Don't try to constant-fold functions returning RECORD, since the optimizer

isn't presently set up to pass them an expected tuple descriptor.  Bug has
been there since 7.3 but was just recently reported by Thomas Hallgren.

src/backend/optimizer/util/clauses.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.194 2005/04/10 20:57:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.195 2005/04/14 21:44:09 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -19,6 +19,7 @@
 
 #include "postgres.h"
 
+#include "access/heapam.h"
 #include "catalog/pg_aggregate.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_operator.h"
@@ -2103,6 +2104,16 @@ evaluate_function(Oid funcid, Oid result_type, List *args,
 	if (funcform->proretset)
 		return NULL;
 
+	/*
+	 * Can't simplify if it returns RECORD, except in the case where it has
+	 * OUT parameters, since it will be needing an expected tupdesc which we
+	 * can't supply here.
+	 */
+	if (funcform->prorettype == RECORDOID &&
+		(heap_attisnull(func_tuple, Anum_pg_proc_proallargtypes) ||
+		 heap_attisnull(func_tuple, Anum_pg_proc_proargmodes)))
+		return NULL;
+
 	/*
 	 * Check for constant inputs and especially constant-NULL inputs.
 	 */