In article <87vfn8jvm3.fsf / serein.a02.aist.go.jp>,
  Tanaka Akira <akr / m17n.org> writes:

> これは適切な変更だと思いますが、変更するときには事前に警告するといきな
> り驚く人が少なくてすむと思います。

閉じるほうも警告するほうがいいかもしれません。

Index: regex.c
===================================================================
RCS file: /src/ruby/regex.c,v
retrieving revision 1.96
diff -p -u -r1.96 regex.c
--- regex.c	24 Dec 2003 08:47:36 -0000	1.96
+++ regex.c	19 Jan 2004 08:11:58 -0000
@@ -2181,6 +2181,7 @@ re_compile_pattern(pattern, size, bufp)
 
     unfetch_interval:
       /* If an invalid interval, match the characters as literals.  */
+      re_warning("regexp has invalid interval");
       p = beg_interval;
       beg_interval = 0;
 
@@ -2363,6 +2364,8 @@ re_compile_pattern(pattern, size, bufp)
     default:
       if (c == ']')
         re_warning("regexp has `]' without escape");
+      else if (c == '}')
+        re_warning("regexp has `}' without escape");
     normal_char:		/* Expects the character in `c'.  */
       had_mbchar = 0;
       if (ismbchar(c)) {
-- 
[田中 哲][たなか あきら][Tanaka Akira]