Tweak generic_type_consistency routines to avoid loss of functionality

since 7.3: 'select array_dims(histogram_bounds) from pg_stats' used to
work and still should.  Problem was that code wouldn't take input of
declared type anyarray as matching an anyarray argument.  Allow this
case as long as we don't need to determine an element type (which in
practice means as long as anyelement isn't used in the function signature).

src/backend/parser/parse_coerce.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.108 2003/08/04 02:40:01 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.109 2003/09/23 17:12:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -762,6 +762,12 @@ coerce_to_common_type(ParseState *pstate, Node *node,
  * If we have UNKNOWN input (ie, an untyped literal) for any ANYELEMENT
  * or ANYARRAY argument, assume it is okay.
  *
+ * If an input is of type ANYARRAY (ie, we know it's an array, but not
+ * what element type), we will accept it as a match to an argument declared
+ * ANYARRAY, so long as we don't have to determine an element type ---
+ * that is, so long as there is no use of ANYELEMENT.  This is mostly for
+ * backwards compatibility with the pre-7.4 behavior of ANYARRAY.
+ *
  * We do not ereport here, but just return FALSE if a rule is violated.
  */
 bool
@@ -773,6 +779,7 @@ check_generic_type_consistency(Oid *actual_arg_types,
 	Oid			elem_typeid = InvalidOid;
 	Oid			array_typeid = InvalidOid;
 	Oid			array_typelem;
+	bool		have_anyelement = false;
 
 	/*
 	 * Loop through the arguments to see if we have any that are ANYARRAY
@@ -785,6 +792,7 @@ check_generic_type_consistency(Oid *actual_arg_types,
 
 		if (declared_arg_types[j] == ANYELEMENTOID)
 		{
+			have_anyelement = true;
 			if (actual_type == UNKNOWNOID)
 				continue;
 			if (OidIsValid(elem_typeid) && actual_type != elem_typeid)
@@ -804,6 +812,14 @@ check_generic_type_consistency(Oid *actual_arg_types,
 	/* Get the element type based on the array type, if we have one */
 	if (OidIsValid(array_typeid))
 	{
+		if (array_typeid == ANYARRAYOID)
+		{
+			/* Special case for ANYARRAY input: okay iff no ANYELEMENT */
+			if (have_anyelement)
+				return false;
+			return true;
+		}
+
 		array_typelem = get_element_type(array_typeid);
 		if (!OidIsValid(array_typelem))
 			return false;		/* should be an array, but isn't */
@@ -875,7 +891,8 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 	bool		have_unknowns = false;
 	Oid			elem_typeid = InvalidOid;
 	Oid			array_typeid = InvalidOid;
-	Oid			array_typelem = InvalidOid;
+	Oid			array_typelem;
+	bool		have_anyelement = (rettype == ANYELEMENTOID);
 
 	/*
 	 * Loop through the arguments to see if we have any that are ANYARRAY
@@ -888,7 +905,7 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 
 		if (declared_arg_types[j] == ANYELEMENTOID)
 		{
-			have_generics = true;
+			have_generics = have_anyelement = true;
 			if (actual_type == UNKNOWNOID)
 			{
 				have_unknowns = true;
@@ -932,12 +949,20 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 	/* Get the element type based on the array type, if we have one */
 	if (OidIsValid(array_typeid))
 	{
-		array_typelem = get_element_type(array_typeid);
-		if (!OidIsValid(array_typelem))
-			ereport(ERROR,
-					(errcode(ERRCODE_DATATYPE_MISMATCH),
-			  errmsg("argument declared ANYARRAY is not an array but %s",
-					 format_type_be(array_typeid))));
+		if (array_typeid == ANYARRAYOID && !have_anyelement)
+		{
+			/* Special case for ANYARRAY input: okay iff no ANYELEMENT */
+			array_typelem = InvalidOid;
+		}
+		else
+		{
+			array_typelem = get_element_type(array_typeid);
+			if (!OidIsValid(array_typelem))
+				ereport(ERROR,
+						(errcode(ERRCODE_DATATYPE_MISMATCH),
+						 errmsg("argument declared ANYARRAY is not an array but %s",
+								format_type_be(array_typeid))));
+		}
 
 		if (!OidIsValid(elem_typeid))
 		{