From 956014522830668c38b77e10740e9906d8ce6aa6 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Fri, 24 Apr 2026 21:29:43 +0000
Subject: [PATCH] lua: byte-to-char only single chars (fix \0-escape regression
 breaking string lengths)

---
 lib/lua/scoreboard.json | 32 ++++++++++++++++----------------
 lib/lua/scoreboard.md   | 32 ++++++++++++++++----------------
 lib/lua/tokenizer.sx    |  5 -----
 plans/lua-on-sx.md      |  1 +
 4 files changed, 33 insertions(+), 37 deletions(-)

diff --git a/lib/lua/scoreboard.json b/lib/lua/scoreboard.json
index 70055a22..58f05353 100644
--- a/lib/lua/scoreboard.json
+++ b/lib/lua/scoreboard.json
@@ -43,19 +43,19 @@
       "name": "attrib.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 5583
+      "ms": 5719
     },
     {
       "name": "big.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8007
+      "ms": 8006
     },
     {
       "name": "calls.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 4566
+      "ms": 4548
     },
     {
       "name": "checktable.lua",
@@ -67,7 +67,7 @@
       "name": "closure.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8007
+      "ms": 8003
     },
     {
       "name": "code.lua",
@@ -79,7 +79,7 @@
       "name": "constructs.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 4358
+      "ms": 4153
     },
     {
       "name": "db.lua",
@@ -91,13 +91,13 @@
       "name": "errors.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Not callable: nil (kont=10 frames)\\",
-      "ms": 3064
+      "ms": 2938
     },
     {
       "name": "events.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 6749
+      "ms": 6598
     },
     {
       "name": "files.lua",
@@ -115,13 +115,13 @@
       "name": "literals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 1802
+      "ms": 1859
     },
     {
       "name": "locals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 1557
+      "ms": 1687
     },
     {
       "name": "main.lua",
@@ -133,43 +133,43 @@
       "name": "math.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 3762
+      "ms": 3774
     },
     {
       "name": "nextvar.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 6669
+      "ms": 6637
     },
     {
       "name": "pm.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 5572
+      "ms": 5886
     },
     {
       "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": 3730
+      "ms": 4040
     },
     {
       "name": "vararg.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 2031
+      "ms": 2064
     },
     {
       "name": "verybig.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 534
+      "ms": 545
     }
   ]
 }
\ No newline at end of file
diff --git a/lib/lua/scoreboard.md b/lib/lua/scoreboard.md
index 4a393e70..1c80f585 100644
--- a/lib/lua/scoreboard.md
+++ b/lib/lua/scoreboard.md
@@ -16,25 +16,25 @@ fail=13 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: \\\"assertion failed!\\\"\ | 5583 |
-| big.lua | timeout | per-test timeout | 8007 |
-| calls.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4566 |
+| attrib.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 5719 |
+| big.lua | timeout | per-test timeout | 8006 |
+| calls.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4548 |
 | checktable.lua | skip | internal debug helpers | 0 |
-| closure.lua | timeout | per-test timeout | 8007 |
+| closure.lua | timeout | per-test timeout | 8003 |
 | code.lua | skip | bytecode inspection via debug library | 0 |
-| constructs.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4358 |
+| constructs.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4153 |
 | db.lua | skip | debug library | 0 |
-| errors.lua | fail | other: Unhandled exception: \"Not callable: nil (kont=10 frames)\ | 3064 |
-| events.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6749 |
+| errors.lua | fail | other: Unhandled exception: \"Not callable: nil (kont=10 frames)\ | 2938 |
+| events.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6598 |
 | files.lua | skip | io library | 0 |
 | gc.lua | skip | collectgarbage / finalisers | 0 |
-| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 1802 |
-| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 1557 |
+| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 1859 |
+| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 1687 |
 | main.lua | skip | standalone interpreter driver | 0 |
-| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3762 |
-| nextvar.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6669 |
-| pm.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 5572 |
-| sort.lua | timeout | per-test timeout | 8008 |
-| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3730 |
-| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2031 |
-| verybig.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 534 |
+| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3774 |
+| nextvar.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6637 |
+| pm.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 5886 |
+| sort.lua | timeout | per-test timeout | 8007 |
+| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4040 |
+| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2064 |
+| verybig.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 545 |
diff --git a/lib/lua/tokenizer.sx b/lib/lua/tokenizer.sx
index f0c4cc6e..b5a73f4d 100644
--- a/lib/lua/tokenizer.sx
+++ b/lib/lua/tokenizer.sx
@@ -3,13 +3,8 @@
 (define lua-byte-to-char
   (fn (n)
     (cond
-      ((= n 0) "\0")
-      ((= n 7) "\a")
-      ((= n 8) "\b")
       ((= n 9) "\t")
       ((= n 10) "\n")
-      ((= n 11) "\v")
-      ((= n 12) "\f")
       ((= n 13) "\r")
       ((and (>= n 32) (<= n 126)) (char-at __ascii-tok (- n 32)))
       (else "?"))))
diff --git a/plans/lua-on-sx.md b/plans/lua-on-sx.md
index 65bc7a8d..082f9ab1 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._
 
+- 2026-04-24: lua: scoreboard iteration — `lua-byte-to-char` regression fix. My previous change returned 2-char strings (`"\a"` etc.) for bytes that SX string literals can't express (0, 7, 8, 11, 12, 14–31, 127+), breaking `'a\0a'` length from 3 → 4. Now only 9/10/13 and printable 32-126 produce real bytes; others use a single `"?"` placeholder so `string.len` stays correct. literals.lua back to failing at assert #4 (was regressed to #2).
 - 2026-04-24: lua: scoreboard iteration — **decimal string escapes** `\ddd` (1-3 digits). Tokenizer `read-string` previously fell through to literal for digits, so `"\65"` came out as `"65"` not `"A"`. Added `read-decimal-escape!` consuming up to 3 digits while keeping value ≤255, plus `\a`/`\b`/`\f`/`\v` control escapes and `lua-byte-to-char` ASCII lookup. 362 tests (+2 escape tests).
 - 2026-04-24: lua: scoreboard iteration — **`loadstring` error propagation**. When `loadstring(s)()` was implemented as `eval-expr ( (let () compiled))`, SX's `eval-expr` wrapped any propagated `raise` as "Unhandled exception: X" — so `error('hi')` inside a loadstring'd chunk came out as that wrapped string instead of the clean `"hi"` Lua expects. Fix: transpile source once into a lambda AST, `eval-expr` it ONCE to get a callable fn value, return that — subsequent calls propagate raises cleanly. Guarded parse-failure path returns `(nil, err)` per Lua convention. vararg.lua now runs past assert #18; errors.lua past parse stage.
 - 2026-04-24: lua: scoreboard iteration — `table.sort` O(n²) insertion-sort → **quicksort** (Lomuto partition). 1000-element sorts finish in ms; but `sort.lua` uses 30k elements and still times out even at 90s (metamethod-heavy interpreter overhead). Correctness verified on 1000/5000 element random arrays.