Add optional "validator" function to languages that can validate the

function body (and other properties) as a function in the language
is created.  This generalizes ad hoc code that already existed for
the built-in languages.

The validation now happens after the pg_proc tuple of the new function
is created, so it is possible to define recursive SQL functions.

Add some regression test cases that cover bogus function definition
attempts.

src/backend/utils/adt/sets.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/Attic/sets.c,v 1.44 2002/05/18 13:47:59 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/Attic/sets.c,v 1.45 2002/05/22 17:21:00 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -58,6 +58,7 @@ SetDefine(char *querystr, Oid elemType)
 							 true,		/* returnsSet */
 							 elemType,	/* returnType */
 							 SQLlanguageId,	/* language */
+							 SQLvalidatorId,
 							 querystr,	/* prosrc */
 							 fileName,	/* probin */
 							 false,		/* not aggregate */