--- orig/gnugo-3.8/utils/gg_utils.c	2009-02-18 06:41:31
+++ gnugo-3.8/utils/gg_utils.c	2026-07-12 19:15:49
@@ -366,7 +366,10 @@
 {
   int gap = nel;
   int swap_made;
-  char *end = (char *) base + width * (nel - 1);
+  char *end;
+  if (nel < 2)
+    return; /* avoid UB pointer arithmetic when nel == 0 (wasm32) */
+  end = (char *) base + width * (nel - 1);
   do {
     char *a, *b;
     swap_made = 0;

# 追記: config.h は emscripten(wasm32)向けに以下を変更して生成:
#   SIZEOF_LONG=4, HAVE_CURSES_H=0, HAVE_TERM_H=0, TERMINFO無効