+
+You may if you wish apply the following patch to bison.simple:
+diff -pu -r1.28.0.1 -r1.28.0.3
+--- bison.s1 1999/08/30 19:23:24 1.28.0.1
++++ bison.s1 1999/08/30 21:15:18 1.28.0.3
+@@ -523,8 +523,14 @@ yydefault:
+ /* Do a reduction. yyn is the number of a rule to reduce with. */
+ yyreduce:
+ yylen = yyr2[yyn];
+- if (yylen > 0)
+- yyval = yyvsp[1-yylen]; /* implement default value of the action */
++
++ /* If yylen is nonzero, implement the default value of the action.
++ Otherwise, the following line sets yyval to the semantic value of
++ the lookahead token. This behavior is undocumented and bison
++ users should not rely upon it. Assigning to yyval
++ unconditionally makes the parser a bit smaller, and it avoids a
++ GCC warning that yyval may be used uninitialized. */
++ yyval = yyvsp[1-yylen];
+
+ #if YYDEBUG != 0
+ if (yydebug)