* bignum.c (get2comp): do nothing for empty Bignum. [ruby-dev:31225]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12796 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,7 @@
+Sun Jul 15 21:07:43 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* bignum.c (get2comp): do nothing for empty Bignum.  [ruby-dev:31225]
+
 Sun Jul 15 19:05:28 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* bignum.c (rb_cstr_to_inum): check leading non-digits.

bignum.c

@@ -97,7 +97,7 @@ bigtrunc(VALUE x)
     long len = RBIGNUM(x)->len;
     BDIGIT *ds = BDIGITS(x);
 
-    while (len-- && !ds[len]);
+    while (--len && !ds[len]);
     RBIGNUM(x)->len = ++len;
     return x;
 }
@@ -1038,6 +1038,7 @@ rb_big_neg(VALUE x)
     if (!RBIGNUM(x)->sign) get2comp(z);
     ds = BDIGITS(z);
     i = RBIGNUM(x)->len;
+    if (!i) return INT2FIX(~(SIGNED_VALUE)0);
     while (i--) {
 	ds[i] = ~ds[i];
     }