Modify processing of DECLARE CURSOR and EXPLAIN so that they can resolve the

types of unspecified parameters when submitted via extended query protocol.
This worked in 8.2 but I had broken it during plancache changes.  DECLARE
CURSOR is now treated almost exactly like a plain SELECT through parse
analysis, rewrite, and planning; only just before sending to the executor
do we divert it away to ProcessUtility.  This requires a special-case check
in a number of places, but practically all of them were already special-casing
SELECT INTO, so it's not too ugly.  (Maybe it would be a good idea to merge
the two by treating IntoClause as a form of utility statement?  Not going to
worry about that now, though.)  That approach doesn't work for EXPLAIN,
however, so for that I punted and used a klugy solution of running parse
analysis an extra time if under extended query protocol.

src/backend/optimizer/plan/planagg.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.31 2007/04/21 21:01:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.32 2007/04/27 22:05:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -454,7 +454,8 @@ make_agg_subplan(PlannerInfo *root, MinMaxAggInfo *info)
 	subparse->commandType = CMD_SELECT;
 	subparse->resultRelation = 0;
 	subparse->returningList = NIL;
-	subparse->into = NULL;
+	subparse->utilityStmt = NULL;
+	subparse->intoClause = NULL;
 	subparse->hasAggs = false;
 	subparse->groupClause = NIL;
 	subparse->havingQual = NULL;

src/backend/optimizer/plan/planner.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.217 2007/04/16 01:14:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.218 2007/04/27 22:05:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -90,6 +90,11 @@ planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	ListCell   *lp,
 			   *lr;
 
+	/* Cursor options may come from caller or from DECLARE CURSOR stmt */
+	if (parse->utilityStmt &&
+		IsA(parse->utilityStmt, DeclareCursorStmt))
+		cursorOptions |= ((DeclareCursorStmt *) parse->utilityStmt)->options;
+
 	/*
 	 * Set up global state for this planner invocation.  This data is needed
 	 * across all levels of sub-Query that might exist in the given command,
@@ -156,7 +161,8 @@ planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	result->planTree = top_plan;
 	result->rtable = glob->finalrtable;
 	result->resultRelations = root->resultRelations;
-	result->into = parse->into;
+	result->utilityStmt = parse->utilityStmt;
+	result->intoClause = parse->intoClause;
 	result->subplans = glob->subplans;
 	result->rewindPlanIDs = glob->rewindPlanIDs;
 	result->returningLists = root->returningLists;

src/backend/optimizer/prep/prepjointree.c

@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.47 2007/02/19 07:03:30 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.48 2007/04/27 22:05:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -627,7 +627,8 @@ is_simple_subquery(Query *subquery)
 	 */
 	if (!IsA(subquery, Query) ||
 		subquery->commandType != CMD_SELECT ||
-		subquery->into != NULL)
+		subquery->utilityStmt != NULL ||
+		subquery->intoClause != NULL)
 		elog(ERROR, "subquery is bogus");
 
 	/*
@@ -698,7 +699,8 @@ is_simple_union_all(Query *subquery)
 	/* Let's just make sure it's a valid subselect ... */
 	if (!IsA(subquery, Query) ||
 		subquery->commandType != CMD_SELECT ||
-		subquery->into != NULL)
+		subquery->utilityStmt != NULL ||
+		subquery->intoClause != NULL)
 		elog(ERROR, "subquery is bogus");
 
 	/* Is it a set-operation query at all? */

src/backend/optimizer/util/clauses.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.241 2007/04/02 03:49:38 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.242 2007/04/27 22:05:48 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -2945,7 +2945,8 @@ inline_function(Oid funcid, Oid result_type, List *args,
 	 */
 	if (!IsA(querytree, Query) ||
 		querytree->commandType != CMD_SELECT ||
-		querytree->into ||
+		querytree->utilityStmt ||
+		querytree->intoClause ||
 		querytree->hasAggs ||
 		querytree->hasSubLinks ||
 		querytree->rtable ||