+ if (!prec_nodes)
+ init_prec_nodes ();
+ register_precedence_second_symbol (&(prec_nodes[first]->succ), snd);
+ register_precedence_second_symbol (&(prec_nodes[snd]->pred), first);
+}
+
+
+/*---------------------------------------.
+| Initialize association tracking table. |
+`---------------------------------------*/
+
+static void
+init_assoc (void)
+{
+ graphid i;
+ used_assoc = xcalloc(nsyms, sizeof(*used_assoc));
+ for (i = 0; i < nsyms; ++i)
+ used_assoc[i] = false;
+}
+
+/*------------------------------------------------------------------.
+| Test if the associativity for the symbols is defined and useless. |
+`------------------------------------------------------------------*/
+
+static inline bool
+is_assoc_useless (symbol *s)
+{
+ return s
+ && s->assoc != undef_assoc
+ && s->assoc != precedence_assoc
+ && !used_assoc[s->number];
+}
+
+/*-------------------------------.
+| Register a used associativity. |
+`-------------------------------*/
+
+void
+register_assoc (graphid i, graphid j)
+{
+ if (!used_assoc)
+ init_assoc ();
+ used_assoc[i] = true;
+ used_assoc[j] = true;
+}
+
+/*--------------------------------------------------.
+| Print a warning for unused precedence relations. |
+`--------------------------------------------------*/
+
+void
+print_precedence_warnings (void)
+{
+ int i;
+ if (!prec_nodes)
+ init_prec_nodes ();
+ if (!used_assoc)
+ init_assoc ();
+ for (i = 0; i < nsyms; ++i)