The computation of nullable is broken: it doesn't handle empty

[bison.git] / src / reduce.c

diff --git a/src/reduce.c b/src/reduce.c
index 87a2a1a977148c2e15eac43e99cd5d04f86f6960..d8ea5ed60ba1f95327219cdc8cf51db90e6f10a1 100644 (file)
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -264,28 +264,35 @@ inaccessable_symbols (void)
 static void
 reduce_grammar_tables (void)
 {
-/* This is turned off because we would need to change the numbers
-   in the case statements in the actions file.  */
-#if 0
-  /* remove useless productions */
-  if (nuseless_productions > 0)
-    {
-      short np, pn, ni, pi;
+  /* This is turned off because we would need to change the numbers in
+     the case statements in the actions file.
 
-      np = 0;
-      ni = 0;
-      for (pn = 1; pn <= nrules; pn++)
-       {
+     We don't disable it via CPP so that it is still checked with the
+     rest of the code, to avoid its becoming completely obsolete.
+
+     FIXME: I think the comment above demonstrates this code must be
+     turned off for *semantic* parser, not in the general case.  Try
+     to understand this better --akim.  */
+
+  if (0)
+    /* remove useless productions */
+    if (nuseless_productions > 0)
+      {
+       short np, pn, ni, pi;
+
+       np = 0;
+       ni = 0;
+       for (pn = 1; pn <= nrules; pn++)
          if (BITISSET (P, pn))
            {
              np++;
              if (pn != np)
                {
-                 rule_table[np].lhs = rule_table[pn].lhs;
-                 rline[np] = rline[pn];
-                 rule_table[np].prec = rule_table[pn].prec;
+                 rule_table[np].lhs   = rule_table[pn].lhs;
+                 rule_table[np].line  = rule_table[pn].line;
+                 rule_table[np].prec  = rule_table[pn].prec;
                  rule_table[np].assoc = rule_table[pn].assoc;
-                 rule_table[np].rhs = rule_table[pn].rhs;
+                 rule_table[np].rhs   = rule_table[pn].rhs;
                  if (rule_table[np].rhs != ni)
                    {
                      pi = rule_table[np].rhs;
@@ -300,16 +307,15 @@ reduce_grammar_tables (void)
                  while (ritem[ni++] >= 0);
                }
            }
-       }
-      ritem[ni] = 0;
-      nrules -= nuseless_productions;
-      nitems = ni;
 
-      /* Is it worth it to reduce the amount of memory for the
-         grammar? Probably not.  */
+       ritem[ni] = 0;
+       nrules -= nuseless_productions;
+       nitems = ni;
+
+       /* Is it worth it to reduce the amount of memory for the
+          grammar? Probably not.  */
+      }
 
-    }
-#endif /* 0 */
   /* Disable useless productions. */
   if (nuseless_productions > 0)
     {