2829 |
-| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 2598 |
+| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2950 |
+| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 2366 |
 | main.lua | skip | standalone interpreter driver | 0 |
-| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 6606 |
-| nextvar.lua | timeout | per-test timeout | 8008 |
-| pm.lua | timeout | per-test timeout | 8009 |
+| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 4991 |
+| nextvar.lua | timeout | per-test timeout | 8007 |
+| pm.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6697 |
 | sort.lua | timeout | per-test timeout | 8007 |
-| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6228 |
-| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3087 |
-| verybig.lua | pass | - | 1058 |
+| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4493 |
+| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2541 |
+| verybig.lua | pass | - | 1187 |
diff --git a/plans/lua-on-sx.md b/plans/lua-on-sx.md
index 719fa5c8..929b6a93 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 — `unpack(t, i, j)` now treats explicit nil for `i` or `j` as missing (defaults to 1 and `#t`). vararg.lua-style `unpack(args, 1, args.n)` works when `args.n` is nil. Asserts 4→5, timeouts 8→6 (more tests reach assertions instead of timing out). 393/393 green.
 - 2026-04-25: lua: scoreboard iteration — extended `string.format`. New `%x`/`%X`/`%o` (hex/octal), `%c` (codepoint→char via `lua-char-one`), `%q` (basic quote), width N (`%5d`), zero-pad (`%05d`), left-align (`%-5d`), `%.Ns` precision. Helpers `lua-fmt-pad` and `lua-fmt-int-base`. 393/393 green (+6 format tests).
 - 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).