Fix up the remaining places where the expression node structure would lose

available information about the typmod of an expression; namely, Const,
ArrayRef, ArrayExpr, and EXPR and ARRAY SubLinks.  In the ArrayExpr and
SubLink cases it wasn't really the data structure's fault, but exprTypmod()
being lazy.  This seems like a good idea in view of the expected increase in
typmod usage from Teodor's work to allow user-defined types to have typmods.
In particular this responds to the concerns we had about eliminating the
special-purpose hack that exprTypmod() used to have for BPCHAR Consts.
We can now tell whether or not such a Const has been cast to a specific
length, and report or display properly if so.

initdb forced due to changes in stored rules.

src/backend/utils/cache/lsyscache.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.148 2007/02/14 01:58:57 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.149 2007/03/17 00:11:05 tgl Exp $
  *
  * NOTES
  *	  Eventually, the index information should go through here, too.
@@ -1964,6 +1964,7 @@ get_typdefault(Oid typid)
 										 getTypeIOParam(typeTuple), -1);
 			/* Build a Const node containing the value */
 			expr = (Node *) makeConst(typid,
+									  -1,
 									  type->typlen,
 									  datum,
 									  false,