Infrastructure for deducing Param types from context, in the same way

that the types of untyped string-literal constants are deduced (ie,
when coerce_type is applied to 'em, that's what the type must be).
Remove the ancient hack of storing the input Param-types array as a
global variable, and put the info into ParseState instead.  This touches
a lot of files because of adjustment of routine parameter lists, but
it's really not a large patch.  Note: PREPARE statement still insists on
exact specification of parameter types, but that could easily be relaxed
now, if we wanted to do so.

src/backend/optimizer/plan/subselect.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.74 2003/04/08 23:20:01 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.75 2003/04/29 22:13:09 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -495,10 +495,13 @@ convert_sublink_opers(List *lefthand, List *operOids,
 		 * Make the expression node.
 		 *
 		 * Note: we use make_op_expr in case runtime type conversion
-		 * function calls must be inserted for this operator!
+		 * function calls must be inserted for this operator!  (But we
+		 * are not expecting to have to resolve unknown Params, so
+		 * it's okay to pass a null pstate.)
 		 */
 		result = lappend(result,
-						 make_op_expr(tup,
+						 make_op_expr(NULL,
+									  tup,
 									  leftop,
 									  rightop,
 									  exprType(leftop),