Allow binary-coercible cases in ri_HashCompareOp; there are some such cases

that are not handled by find_coercion_pathway, notably composite->RECORD.
Now that 8.4 supports composites as primary keys, it's worth dealing with
this case.

src/backend/utils/adt/ri_triggers.c

@@ -15,7 +15,7 @@
  *
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/ri_triggers.c,v 1.114 2009/08/01 19:59:41 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/ri_triggers.c,v 1.115 2009/11/05 04:38:29 tgl Exp $
  *
  * ----------
  */
@@ -3963,10 +3963,12 @@ ri_HashCompareOp(Oid eq_opr, Oid typeid)
 			{
 				/*
 				 * The declared input type of the eq_opr might be a
-				 * polymorphic type such as ANYARRAY or ANYENUM.  If so,
-				 * assume the coercion is valid; otherwise complain.
+				 * polymorphic type such as ANYARRAY or ANYENUM, or other
+				 * special cases such as RECORD; find_coercion_pathway
+				 * currently doesn't subsume these special cases.
 				 */
-				if (!IsPolymorphicType(lefttype))
+				if (!IsPolymorphicType(lefttype) &&
+					!IsBinaryCoercible(typeid, lefttype))
 					elog(ERROR, "no conversion function from %s to %s",
 						 format_type_be(typeid),
 						 format_type_be(lefttype));