* src/nullable.c (set_nullable): Useless rules must be skipped,

otherwise, since we range over their symbols, we might look at a
nonterminal which no longer ``exists'', i.e., it is not counted in
`nvars', hence we overflow our arrays.

diff --git a/ChangeLog b/ChangeLog
index ca964b73dd51e186989990fb48b8ae8b7f54a948..21c7c4734fcb0f27424b59a6e20aa30feefe76b5 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2001-12-15  Akim Demaille  <akim@epita.fr>
+
+       * src/nullable.c (set_nullable): Useless rules must be skipped,
+       otherwise, since we range over their symbols, we might look at a
+       nonterminal which no longer ``exists'', i.e., it is not counted in
+       `nvars', hence we overflow our arrays.
+
 2001-12-15  Akim Demaille  <akim@epita.fr>
 
        The header can also be produced directly, without any obstack!

diff --git a/src/nullable.c b/src/nullable.c
index bbd8e3197d4dd6b11c064c00c9e40f0d7a138916..000b8b1be0a85c6df5f84254c2568c93749e789a 100644 (file)
--- a/src/nullable.c
+++ b/src/nullable.c
@@ -69,35 +69,38 @@ set_nullable (void)
   p = relts;
 
   for (ruleno = 1; ruleno < nrules + 1; ++ruleno)
-    if (ritem[rule_table[ruleno].rhs] > 0)
+    if (rule_table[ruleno].useful)
       {
-       /* This rule has a non empty RHS. */
-       short *r;
-       int any_tokens = 0;
-       for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
-         if (ISTOKEN (*r))
-           any_tokens = 1;
-
-       /* This rule has only nonterminals: schedule it for the second
-          pass.  */
-       if (!any_tokens)
-         for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
-           {
-             rcount[ruleno]++;
-             p->next = rsets[*r];
-             p->value = ruleno;
-             rsets[*r] = p;
-             p++;
-           }
-      }
-    else
-      {
-       /* This rule has an empty RHS. */
-       assert (ritem[rule_table[ruleno].rhs] == -ruleno);
-       if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])
+       if (ritem[rule_table[ruleno].rhs] > 0)
+         {
+           /* This rule has a non empty RHS. */
+           short *r;
+           int any_tokens = 0;
+           for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
+             if (ISTOKEN (*r))
+               any_tokens = 1;
+
+           /* This rule has only nonterminals: schedule it for the second
+              pass.  */
+           if (!any_tokens)
+             for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
+               {
+                 rcount[ruleno]++;
+                 p->next = rsets[*r];
+                 p->value = ruleno;
+                 rsets[*r] = p;
+                 p++;
+               }
+         }
+       else
          {
-           nullable[rule_table[ruleno].lhs] = 1;
-           *s2++ = rule_table[ruleno].lhs;
+           /* This rule has an empty RHS. */
+           assert (ritem[rule_table[ruleno].rhs] == -ruleno);
+           if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])
+             {
+               nullable[rule_table[ruleno].lhs] = 1;
+               *s2++ = rule_table[ruleno].lhs;
+             }
          }
       }