/*-------------------------------------------------------------------------
 *
 * parse_expr.c
 *	  handle expressions in parser
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/parser/parse_expr.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "catalog/pg_aggregate.h"
#include "catalog/pg_type.h"
#include "commands/dbcommands.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/optimizer.h"
#include "parser/analyze.h"
#include "parser/parse_agg.h"
#include "parser/parse_clause.h"
#include "parser/parse_coerce.h"
#include "parser/parse_collate.h"
#include "parser/parse_expr.h"
#include "parser/parse_func.h"
#include "parser/parse_oper.h"
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
#include "parser/parse_type.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/timestamp.h"
#include "utils/xml.h"

/* GUC parameters */
bool		Transform_null_equals = false;


static Node *transformExprRecurse(ParseState *pstate, Node *expr);
static Node *transformParamRef(ParseState *pstate, ParamRef *pref);
static Node *transformAExprOp(ParseState *pstate, A_Expr *a);
static Node *transformAExprOpAny(ParseState *pstate, A_Expr *a);
static Node *transformAExprOpAll(ParseState *pstate, A_Expr *a);
static Node *transformAExprDistinct(ParseState *pstate, A_Expr *a);
static Node *transformAExprNullIf(ParseState *pstate, A_Expr *a);
static Node *transformAExprIn(ParseState *pstate, A_Expr *a);
static Node *transformAExprBetween(ParseState *pstate, A_Expr *a);
static Node *transformMergeSupportFunc(ParseState *pstate, MergeSupportFunc *f);
static Node *transformBoolExpr(ParseState *pstate, BoolExpr *a);
static Node *transformFuncCall(ParseState *pstate, FuncCall *fn);
static Node *transformMultiAssignRef(ParseState *pstate, MultiAssignRef *maref);
static Node *transformCaseExpr(ParseState *pstate, CaseExpr *c);
static Node *transformSubLink(ParseState *pstate, SubLink *sublink);
static Node *transformArrayExpr(ParseState *pstate, A_ArrayExpr *a,
								Oid array_type, Oid element_type, int32 typmod);
static Node *transformRowExpr(ParseState *pstate, RowExpr *r, bool allowDefault);
static Node *transformCoalesceExpr(ParseState *pstate, CoalesceExpr *c);
static Node *transformMinMaxExpr(ParseState *pstate, MinMaxExpr *m);
static Node *transformSQLValueFunction(ParseState *pstate,
									   SQLValueFunction *svf);
static Node *transformXmlExpr(ParseState *pstate, XmlExpr *x);
static Node *transformXmlSerialize(ParseState *pstate, XmlSerialize *xs);
static Node *transformBooleanTest(ParseState *pstate, BooleanTest *b);
static Node *transformCurrentOfExpr(ParseState *pstate, CurrentOfExpr *cexpr);
static Node *transformColumnRef(ParseState *pstate, ColumnRef *cref);
static Node *transformWholeRowRef(ParseState *pstate,
								  ParseNamespaceItem *nsitem,
								  int sublevels_up, int location);
static Node *transformIndirection(ParseState *pstate, A_Indirection *ind);
static Node *transformTypeCast(ParseState *pstate, TypeCast *tc);
static Node *transformCollateClause(ParseState *pstate, CollateClause *c);
static Node *transformJsonObjectConstructor(ParseState *pstate,
											JsonObjectConstructor *ctor);
static Node *transformJsonArrayConstructor(ParseState *pstate,
										   JsonArrayConstructor *ctor);
static Node *transformJsonArrayQueryConstructor(ParseState *pstate,
												JsonArrayQueryConstructor *ctor);
static Node *transformJsonObjectAgg(ParseState *pstate, JsonObjectAgg *agg);
static Node *transformJsonArrayAgg(ParseState *pstate, JsonArrayAgg *agg);
static Node *transformJsonIsPredicate(ParseState *pstate, JsonIsPredicate *pred);
static Node *transformJsonParseExpr(ParseState *pstate, JsonParseExpr *jsexpr);
static Node *transformJsonScalarExpr(ParseState *pstate, JsonScalarExpr *jsexpr);
static Node *transformJsonSerializeExpr(ParseState *pstate,
										JsonSerializeExpr *expr);
static Node *transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func);
static void transformJsonPassingArgs(ParseState *pstate, const char *constructName,
									 JsonFormatType format, List *args,
									 List **passing_values, List **passing_names);
static JsonBehavior *transformJsonBehavior(ParseState *pstate, JsonExpr *jsexpr,
										   JsonBehavior *behavior,
										   JsonBehaviorType default_behavior,
										   JsonReturning *returning);
static Node *GetJsonBehaviorConst(JsonBehaviorType btype, int location);
static Node *make_row_comparison_op(ParseState *pstate, List *opname,
									List *largs, List *rargs, int location);
static Node *make_row_distinct_op(ParseState *pstate, List *opname,
								  RowExpr *lrow, RowExpr *rrow, int location);
static Expr *make_distinct_op(ParseState *pstate, List *opname,
							  Node *ltree, Node *rtree, int location);
static Node *make_nulltest_from_distinct(ParseState *pstate,
										 A_Expr *distincta, Node *arg);


/*
 * transformExpr -
 *	  Analyze and transform expressions. Type checking and type casting is
 *	  done here.  This processing converts the raw grammar output into
 *	  expression trees with fully determined semantics.
 */
Node *
transformExpr(ParseState *pstate, Node *expr, ParseExprKind exprKind)
{
	Node	   *result;
	ParseExprKind sv_expr_kind;

	/* Save and restore identity of expression type we're parsing */
	Assert(exprKind != EXPR_KIND_NONE);
	sv_expr_kind = pstate->p_expr_kind;
	pstate->p_expr_kind = exprKind;

	result = transformExprRecurse(pstate, expr);

	pstate->p_expr_kind = sv_expr_kind;

	return result;
}

static Node *
transformExprRecurse(ParseState *pstate, Node *expr)
{
	Node	   *result;

	if (expr == NULL)
		return NULL;

	/* Guard against stack overflow due to overly complex expressions */
	check_stack_depth();

	switch (nodeTag(expr))
	{
		case T_ColumnRef:
			result = transformColumnRef(pstate, (ColumnRef *) expr);
			break;

		case T_ParamRef:
			result = transformParamRef(pstate, (ParamRef *) expr);
			break;

		case T_A_Const:
			result = (Node *) make_const(pstate, (A_Const *) expr);
			break;

		case T_A_Indirection:
			result = transformIndirection(pstate, (A_Indirection *) expr);
			break;

		case T_A_ArrayExpr:
			result = transformArrayExpr(pstate, (A_ArrayExpr *) expr,
										InvalidOid, InvalidOid, -1);
			break;

		case T_TypeCast:
			result = transformTypeCast(pstate, (TypeCast *) expr);
			break;

		case T_CollateClause:
			result = transformCollateClause(pstate, (CollateClause *) expr);
			break;

		case T_A_Expr:
			{
				A_Expr	   *a = (A_Expr *) expr;

				switch (a->kind)
				{
					case AEXPR_OP:
						result = transformAExprOp(pstate, a);
						break;
					case AEXPR_OP_ANY:
						result = transformAExprOpAny(pstate, a);
						break;
					case AEXPR_OP_ALL:
						result = transformAExprOpAll(pstate, a);
						break;
					case AEXPR_DISTINCT:
					case AEXPR_NOT_DISTINCT:
						result = transformAExprDistinct(pstate, a);
						break;
					case AEXPR_NULLIF:
						result = transformAExprNullIf(pstate, a);
						break;
					case AEXPR_IN:
						result = transformAExprIn(pstate, a);
						break;
					case AEXPR_LIKE:
					case AEXPR_ILIKE:
					case AEXPR_SIMILAR:
						/* we can transform these just like AEXPR_OP */
						result = transformAExprOp(pstate, a);
						break;
					case AEXPR_BETWEEN:
					case AEXPR_NOT_BETWEEN:
					case AEXPR_BETWEEN_SYM:
					case AEXPR_NOT_BETWEEN_SYM:
						result = transformAExprBetween(pstate, a);
						break;
					default:
						elog(ERROR, "unrecognized A_Expr kind: %d", a->kind);
						result = NULL;	/* keep compiler quiet */
						break;
				}
				break;
			}

		case T_BoolExpr:
			result = transformBoolExpr(pstate, (BoolExpr *) expr);
			break;

		case T_FuncCall:
			result = transformFuncCall(pstate, (FuncCall *) expr);
			break;

		case T_MultiAssignRef:
			result = transformMultiAssignRef(pstate, (MultiAssignRef *) expr);
			break;

		case T_GroupingFunc:
			result = transformGroupingFunc(pstate, (GroupingFunc *) expr);
			break;

		case T_MergeSupportFunc:
			result = transformMergeSupportFunc(pstate,
											   (MergeSupportFunc *) expr);
			break;

		case T_NamedArgExpr:
			{
				NamedArgExpr *na = (NamedArgExpr *) expr;

				na->arg = (Expr *) transformExprRecurse(pstate, (Node *) na->arg);
				result = expr;
				break;
			}

		case T_SubLink:
			result = transformSubLink(pstate, (SubLink *) expr);
			break;

		case T_CaseExpr:
			result = transformCaseExpr(pstate, (CaseExpr *) expr);
			break;

		case T_RowExpr:
			result = transformRowExpr(pstate, (RowExpr *) expr, false);
			break;

		case T_CoalesceExpr:
			result = transformCoalesceExpr(pstate, (CoalesceExpr *) expr);
			break;

		case T_MinMaxExpr:
			result = transformMinMaxExpr(pstate, (MinMaxExpr *) expr);
			break;

		case T_SQLValueFunction:
			result = transformSQLValueFunction(pstate,
											   (SQLValueFunction *) expr);
			break;

		case T_XmlExpr:
			result = transformXmlExpr(pstate, (XmlExpr *) expr);
			break;

		case T_XmlSerialize:
			result = transformXmlSerialize(pstate, (XmlSerialize *) expr);
			break;

		case T_NullTest:
			{
				NullTest   *n = (NullTest *) expr;

				n->arg = (Expr *) transformExprRecurse(pstate, (Node *) n->arg);
				/* the argument can be any type, so don't coerce it */
				n->argisrow = type_is_rowtype(exprType((Node *) n->arg));
				result = expr;
				break;
			}

		case T_BooleanTest:
			result = transformBooleanTest(pstate, (BooleanTest *) expr);
			break;

		case T_CurrentOfExpr:
			result = transformCurrentOfExpr(pstate, (CurrentOfExpr *) expr);
			break;

			/*
			 * In all places where DEFAULT is legal, the caller should have
			 * processed it rather than passing it to transformExpr().
			 */
		case T_SetToDefault:
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("DEFAULT is not allowed in this context"),
					 parser_errposition(pstate,
										((SetToDefault *) expr)->location)));
			break;

			/*
			 * CaseTestExpr doesn't require any processing; it is only
			 * injected into parse trees in a fully-formed state.
			 *
			 * Ordinarily we should not see a Var here, but it is convenient
			 * for transformJoinUsingClause() to create untransformed operator
			 * trees containing already-transformed Vars.  The best
			 * alternative would be to deconstruct and reconstruct column
			 * references, which seems expensively pointless.  So allow it.
			 */
		case T_CaseTestExpr:
		case T_Var:
			{
				result = (Node *) expr;
				break;
			}

		case T_JsonObjectConstructor:
			result = transformJsonObjectConstructor(pstate, (JsonObjectConstructor *) expr);
			break;

		case T_JsonArrayConstructor:
			result = transformJsonArrayConstructor(pstate, (JsonArrayConstructor *) expr);
			break;

		case T_JsonArrayQueryConstructor:
			result = transformJsonArrayQueryConstructor(pstate, (JsonArrayQueryConstructor *) expr);
			break;

		case T_JsonObjectAgg:
			result = transformJsonObjectAgg(pstate, (JsonObjectAgg *) expr);
			break;

		case T_JsonArrayAgg:
			result = transformJsonArrayAgg(pstate, (JsonArrayAgg *) expr);
			break;

		case T_JsonIsPredicate:
			result = transformJsonIsPredicate(pstate, (JsonIsPredicate *) expr);
			break;

		case T_JsonParseExpr:
			result = transformJsonParseExpr(pstate, (JsonParseExpr *) expr);
			break;

		case T_JsonScalarExpr:
			result = transformJsonScalarExpr(pstate, (JsonScalarExpr *) expr);
			break;

		case T_JsonSerializeExpr:
			result = transformJsonSerializeExpr(pstate, (JsonSerializeExpr *) expr);
			break;

		case T_JsonFuncExpr:
			result = transformJsonFuncExpr(pstate, (JsonFuncExpr *) expr);
			break;

		default:
			/* should not reach here */
			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
			result = NULL;		/* keep compiler quiet */
			break;
	}

	return result;
}

/*
 * helper routine for delivering "column does not exist" error message
 *
 * (Usually we don't have to work this hard, but the general case of field
 * selection from an arbitrary node needs it.)
 */
static void
unknown_attribute(ParseState *pstate, Node *relref, const char *attname,
				  int location)
{
	RangeTblEntry *rte;

	if (IsA(relref, Var) &&
		((Var *) relref)->varattno == InvalidAttrNumber)
	{
		/* Reference the RTE by alias not by actual table name */
		rte = GetRTEByRangeTablePosn(pstate,
									 ((Var *) relref)->varno,
									 ((Var *) relref)->varlevelsup);
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_COLUMN),
				 errmsg("column %s.%s does not exist",
						rte->eref->aliasname, attname),
				 parser_errposition(pstate, location)));
	}
	else
	{
		/* Have to do it by reference to the type of the expression */
		Oid			relTypeId = exprType(relref);

		if (ISCOMPLEX(relTypeId))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_COLUMN),
					 errmsg("column \"%s\" not found in data type %s",
							attname, format_type_be(relTypeId)),
					 parser_errposition(pstate, location)));
		else if (relTypeId == RECORDOID)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_COLUMN),
					 errmsg("could not identify column \"%s\" in record data type",
							attname),
					 parser_errposition(pstate, location)));
		else
			ereport(ERROR,
					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
					 errmsg("column notation .%s applied to type %s, "
							"which is not a composite type",
							attname, format_type_be(relTypeId)),
					 parser_errposition(pstate, location)));
	}
}

static Node *
transformIndirection(ParseState *pstate, A_Indirection *ind)
{
	Node	   *last_srf = pstate->p_last_srf;
	Node	   *result = transformExprRecurse(pstate, ind->arg);
	List	   *subscripts = NIL;
	int			location = exprLocation(result);
	ListCell   *i;

	/*
	 * We have to split any field-selection operations apart from
	 * subscripting.  Adjacent A_Indices nodes have to be treated as a single
	 * multidimensional subscript operation.
	 */
	foreach(i, ind->indirection)
	{
		Node	   *n = lfirst(i);

		if (IsA(n, A_Indices))
			subscripts = lappend(subscripts, n);
		else if (IsA(n, A_Star))
		{
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("row expansion via \"*\" is not supported here"),
					 parser_errposition(pstate, location)));
		}
		else
		{
			Node	   *newresult;

			Assert(IsA(n, String));

			/* process subscripts before this field selection */
			if (subscripts)
				result = (Node *) transformContainerSubscripts(pstate,
															   result,
															   exprType(result),
															   exprTypmod(result),
															   subscripts,
															   false);
			subscripts = NIL;

			newresult = ParseFuncOrColumn(pstate,
										  list_make1(n),
										  list_make1(result),
										  last_srf,
										  NULL,
										  false,
										  location);
			if (newresult == NULL)
				unknown_attribute(pstate, result, strVal(n), location);
			result = newresult;
		}
	}
	/* process trailing subscripts, if any */
	if (subscripts)
		result = (Node *) transformContainerSubscripts(pstate,
													   result,
													   exprType(result),
													   exprTypmod(result),
													   subscripts,
													   false);

	return result;
}

/*
 * Transform a ColumnRef.
 *
 * If you find yourself changing this code, see also ExpandColumnRefStar.
 */
static Node *
transformColumnRef(ParseState *pstate, ColumnRef *cref)
{
	Node	   *node = NULL;
	char	   *nspname = NULL;
	char	   *relname = NULL;
	char	   *colname = NULL;
	ParseNamespaceItem *nsitem;
	int			levels_up;
	enum
	{
		CRERR_NO_COLUMN,
		CRERR_NO_RTE,
		CRERR_WRONG_DB,
		CRERR_TOO_MANY
	}			crerr = CRERR_NO_COLUMN;
	const char *err;

	/*
	 * Check to see if the column reference is in an invalid place within the
	 * query.  We allow column references in most places, except in default
	 * expressions and partition bound expressions.
	 */
	err = NULL;
	switch (pstate->p_expr_kind)
	{
		case EXPR_KIND_NONE:
			Assert(false);		/* can't happen */
			break;
		case EXPR_KIND_OTHER:
		case EXPR_KIND_JOIN_ON:
		case EXPR_KIND_JOIN_USING:
		case EXPR_KIND_FROM_SUBSELECT:
		case EXPR_KIND_FROM_FUNCTION:
		case EXPR_KIND_WHERE:
		case EXPR_KIND_POLICY:
		case EXPR_KIND_HAVING:
		case EXPR_KIND_FILTER:
		case EXPR_KIND_WINDOW_PARTITION:
		case EXPR_KIND_WINDOW_ORDER:
		case EXPR_KIND_WINDOW_FRAME_RANGE:
		case EXPR_KIND_WINDOW_FRAME_ROWS:
		case EXPR_KIND_WINDOW_FRAME_GROUPS:
		case EXPR_KIND_SELECT_TARGET:
		case EXPR_KIND_INSERT_TARGET:
		case EXPR_KIND_UPDATE_SOURCE:
		case EXPR_KIND_UPDATE_TARGET:
		case EXPR_KIND_MERGE_WHEN:
		case EXPR_KIND_GROUP_BY:
		case EXPR_KIND_ORDER_BY:
		case EXPR_KIND_DISTINCT_ON:
		case EXPR_KIND_LIMIT:
		case EXPR_KIND_OFFSET:
		case EXPR_KIND_RETURNING:
		case EXPR_KIND_MERGE_RETURNING:
		case EXPR_KIND_VALUES:
		case EXPR_KIND_VALUES_SINGLE:
		case EXPR_KIND_CHECK_CONSTRAINT:
		case EXPR_KIND_DOMAIN_CHECK:
		case EXPR_KIND_FUNCTION_DEFAULT:
		case EXPR_KIND_INDEX_EXPRESSION:
		case EXPR_KIND_INDEX_PREDICATE:
		case EXPR_KIND_STATS_EXPRESSION:
		case EXPR_KIND_ALTER_COL_TRANSFORM:
		case EXPR_KIND_EXECUTE_PARAMETER:
		case EXPR_KIND_TRIGGER_WHEN:
		case EXPR_KIND_PARTITION_EXPRESSION:
		case EXPR_KIND_CALL_ARGUMENT:
		case EXPR_KIND_COPY_WHERE:
		case EXPR_KIND_GENERATED_COLUMN:
		case EXPR_KIND_CYCLE_MARK:
			/* okay */
			break;

		case EXPR_KIND_COLUMN_DEFAULT:
			err = _("cannot use column reference in DEFAULT expression");
			break;
		case EXPR_KIND_PARTITION_BOUND:
			err = _("cannot use column reference in partition bound expression");
			break;

			/*
			 * There is intentionally no default: case here, so that the
			 * compiler will warn if we add a new ParseExprKind without
			 * extending this switch.  If we do see an unrecognized value at
			 * runtime, the behavior will be the same as for EXPR_KIND_OTHER,
			 * which is sane anyway.
			 */
	}
	if (err)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg_internal("%s", err),
				 parser_errposition(pstate, cref->location)));

	/*
	 * Give the PreParseColumnRefHook, if any, first shot.  If it returns
	 * non-null then that's all, folks.
	 */
	if (pstate->p_pre_columnref_hook != NULL)
	{
		node = pstate->p_pre_columnref_hook(pstate, cref);
		if (node != NULL)
			return node;
	}

	/*----------
	 * The allowed syntaxes are:
	 *
	 * A		First try to resolve as unqualified column name;
	 *			if no luck, try to resolve as unqualified table name (A.*).
	 * A.B		A is an unqualified table name; B is either a
	 *			column or function name (trying column name first).
	 * A.B.C	schema A, table B, col or func name C.
	 * A.B.C.D	catalog A, schema B, table C, col or func D.
	 * A.*		A is an unqualified table name; means whole-row value.
	 * A.B.*	whole-row value of table B in schema A.
	 * A.B.C.*	whole-row value of table C in schema B in catalog A.
	 *
	 * We do not need to cope with bare "*"; that will only be accepted by
	 * the grammar at the top level of a SELECT list, and transformTargetList
	 * will take care of it before it ever gets here.  Also, "A.*" etc will
	 * be expanded by transformTargetList if they appear at SELECT top level,
	 * so here we are only going to see them as function or operator inputs.
	 *
	 * Currently, if a catalog name is given then it must equal the current
	 * database name; we check it here and then discard it.
	 *----------
	 */
	switch (list_length(cref->fields))
	{
		case 1:
			{
				Node	   *field1 = (Node *) linitial(cref->fields);

				colname = strVal(field1);

				/* Try to identify as an unqualified column */
				node = colNameToVar(pstate, colname, false, cref->location);

				if (node == NULL)
				{
					/*
					 * Not known as a column of any range-table entry.
					 *
					 * Try to find the name as a relation.  Note that only
					 * relations already entered into the rangetable will be
					 * recognized.
					 *
					 * This is a hack for backwards compatibility with
					 * PostQUEL-inspired syntax.  The preferred form now is
					 * "rel.*".
					 */
					nsitem = refnameNamespaceItem(pstate, NULL, colname,
												  cref->location,
												  &levels_up);
					if (nsitem)
						node = transformWholeRowRef(pstate, nsitem, levels_up,
													cref->location);
				}
				break;
			}
		case 2:
			{
				Node	   *field1 = (Node *) linitial(cref->fields);
				Node	   *field2 = (Node *) lsecond(cref->fields);

				relname = strVal(field1);

				/* Locate the referenced nsitem */
				nsitem = refnameNamespaceItem(pstate, nspname, relname,
											  cref->location,
											  &levels_up);
				if (nsitem == NULL)
				{
					crerr = CRERR_NO_RTE;
					break;
				}

				/* Whole-row reference? */
				if (IsA(field2, A_Star))
				{
					node = transformWholeRowRef(pstate, nsitem, levels_up,
												cref->location);
					break;
				}

				colname = strVal(field2);

				/* Try to identify as a column of the nsitem */
				node = scanNSItemForColumn(pstate, nsitem, levels_up, colname,
										   cref->location);
				if (node == NULL)
				{
					/* Try it as a function call on the whole row */
					node = transformWholeRowRef(pstate, nsitem, levels_up,
												cref->location);
					node = ParseFuncOrColumn(pstate,
											 list_make1(makeString(colname)),
											 list_make1(node),
											 pstate->p_last_srf,
											 NULL,
											 false,
											 cref->location);
				}
				break;
			}
		case 3:
			{
				Node	   *field1 = (Node *) linitial(cref->fields);
				Node	   *field2 = (Node *) lsecond(cref->fields);
				Node	   *field3 = (Node *) lthird(cref->fields);

				nspname = strVal(field1);
				relname = strVal(field2);

				/* Locate the referenced nsitem */
				nsitem = refnameNamespaceItem(pstate, nspname, relname,
											  cref->location,
											  &levels_up);
				if (nsitem == NULL)
				{
					crerr = CRERR_NO_RTE;
					break;
				}

				/* Whole-row reference? */
				if (IsA(field3, A_Star))
				{
					node = transformWholeRowRef(pstate, nsitem, levels_up,
												cref->location);
					break;
				}

				colname = strVal(field3);

				/* Try to identify as a column of the nsitem */
				node = scanNSItemForColumn(pstate, nsitem, levels_up, colname,
										   cref->location);
				if (node == NULL)
				{
					/* Try it as a function call on the whole row */
					node = transformWholeRowRef(pstate, nsitem, levels_up,
												cref->location);
					node = ParseFuncOrColumn(pstate,
											 list_make1(makeString(colname)),
											 list_make1(node),
											 pstate->p_last_srf,
											 NULL,
											 false,
											 cref->location);
				}
				break;
			}
		case 4:
			{
				Node	   *field1 = (Node *) linitial(cref->fields);
				Node	   *field2 = (Node *) lsecond(cref->fields);
				Node	   *field3 = (Node *) lthird(cref->fields);
				Node	   *field4 = (Node *) lfourth(cref->fields);
				char	   *catname;

				catname = strVal(field1);
				nspname = strVal(field2);
				relname = strVal(field3);

				/*
				 * We check the catalog name and then ignore it.
				 */
				if (strcmp(catname, get_database_name(MyDatabaseId)) != 0)
				{
					crerr = CRERR_WRONG_DB;
					break;
				}

				/* Locate the referenced nsitem */
				nsitem = refnameNamespaceItem(pstate, nspname, relname,
											  cref->location,
											  &levels_up);
				if (nsitem == NULL)
				{
					crerr = CRERR_NO_RTE;
					break;
				}

				/* Whole-row reference? */
				if (IsA(field4, A_Star))
				{
					node = transformWholeRowRef(pstate, nsitem, levels_up,
												cref->location);
					break;
				}

				colname = strVal(field4);

				/* Try to identify as a column of the nsitem */
				node = scanNSItemForColumn(pstate, nsitem, levels_up, colname,
										   cref->location);
				if (node == NULL)
				{
					/* Try it as a function call on the whole row */
					node = transformWholeRowRef(pstate, nsitem, levels_up,
												cref->location);
					node = ParseFuncOrColumn(pstate,
											 list_make1(makeString(colname)),
											 list_make1(node),
											 pstate->p_last_srf,
											 NULL,
											 false,
											 cref->location);
				}
				break;
			}
		default:
			crerr = CRERR_TOO_MANY; /* too many dotted names */
			break;
	}

	/*
	 * Now give the PostParseColumnRefHook, if any, a chance.  We pass the
	 * translation-so-far so that it can throw an error if it wishes in the
	 * case that it has a conflicting interpretation of the ColumnRef. (If it
	 * just translates anyway, we'll throw an error, because we can't undo
	 * whatever effects the preceding steps may have had on the pstate.) If it
	 * returns NULL, use the standard translation, or throw a suitable error
	 * if there is none.
	 */
	if (pstate->p_post_columnref_hook != NULL)
	{
		Node	   *hookresult;

		hookresult = pstate->p_post_columnref_hook(pstate, cref, node);
		if (node == NULL)
			node = hookresult;
		else if (hookresult != NULL)
			ereport(ERROR,
					(errcode(ERRCODE_AMBIGUOUS_COLUMN),
					 errmsg("column reference \"%s\" is ambiguous",
							NameListToString(cref->fields)),
					 parser_errposition(pstate, cref->location)));
	}

	/*
	 * Throw error if no translation found.
	 */
	if (node == NULL)
	{
		switch (crerr)
		{
			case CRERR_NO_COLUMN:
				errorMissingColumn(pstate, relname, colname, cref->location);
				break;
			case CRERR_NO_RTE:
				errorMissingRTE(pstate, makeRangeVar(nspname, relname,
													 cref->location));
				break;
			case CRERR_WRONG_DB:
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("cross-database references are not implemented: %s",
								NameListToString(cref->fields)),
						 parser_errposition(pstate, cref->location)));
				break;
			case CRERR_TOO_MANY:
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("improper qualified name (too many dotted names): %s",
								NameListToString(cref->fields)),
						 parser_errposition(pstate, cref->location)));
				break;
		}
	}

	return node;
}

static Node *
transformParamRef(ParseState *pstate, ParamRef *pref)
{
	Node	   *result;

	/*
	 * The core parser knows nothing about Params.  If a hook is supplied,
	 * call it.  If not, or if the hook returns NULL, throw a generic error.
	 */
	if (pstate->p_paramref_hook != NULL)
		result = pstate->p_paramref_hook(pstate, pref);
	else
		result = NULL;

	if (result == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_PARAMETER),
				 errmsg("there is no parameter $%d", pref->number),
				 parser_errposition(pstate, pref->location)));

	return result;
}

/* Test whether an a_expr is a plain NULL constant or not */
static bool
exprIsNullConstant(Node *arg)
{
	if (arg && IsA(arg, A_Const))
	{
		A_Const    *con = (A_Const *) arg;

		if (con->isnull)
			return true;
	}
	return false;
}

static Node *
transformAExprOp(ParseState *pstate, A_Expr *a)
{
	Node	   *lexpr = a->lexpr;
	Node	   *rexpr = a->rexpr;
	Node	   *result;

	/*
	 * Special-case "foo = NULL" and "NULL = foo" for compatibility with
	 * standards-broken products (like Microsoft's).  Turn these into IS NULL
	 * exprs. (If either side is a CaseTestExpr, then the expression was
	 * generated internally from a CASE-WHEN expression, and
	 * transform_null_equals does not apply.)
	 */
	if (Transform_null_equals &&
		list_length(a->name) == 1 &&
		strcmp(strVal(linitial(a->name)), "=") == 0 &&
		(exprIsNullConstant(lexpr) || exprIsNullConstant(rexpr)) &&
		(!IsA(lexpr, CaseTestExpr) && !IsA(rexpr, CaseTestExpr)))
	{
		NullTest   *n = makeNode(NullTest);

		n->nulltesttype = IS_NULL;
		n->location = a->location;

		if (exprIsNullConstant(lexpr))
			n->arg = (Expr *) rexpr;
		else
			n->arg = (Expr *) lexpr;

		result = transformExprRecurse(pstate, (Node *) n);
	}
	else if (lexpr && IsA(lexpr, RowExpr) &&
			 rexpr && IsA(rexpr, SubLink) &&
			 ((SubLink *) rexpr)->subLinkType == EXPR_SUBLINK)
	{
		/*
		 * Convert "row op subselect" into a ROWCOMPARE sublink. Formerly the
		 * grammar did this, but now that a row construct is allowed anywhere
		 * in expressions, it's easier to do it here.
		 */
		SubLink    *s = (SubLink *) rexpr;

		s->subLinkType = ROWCOMPARE_SUBLINK;
		s->testexpr = lexpr;
		s->operName = a->name;
		s->location = a->location;
		result = transformExprRecurse(pstate, (Node *) s);
	}
	else if (lexpr && IsA(lexpr, RowExpr) &&
			 rexpr && IsA(rexpr, RowExpr))
	{
		/* ROW() op ROW() is handled specially */
		lexpr = transformExprRecurse(pstate, lexpr);
		rexpr = transformExprRecurse(pstate, rexpr);

		result = make_row_comparison_op(pstate,
										a->name,
										castNode(RowExpr, lexpr)->args,
										castNode(RowExpr, rexpr)->args,
										a->location);
	}
	else
	{
		/* Ordinary scalar operator */
		Node	   *last_srf = pstate->p_last_srf;

		lexpr = transformExprRecurse(pstate, lexpr);
		rexpr = transformExprRecurse(pstate, rexpr);

		result = (Node *) make_op(pstate,
								  a->name,
								  lexpr,
								  rexpr,
								  last_srf,
								  a->location);
	}

	return result;
}

static Node *
transformAExprOpAny(ParseState *pstate, A_Expr *a)
{
	Node	   *lexpr = transformExprRecurse(pstate, a->lexpr);
	Node	   *rexpr = transformExprRecurse(pstate, a->rexpr);

	return (Node *) make_scalar_array_op(pstate,
										 a->name,
										 true,
										 lexpr,
										 rexpr,
										 a->location);
}

static Node *
transformAExprOpAll(ParseState *pstate, A_Expr *a)
{
	Node	   *lexpr = transformExprRecurse(pstate, a->lexpr);
	Node	   *rexpr = transformExprRecurse(pstate, a->rexpr);

	return (Node *) make_scalar_array_op(pstate,
										 a->name,
										 false,
										 lexpr,
										 rexpr,
										 a->location);
}

static Node *
transformAExprDistinct(ParseState *pstate, A_Expr *a)
{
	Node	   *lexpr = a->lexpr;
	Node	   *rexpr = a->rexpr;
	Node	   *result;

	/*
	 * If either input is an undecorated NULL literal, transform to a NullTest
	 * on the other input. That's simpler to process than a full DistinctExpr,
	 * and it avoids needing to require that the datatype have an = operator.
	 */
	if (exprIsNullConstant(rexpr))
		return make_nulltest_from_distinct(pstate, a, lexpr);
	if (exprIsNullConstant(lexpr))
		return make_nulltest_from_distinct(pstate, a, rexpr);

	lexpr = transformExprRecurse(pstate, lexpr);
	rexpr = transformExprRecurse(pstate, rexpr);

	if (lexpr && IsA(lexpr, RowExpr) &&
		rexpr && IsA(rexpr, RowExpr))
	{
		/* ROW() op ROW() is handled specially */
		result = make_row_distinct_op(pstate, a->name,
									  (RowExpr *) lexpr,
									  (RowExpr *) rexpr,
									  a->location);
	}
	else
	{
		/* Ordinary scalar operator */
		result = (Node *) make_distinct_op(pstate,
										   a->name,
										   lexpr,
										   rexpr,
										   a->location);
	}

	/*
	 * If it's NOT DISTINCT, we first build a DistinctExpr and then stick a
	 * NOT on top.
	 */
	if (a->kind == AEXPR_NOT_DISTINCT)
		result = (Node *) makeBoolExpr(NOT_EXPR,
									   list_make1(result),
									   a->location);

	return result;
}

static Node *
transformAExprNullIf(ParseState *pstate, A_Expr *a)
{
	Node	   *lexpr = transformExprRecurse(pstate, a->lexpr);
	Node	   *rexpr = transformExprRecurse(pstate, a->rexpr);
	OpExpr	   *result;

	result = (OpExpr *) make_op(pstate,
								a->name,
								lexpr,
								rexpr,
								pstate->p_last_srf,
								a->location);

	/*
	 * The comparison operator itself should yield boolean ...
	 */
	if (result->opresulttype != BOOLOID)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
		/* translator: %s is name of a SQL construct, eg NULLIF */
				 errmsg("%s requires = operator to yield boolean", "NULLIF"),
				 parser_errposition(pstate, a->location)));
	if (result->opretset)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
		/* translator: %s is name of a SQL construct, eg NULLIF */
				 errmsg("%s must not return a set", "NULLIF"),
				 parser_errposition(pstate, a->location)));

	/*
	 * ... but the NullIfExpr will yield the first operand's type.
	 */
	result->opresulttype = exprType((Node *) linitial(result->args));

	/*
	 * We rely on NullIfExpr and OpExpr being the same struct
	 */
	NodeSetTag(result, T_NullIfExpr);

	return (Node *) result;
}

static Node *
transformAExprIn(ParseState *pstate, A_Expr *a)
{
	Node	   *result = NULL;
	Node	   *lexpr;
	List	   *rexprs;
	List	   *rvars;
	List	   *rnonvars;
	bool		useOr;
	ListCell   *l;
	bool		has_rvars = false;

	/*
	 * If the operator is <>, combine with AND not OR.
	 */
	if (strcmp(strVal(linitial(a->name)), "<>") == 0)
		useOr = false;
	else
		useOr = true;

	/*
	 * We try to generate a ScalarArrayOpExpr from IN/NOT IN, but this is only
	 * possible if there is a suitable array type available.  If not, we fall
	 * back to a boolean condition tree with multiple copies of the lefthand
	 * expression.  Also, any IN-list items that contain Vars are handled as
	 * separate boolean conditions, because that gives the planner more scope
	 * for optimization on such clauses.
	 *
	 * First step: transform all the inputs, and detect whether any contain
	 * Vars.
	 */
	lexpr = transformExprRecurse(pstate, a->lexpr);
	rexprs = rvars = rnonvars = NIL;
	foreach(l, (List *) a->rexpr)
	{
		Node	   *rexpr = transformExprRecurse(pstate, lfirst(l));

		rexprs = lappend(rexprs, rexpr);
		if (contain_vars_of_level(rexpr, 0))
		{
			rvars = lappend(rvars, rexpr);
			has_rvars = true;
		}
		else
			rnonvars = lappend(rnonvars, rexpr);
	}

	/*
	 * ScalarArrayOpExpr is only going to be useful if there's more than one
	 * non-Var righthand item.
	 */
	if (list_length(rnonvars) > 1)
	{
		List	   *allexprs;
		Oid			scalar_type;
		Oid			array_type;

		/*
		 * Try to select a common type for the array elements.  Note that
		 * since the LHS' type is first in the list, it will be preferred when
		 * there is doubt (eg, when all the RHS items are unknown literals).
		 *
		 * Note: use list_concat here not lcons, to avoid damaging rnonvars.
		 */
		allexprs = list_concat(list_make1(lexpr), rnonvars);
		scalar_type = select_common_type(pstate, allexprs, NULL, NULL);

		/* We have to verify that the selected type actually works */
		if (OidIsValid(scalar_type) &&
			!verify_common_type(scalar_type, allexprs))
			scalar_type = InvalidOid;

		/*
		 * Do we have an array type to use?  Aside from the case where there
		 * isn't one, we don't risk using ScalarArrayOpExpr when the common
		 * type is RECORD, because the RowExpr comparison logic below can cope
		 * with some cases of non-identical row types.
		 */
		if (OidIsValid(scalar_type) && scalar_type != RECORDOID)
			array_type = get_array_type(scalar_type);
		else
			array_type = InvalidOid;
		if (array_type != InvalidOid)
		{
			/*
			 * OK: coerce all the right-hand non-Var inputs to the common type
			 * and build an ArrayExpr for them.
			 */
			List	   *aexprs;
			ArrayExpr  *newa;

			aexprs = NIL;
			foreach(l, rnonvars)
			{
				Node	   *rexpr = (Node *) lfirst(l);

				rexpr = coerce_to_common_type(pstate, rexpr,
											  scalar_type,
											  "IN");
				aexprs = lappend(aexprs, rexpr);
			}
			newa = makeNode(ArrayExpr);
			newa->array_typeid = array_type;
			/* array_collid will be set by parse_collate.c */
			newa->element_typeid = scalar_type;
			newa->elements = aexprs;
			newa->multidims = false;
			newa->location = -1;

			/*
			 * If the IN expression contains Vars, disable query jumbling
			 * squashing.  Vars cannot be safely jumbled.
			 */
			newa->list_start = has_rvars ? -1 : a->rexpr_list_start;
			newa->list_end = has_rvars ? -1 : a->rexpr_list_end;

			result = (Node *) make_scalar_array_op(pstate,
												   a->name,
												   useOr,
												   lexpr,
												   (Node *) newa,
												   a->location);

			/* Consider only the Vars (if any) in the loop below */
			rexprs = rvars;
		}
	}

	/*
	 * Must do it the hard way, ie, with a boolean expression tree.
	 */
	foreach(l, rexprs)
	{
		Node	   *rexpr = (Node *) lfirst(l);
		Node	   *cmp;

		if (IsA(lexpr, RowExpr) &&
			IsA(rexpr, RowExpr))
		{
			/* ROW() op ROW() is handled specially */
			cmp = make_row_comparison_op(pstate,
										 a->name,
										 copyObject(((RowExpr *) lexpr)->args),
										 ((RowExpr *) rexpr)->args,
										 a->location);
		}
		else
		{
			/* Ordinary scalar operator */
			cmp = (Node *) make_op(pstate,
								   a->name,
								   copyObject(lexpr),
								   rexpr,
								   pstate->p_last_srf,
								   a->location);
		}

		cmp = coerce_to_boolean(pstate, cmp, "IN");
		if (result == NULL)
			result = cmp;
		else
			result = (Node *) makeBoolExpr(useOr ? OR_EXPR : AND_EXPR,
										   list_make2(result, cmp),
										   a->location);
	}

	return result;
}

static Node *
transformAExprBetween(ParseState *pstate, A_Expr *a)
{
	Node	   *aexpr;
	Node	   *bexpr;
	Node	   *cexpr;
	Node	   *result;
	Node	   *sub1;
	Node	   *sub2;
	List	   *args;

	/* Deconstruct A_Expr into three subexprs */
	aexpr = a->lexpr;
	args = castNode(List, a->rexpr);
	Assert(list_length(args) == 2);
	bexpr = (Node *) linitial(args);
	cexpr = (Node *) lsecond(args);

	/*
	 * Build the equivalent comparison expression.  Make copies of
	 * multiply-referenced subexpressions for safety.  (XXX this is really
	 * wrong since it results in multiple runtime evaluations of what may be
	 * volatile expressions ...)
	 *
	 * Ideally we would not use hard-wired operators here but instead use
	 * opclasses.  However, mixed data types and other issues make this
	 * difficult:
	 * http://archives.postgresql.org/pgsql-hackers/2008-08/msg01142.php
	 */
	switch (a->kind)
	{
		case AEXPR_BETWEEN:
			args = list_make2(makeSimpleA_Expr(AEXPR_OP, ">=",
											   aexpr, bexpr,
											   a->location),
							  makeSimpleA_Expr(AEXPR_OP, "<=",
											   copyObject(aexpr), cexpr,
											   a->location));
			result = (Node *) makeBoolExpr(AND_EXPR, args, a->location);
			break;
		case AEXPR_NOT_BETWEEN:
			args = list_make2(makeSimpleA_Expr(AEXPR_OP, "<",
											   aexpr, bexpr,
											   a->location),
							  makeSimpleA_Expr(AEXPR_OP, ">",
											   copyObject(aexpr), cexpr,
											   a->location));
			result = (Node *) makeBoolExpr(OR_EXPR, args, a->location);
			break;
		case AEXPR_BETWEEN_SYM:
			args = list_make2(makeSimpleA_Expr(AEXPR_OP, ">=",
											   aexpr, bexpr,
											   a->location),
							  makeSimpleA_Expr(AEXPR_OP, "<=",
											   copyObject(aexpr), cexpr,
											   a->location));
			sub1 = (Node *) makeBoolExpr(AND_EXPR, args, a->location);
			args = list_make2(makeSimpleA_Expr(AEXPR_OP, ">=",
											   copyObject(aexpr), copyObject(cexpr),
											   a->location),
							  makeSimpleA_Expr(AEXPR_OP, "<=",
											   copyObject(aexpr), copyObject(bexpr),
											   a->location));
			sub2 = (Node *) makeBoolExpr(AND_EXPR, args, a->location);
			args = list_make2(sub1, sub2);
			result = (Node *) makeBoolExpr(OR_EXPR, args, a->location);
			break;
		case AEXPR_NOT_BETWEEN_SYM:
			args = list_make2(makeSimpleA_Expr(AEXPR_OP, "<",
											   aexpr, bexpr,
											   a->location),
							  makeSimpleA_Expr(AEXPR_OP, ">",
											   copyObject(aexpr), cexpr,
											   a->location));
			sub1 = (Node *) makeBoolExpr(OR_EXPR, args, a->location);
			args = list_make2(makeSimpleA_Expr(AEXPR_OP, "<",
											   copyObject(aexpr), copyObject(cexpr),
											   a->location),
							  makeSimpleA_Expr(AEXPR_OP, ">",
											   copyObject(aexpr), copyObject(bexpr),
											   a->location));
			sub2 = (Node *) makeBoolExpr(OR_EXPR, args, a->location);
			args = list_make2(sub1, sub2);
			result = (Node *) makeBoolExpr(AND_EXPR, args, a->location);
			break;
		default:
			elog(ERROR, "unrecognized A_Expr kind: %d", a->kind);
			result = NULL;		/* keep compiler quiet */
			break;
	}

	return transformExprRecurse(pstate, result);
}

static Node *
transformMergeSupportFunc(ParseState *pstate, MergeSupportFunc *f)
{
	/*
	 * All we need to do is check that we're in the RETURNING list of a MERGE
	 * command.  If so, we just return the node as-is.
	 */
	if (pstate->p_expr_kind != EXPR_KIND_MERGE_RETURNING)
	{
		ParseState *parent_pstate = pstate->parentParseState;

		while (parent_pstate &&
			   parent_pstate->p_expr_kind != EXPR_KIND_MERGE_RETURNING)
			parent_pstate = parent_pstate->parentParseState;

		if (!parent_pstate)
			ereport(ERROR,
					errcode(ERRCODE_SYNTAX_ERROR),
					errmsg("MERGE_ACTION() can only be used in the RETURNING list of a MERGE command"),
					parser_errposition(pstate, f->location));
	}

	return (Node *) f;
}

static Node *
transformBoolExpr(ParseState *pstate, BoolExpr *a)
{
	List	   *args = NIL;
	const char *opname;
	ListCell   *lc;

	switch (a->boolop)
	{
		case AND_EXPR:
			opname = "AND";
			break;
		case OR_EXPR:
			opname = "OR";
			break;
		case NOT_EXPR:
			opname = "NOT";
			break;
		default:
			elog(ERROR, "unrecognized boolop: %d", (int) a->boolop);
			opname = NULL;		/* keep compiler quiet */
			break;
	}

	foreach(lc, a->args)
	{
		Node	   *arg = (Node *) lfirst(lc);

		arg = transformExprRecurse(pstate, arg);
		arg = coerce_to_boolean(pstate, arg, opname);
		args = lappend(args, arg);
	}

	return (Node *) makeBoolExpr(a->boolop, args, a->location);
}

static Node *
transformFuncCall(ParseState *pstate, FuncCall *fn)
{
	Node	   *last_srf = pstate->p_last_srf;
	List	   *targs;
	ListCell   *args;

	/* Transform the list of arguments ... */
	targs = NIL;
	foreach(args, fn->args)
	{
		targs = lappend(targs, transformExprRecurse(pstate,
													(Node *) lfirst(args)));
	}

	/*
	 * When WITHIN GROUP is used, we treat its ORDER BY expressions as
	 * additional arguments to the function, for purposes of function lookup
	 * and argument type coercion.  So, transform each such expression and add
	 * them to the targs list.  We don't explicitly mark where each argument
	 * came from, but ParseFuncOrColumn can tell what's what by reference to
	 * list_length(fn->agg_order).
	 */
	if (fn->agg_within_group)
	{
		Assert(fn->agg_order != NIL);
		foreach(args, fn->agg_order)
		{
			SortBy	   *arg = (SortBy *) lfirst(args);

			targs = lappend(targs, transformExpr(pstate, arg->node,
												 EXPR_KIND_ORDER_BY));
		}
	}

	/* ... and hand off to ParseFuncOrColumn */
	return ParseFuncOrColumn(pstate,
							 fn->funcname,
							 targs,
							 last_srf,
							 fn,
							 false,
							 fn->location);
}

static Node *
transformMultiAssignRef(ParseState *pstate, MultiAssignRef *maref)
{
	SubLink    *sublink;
	RowExpr    *rexpr;
	Query	   *qtree;
	TargetEntry *tle;

	/* We should only see this in first-stage processing of UPDATE tlists */
	Assert(pstate->p_expr_kind == EXPR_KIND_UPDATE_SOURCE);

	/* We only need to transform the source if this is the first column */
	if (maref->colno == 1)
	{
		/*
		 * For now, we only allow EXPR SubLinks and RowExprs as the source of
		 * an UPDATE multiassignment.  This is sufficient to cover interesting
		 * cases; at worst, someone would have to write (SELECT * FROM expr)
		 * to expand a composite-returning expression of another form.
		 */
		if (IsA(maref->source, SubLink) &&
			((SubLink *) maref->source)->subLinkType == EXPR_SUBLINK)
		{
			/* Relabel it as a MULTIEXPR_SUBLINK */
			sublink = (SubLink *) maref->source;
			sublink->subLinkType = MULTIEXPR_SUBLINK;
			/* And transform it */
			sublink = (SubLink *) transformExprRecurse(pstate,
													   (Node *) sublink);

			qtree = castNode(Query, sublink->subselect);

			/* Check subquery returns required number of columns */
			if (count_nonjunk_tlist_entries(qtree->targetList) != maref->ncolumns)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("number of columns does not match number of values"),
						 parser_errposition(pstate, sublink->location)));

			/*
			 * Build a resjunk tlist item containing the MULTIEXPR SubLink,
			 * and add it to pstate->p_multiassign_exprs, whence it will later
			 * get appended to the completed targetlist.  We needn't worry
			 * about selecting a resno for it; transformUpdateStmt will do
			 * that.
			 */
			tle = makeTargetEntry((Expr *) sublink, 0, NULL, true);
			pstate->p_multiassign_exprs = lappend(pstate->p_multiassign_exprs,
												  tle);

			/*
			 * Assign a unique-within-this-targetlist ID to the MULTIEXPR
			 * SubLink.  We can just use its position in the
			 * p_multiassign_exprs list.
			 */
			sublink->subLinkId = list_length(pstate->p_multiassign_exprs);
		}
		else if (IsA(maref->source, RowExpr))
		{
			/* Transform the RowExpr, allowing SetToDefault items */
			rexpr = (RowExpr *) transformRowExpr(pstate,
												 (RowExpr *) maref->source,
												 true);

			/* Check it returns required number of columns */
			if (list_length(rexpr->args) != maref->ncolumns)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("number of columns does not match number of values"),
						 parser_errposition(pstate, rexpr->location)));

			/*
			 * Temporarily append it to p_multiassign_exprs, so we can get it
			 * back when we come back here for additional columns.
			 */
			tle = makeTargetEntry((Expr *) rexpr, 0, NULL, true);
			pstate->p_multiassign_exprs = lappend(pstate->p_multiassign_exprs,
												  tle);
		}
		else
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("source for a multiple-column UPDATE item must be a sub-SELECT or ROW() expression"),
					 parser_errposition(pstate, exprLocation(maref->source))));
	}
	else
	{
		/*
		 * Second or later column in a multiassignment.  Re-fetch the
		 * transformed SubLink or RowExpr, which we assume is still the last
		 * entry in p_multiassign_exprs.
		 */
		Assert(pstate->p_multiassign_exprs != NIL);
		tle = (TargetEntry *) llast(pstate->p_multiassign_exprs);
	}

	/*
	 * Emit the appropriate output expression for the current column
	 */
	if (IsA(tle->expr, SubLink))
	{
		Param	   *param;

		sublink = (SubLink *) tle->expr;
		Assert(sublink->subLinkType == MULTIEXPR_SUBLINK);
		qtree = castNode(Query, sublink->subselect);

		/* Build a Param representing the current subquery output column */
		tle = (TargetEntry *) list_nth(qtree->targetList, maref->colno - 1);
		Assert(!tle->resjunk);

		param = makeNode(Param);
		param->paramkind = PARAM_MULTIEXPR;
		param->paramid = (sublink->subLinkId << 16) | maref->colno;
		param->paramtype = exprType((Node *) tle->expr);
		param->paramtypmod = exprTypmod((Node *) tle->expr);
		param->paramcollid = exprCollation((Node *) tle->expr);
		param->location = exprLocation((Node *) tle->expr);

		return (Node *) param;
	}

	if (IsA(tle->expr, RowExpr))
	{
		Node	   *result;

		rexpr = (RowExpr *) tle->expr;

		/* Just extract and return the next element of the RowExpr */
		result = (Node *) list_nth(rexpr->args, maref->colno - 1);

		/*
		 * If we're at the last column, delete the RowExpr from
		 * p_multiassign_exprs; we don't need it anymore, and don't want it in
		 * the finished UPDATE tlist.  We assume this is still the last entry
		 * in p_multiassign_exprs.
		 */
		if (maref->colno == maref->ncolumns)
			pstate->p_multiassign_exprs =
				list_delete_last(pstate->p_multiassign_exprs);

		return result;
	}

	elog(ERROR, "unexpected expr type in multiassign list");
	return NULL;				/* keep compiler quiet */
}

static Node *
transformCaseExpr(ParseState *pstate, CaseExpr *c)
{
	CaseExpr   *newc = makeNode(CaseExpr);
	Node	   *last_srf = pstate->p_last_srf;
	Node	   *arg;
	CaseTestExpr *placeholder;
	List	   *newargs;
	List	   *resultexprs;
	ListCell   *l;
	Node	   *defresult;
	Oid			ptype;

	/* transform the test expression, if any */
	arg = transformExprRecurse(pstate, (Node *) c->arg);

	/* generate placeholder for test expression */
	if (arg)
	{
		/*
		 * If test expression is an untyped literal, force it to text. We have
		 * to do something now because we won't be able to do this coercion on
		 * the placeholder.  This is not as flexible as what was done in 7.4
		 * and before, but it's good enough to handle the sort of silly coding
		 * commonly seen.
		 */
		if (exprType(arg) == UNKNOWNOID)
			arg = coerce_to_common_type(pstate, arg, TEXTOID, "CASE");

		/*
		 * Run collation assignment on the test expression so that we know
		 * what collation to mark the placeholder with.  In principle we could
		 * leave it to parse_collate.c to do that later, but propagating the
		 * result to the CaseTestExpr would be unnecessarily complicated.
		 */
		assign_expr_collations(pstate, arg);

		placeholder = makeNode(CaseTestExpr);
		placeholder->typeId = exprType(arg);
		placeholder->typeMod = exprTypmod(arg);
		placeholder->collation = exprCollation(arg);
	}
	else
		placeholder = NULL;

	newc->arg = (Expr *) arg;

	/* transform the list of arguments */
	newargs = NIL;
	resultexprs = NIL;
	foreach(l, c->args)
	{
		CaseWhen   *w = lfirst_node(CaseWhen, l);
		CaseWhen   *neww = makeNode(CaseWhen);
		Node	   *warg;

		warg = (Node *) w->expr;
		if (placeholder)
		{
			/* shorthand form was specified, so expand... */
			warg = (Node *) makeSimpleA_Expr(AEXPR_OP, "=",
											 (Node *) placeholder,
											 warg,
											 w->location);
		}
		neww->expr = (Expr *) transformExprRecurse(pstate, warg);

		neww->expr = (Expr *) coerce_to_boolean(pstate,
												(Node *) neww->expr,
												"CASE/WHEN");

		warg = (Node *) w->result;
		neww->result = (Expr *) transformExprRecurse(pstate, warg);
		neww->location = w->location;

		newargs = lappend(newargs, neww);
		resultexprs = lappend(resultexprs, neww->result);
	}

	newc->args = newargs;

	/* transform the default clause */
	defresult = (Node *) c->defresult;
	if (defresult == NULL)
	{
		A_Const    *n = makeNode(A_Const);

		n->isnull = true;
		n->location = -1;
		defresult = (Node *) n;
	}
	newc->defresult = (Expr *) transformExprRecurse(pstate, defresult);

	/*
	 * Note: default result is considered the most significant type in
	 * determining preferred type. This is how the code worked before, but it
	 * seems a little bogus to me --- tgl
	 */
	resultexprs = lcons(newc->defresult, resultexprs);

	ptype = select_common_type(pstate, resultexprs, "CASE", NULL);
	Assert(OidIsValid(ptype));
	newc->casetype = ptype;
	/* casecollid will be set by parse_collate.c */

	/* Convert default result clause, if necessary */
	newc->defresult = (Expr *)
		coerce_to_common_type(pstate,
							  (Node *) newc->defresult,
							  ptype,
							  "CASE/ELSE");

	/* Convert when-clause results, if necessary */
	foreach(l, newc->args)
	{
		CaseWhen   *w = (CaseWhen *) lfirst(l);

		w->result = (Expr *)
			coerce_to_common_type(pstate,
								  (Node *) w->result,
								  ptype,
								  "CASE/WHEN");
	}

	/* if any subexpression contained a SRF, complain */
	if (pstate->p_last_srf != last_srf)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
		/* translator: %s is name of a SQL construct, eg GROUP BY */
				 errmsg("set-returning functions are not allowed in %s",
						"CASE"),
				 errhint("You might be able to move the set-returning function into a LATERAL FROM item."),
				 parser_errposition(pstate,
									exprLocation(pstate->p_last_srf))));

	newc->location = c->location;

	return (Node *) newc;
}

static Node *
transformSubLink(ParseState *pstate, SubLink *sublink)
{
	Node	   *result = (Node *) sublink;
	Query	   *qtree;
	const char *err;

	/*
	 * Check to see if the sublink is in an invalid place within the query. We
	 * allow sublinks everywhere in SELECT/INSERT/UPDATE/DELETE/MERGE, but
	 * generally not in utility statements.
	 */
	err = NULL;
	switch (pstate->p_expr_kind)
	{
		case EXPR_KIND_NONE:
			Assert(false);		/* can't happen */
			break;
		case EXPR_KIND_OTHER:
			/* Accept sublink here; caller must throw error if wanted */
			break;
		case EXPR_KIND_JOIN_ON:
		case EXPR_KIND_JOIN_USING:
		case EXPR_KIND_FROM_SUBSELECT:
		case EXPR_KIND_FROM_FUNCTION:
		case EXPR_KIND_WHERE:
		case EXPR_KIND_POLICY:
		case EXPR_KIND_HAVING:
		case EXPR_KIND_FILTER:
		case EXPR_KIND_WINDOW_PARTITION:
		case EXPR_KIND_WINDOW_ORDER:
		case EXPR_KIND_WINDOW_FRAME_RANGE:
		case EXPR_KIND_WINDOW_FRAME_ROWS:
		case EXPR_KIND_WINDOW_FRAME_GROUPS:
		case EXPR_KIND_SELECT_TARGET:
		case EXPR_KIND_INSERT_TARGET:
		case EXPR_KIND_UPDATE_SOURCE:
		case EXPR_KIND_UPDATE_TARGET:
		case EXPR_KIND_MERGE_WHEN:
		case EXPR_KIND_GROUP_BY:
		case EXPR_KIND_ORDER_BY:
		case EXPR_KIND_DISTINCT_ON:
		case EXPR_KIND_LIMIT:
		case EXPR_KIND_OFFSET:
		case EXPR_KIND_RETURNING:
		case EXPR_KIND_MERGE_RETURNING:
		case EXPR_KIND_VALUES:
		case EXPR_KIND_VALUES_SINGLE:
		case EXPR_KIND_CYCLE_MARK:
			/* okay */
			break;
		case EXPR_KIND_CHECK_CONSTRAINT:
		case EXPR_KIND_DOMAIN_CHECK:
			err = _("cannot use subquery in check constraint");
			break;
		case EXPR_KIND_COLUMN_DEFAULT:
		case EXPR_KIND_FUNCTION_DEFAULT:
			err = _("cannot use subquery in DEFAULT expression");
			break;
		case EXPR_KIND_INDEX_EXPRESSION:
			err = _("cannot use subquery in index expression");
			break;
		case EXPR_KIND_INDEX_PREDICATE:
			err = _("cannot use subquery in index predicate");
			break;
		case EXPR_KIND_STATS_EXPRESSION:
			err = _("cannot use subquery in statistics expression");
			break;
		case EXPR_KIND_ALTER_COL_TRANSFORM:
			err = _("cannot use subquery in transform expression");
			break;
		case EXPR_KIND_EXECUTE_PARAMETER:
			err = _("cannot use subquery in EXECUTE parameter");
			break;
		case EXPR_KIND_TRIGGER_WHEN:
			err = _("cannot use subquery in trigger WHEN condition");
			break;
		case EXPR_KIND_PARTITION_BOUND:
			err = _("cannot use subquery in partition bound");
			break;
		case EXPR_KIND_PARTITION_EXPRESSION:
			err = _("cannot use subquery in partition key expression");
			break;
		case EXPR_KIND_CALL_ARGUMENT:
			err = _("cannot use subquery in CALL argument");
			break;
		case EXPR_KIND_COPY_WHERE:
			err = _("cannot use subquery in COPY FROM WHERE condition");
			break;
		case EXPR_KIND_GENERATED_COLUMN:
			err = _("cannot use subquery in column generation expression");
			break;

			/*
			 * There is intentionally no default: case here, so that the
			 * compiler will warn if we add a new ParseExprKind without
			 * extending this switch.  If we do see an unrecognized value at
			 * runtime, the behavior will be the same as for EXPR_KIND_OTHER,
			 * which is sane anyway.
			 */
	}
	if (err)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg_internal("%s", err),
				 parser_errposition(pstate, sublink->location)));

	pstate->p_hasSubLinks = true;

	/*
	 * OK, let's transform the sub-SELECT.
	 */
	qtree = parse_sub_analyze(sublink->subselect, pstate, NULL, false, true);

	/*
	 * Check that we got a SELECT.  Anything else should be impossible given
	 * restrictions of the grammar, but check anyway.
	 */
	if (!IsA(qtree, Query) ||
		qtree->commandType != CMD_SELECT)
		elog(ERROR, "unexpected non-SELECT command in SubLink");

	sublink->subselect = (Node *) qtree;

	if (sublink->subLinkType == EXISTS_SUBLINK)
	{
		/*
		 * EXISTS needs no test expression or combining operator. These fields
		 * should be null already, but make sure.
		 */
		sublink->testexpr = NULL;
		sublink->operName = NIL;
	}
	else if (sublink->subLinkType == EXPR_SUBLINK ||
			 sublink->subLinkType == ARRAY_SUBLINK)
	{
		/*
		 * Make sure the subselect delivers a single column (ignoring resjunk
		 * targets).
		 */
		if (count_nonjunk_tlist_entries(qtree->targetList) != 1)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("subquery must return only one column"),
					 parser_errposition(pstate, sublink->location)));

		/*
		 * EXPR and ARRAY need no test expression or combining operator. These
		 * fields should be null already, but make sure.
		 */
		sublink->testexpr = NULL;
		sublink->operName = NIL;
	}
	else if (sublink->subLinkType == MULTIEXPR_SUBLINK)
	{
		/* Same as EXPR case, except no restriction on number of columns */
		sublink->testexpr = NULL;
		sublink->operName = NIL;
	}
	else
	{
		/* ALL, ANY, or ROWCOMPARE: generate row-comparing expression */
		Node	   *lefthand;
		List	   *left_list;
		List	   *right_list;
		ListCell   *l;

		/*
		 * If the source was "x IN (select)", convert to "x = ANY (select)".
		 */
		if (sublink->operName == NIL)
			sublink->operName = list_make1(makeString("="));

		/*
		 * Transform lefthand expression, and convert to a list
		 */
		lefthand = transformExprRecurse(pstate, sublink->testexpr);
		if (lefthand && IsA(lefthand, RowExpr))
			left_list = ((RowExpr *) lefthand)->args;
		else
			left_list = list_make1(lefthand);

		/*
		 * Build a list of PARAM_SUBLINK nodes representing the output columns
		 * of the subquery.
		 */
		right_list = NIL;
		foreach(l, qtree->targetList)
		{
			TargetEntry *tent = (TargetEntry *) lfirst(l);
			Param	   *param;

			if (tent->resjunk)
				continue;

			param = makeNode(Param);
			param->paramkind = PARAM_SUBLINK;
			param->paramid = tent->resno;
			param->paramtype = exprType((Node *) tent->expr);
			param->paramtypmod = exprTypmod((Node *) tent->expr);
			param->paramcollid = exprCollation((Node *) tent->expr);
			param->location = -1;

			right_list = lappend(right_list, param);
		}

		/*
		 * We could rely on make_row_comparison_op to complain if the list
		 * lengths differ, but we prefer to generate a more specific error
		 * message.
		 */
		if (list_length(left_list) < list_length(right_list))
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("subquery has too many columns"),
					 parser_errposition(pstate, sublink->location)));
		if (list_length(left_list) > list_length(right_list))
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("subquery has too few columns"),
					 parser_errposition(pstate, sublink->location)));

		/*
		 * Identify the combining operator(s) and generate a suitable
		 * row-comparison expression.
		 */
		sublink->testexpr = make_row_comparison_op(pstate,
												   sublink->operName,
												   left_list,
												   right_list,
												   sublink->location);
	}

	return result;
}

/*
 * transformArrayExpr
 *
 * If the caller specifies the target type, the resulting array will
 * be of exactly that type.  Otherwise we try to infer a common type
 * for the elements using select_common_type().
 */
static Node *
transformArrayExpr(ParseState *pstate, A_ArrayExpr *a,
				   Oid array_type, Oid element_type, int32 typmod)
{
	ArrayExpr  *newa = makeNode(ArrayExpr);
	List	   *newelems = NIL;
	List	   *newcoercedelems = NIL;
	ListCell   *element;
	Oid			coerce_type;
	bool		coerce_hard;

	/*
	 * Transform the element expressions
	 *
	 * Assume that the array is one-dimensional unless we find an array-type
	 * element expression.
	 */
	newa->multidims = false;
	foreach(element, a->elements)
	{
		Node	   *e = (Node *) lfirst(element);
		Node	   *newe;

		/*
		 * If an element is itself an A_ArrayExpr, recurse directly so that we
		 * can pass down any target type we were given.
		 */
		if (IsA(e, A_ArrayExpr))
		{
			newe = transformArrayExpr(pstate,
									  (A_ArrayExpr *) e,
									  array_type,
									  element_type,
									  typmod);
			/* we certainly have an array here */
			Assert(array_type == InvalidOid || array_type == exprType(newe));
			newa->multidims = true;
		}
		else
		{
			newe = transformExprRecurse(pstate, e);

			/*
			 * Check for sub-array expressions, if we haven't already found
			 * one.  Note we don't accept domain-over-array as a sub-array,
			 * nor int2vector nor oidvector; those have constraints that don't
			 * map well to being treated as a sub-array.
			 */
			if (!newa->multidims)
			{
				Oid			newetype = exprType(newe);

				if (newetype != INT2VECTOROID && newetype != OIDVECTOROID &&
					type_is_array(newetype))
					newa->multidims = true;
			}
		}

		newelems = lappend(newelems, newe);
	}

	/*
	 * Select a target type for the elements.
	 *
	 * If we haven't been given a target array type, we must try to deduce a
	 * common type based on the types of the individual elements present.
	 */
	if (OidIsValid(array_type))
	{
		/* Caller must ensure array_type matches element_type */
		Assert(OidIsValid(element_type));
		coerce_type = (newa->multidims ? array_type : element_type);
		coerce_hard = true;
	}
	else
	{
		/* Can't handle an empty array without a target type */
		if (newelems == NIL)
			ereport(ERROR,
					(errcode(ERRCODE_INDETERMINATE_DATATYPE),
					 errmsg("cannot determine type of empty array"),
					 errhint("Explicitly cast to the desired type, "
							 "for example ARRAY[]::integer[]."),
					 parser_errposition(pstate, a->location)));

		/* Select a common type for the elements */
		coerce_type = select_common_type(pstate, newelems, "ARRAY", NULL);

		if (newa->multidims)
		{
			array_type = coerce_type;
			element_type = get_element_type(array_type);
			if (!OidIsValid(element_type))
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_OBJECT),
						 errmsg("could not find element type for data type %s",
								format_type_be(array_type)),
						 parser_errposition(pstate, a->location)));
		}
		else
		{
			element_type = coerce_type;
			array_type = get_array_type(element_type);
			if (!OidIsValid(array_type))
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_OBJECT),
						 errmsg("could not find array type for data type %s",
								format_type_be(element_type)),
						 parser_errposition(pstate, a->location)));
		}
		coerce_hard = false;
	}

	/*
	 * Coerce elements to target type
	 *
	 * If the array has been explicitly cast, then the elements are in turn
	 * explicitly coerced.
	 *
	 * If the array's type was merely derived from the common type of its
	 * elements, then the elements are implicitly coerced to the common type.
	 * This is consistent with other uses of select_common_type().
	 */
	foreach(element, newelems)
	{
		Node	   *e = (Node *) lfirst(element);
		Node	   *newe;

		if (coerce_hard)
		{
			newe = coerce_to_target_type(pstate, e,
										 exprType(e),
										 coerce_type,
										 typmod,
										 COERCION_EXPLICIT,
										 COERCE_EXPLICIT_CAST,
										 -1);
			if (newe == NULL)
				ereport(ERROR,
						(errcode(ERRCODE_CANNOT_COERCE),
						 errmsg("cannot cast type %s to %s",
								format_type_be(exprType(e)),
								format_type_be(coerce_type)),
						 parser_errposition(pstate, exprLocation(e))));
		}
		else
			newe = coerce_to_common_type(pstate, e,
										 coerce_type,
										 "ARRAY");
		newcoercedelems = lappend(newcoercedelems, newe);
	}

	newa->array_typeid = array_type;
	/* array_collid will be set by parse_collate.c */
	newa->element_typeid = element_type;
	newa->elements = newcoercedelems;
	newa->list_start = a->list_start;
	newa->list_end = a->list_end;
	newa->location = a->location;

	return (Node *) newa;
}

static Node *
transformRowExpr(ParseState *pstate, RowExpr *r, bool allowDefault)
{
	RowExpr    *newr;
	char		fname[16];
	int			fnum;

	newr = makeNode(RowExpr);

	/* Transform the field expressions */
	newr->args = transformExpressionList(pstate, r->args,
										 pstate->p_expr_kind, allowDefault);

	/* Disallow more columns than will fit in a tuple */
	if (list_length(newr->args) > MaxTupleAttributeNumber)
		ereport(ERROR,
				(errcode(ERRCODE_TOO_MANY_COLUMNS),
				 errmsg("ROW expressions can have at most %d entries",
						MaxTupleAttributeNumber),
				 parser_errposition(pstate, r->location)));

	/* Barring later casting, we consider the type RECORD */
	newr->row_typeid = RECORDOID;
	newr->row_format = COERCE_IMPLICIT_CAST;

	/* ROW() has anonymous columns, so invent some field names */
	newr->colnames = NIL;
	for (fnum = 1; fnum <= list_length(newr->args); fnum++)
	{
		snprintf(fname, sizeof(fname), "f%d", fnum);
		newr->colnames = lappend(newr->colnames, makeString(pstrdup(fname)));
	}

	newr->location = r->location;

	return (Node *) newr;
}

static Node *
transformCoalesceExpr(ParseState *pstate, CoalesceExpr *c)
{
	CoalesceExpr *newc = makeNode(CoalesceExpr);
	Node	   *last_srf = pstate->p_last_srf;
	List	   *newargs = NIL;
	List	   *newcoercedargs = NIL;
	ListCell   *args;

	foreach(args, c->args)
	{
		Node	   *e = (Node *) lfirst(args);
		Node	   *newe;

		newe = transformExprRecurse(pstate, e);
		newargs = lappend(newargs, newe);
	}

	newc->coalescetype = select_common_type(pstate, newargs, "COALESCE", NULL);
	/* coalescecollid will be set by parse_collate.c */

	/* Convert arguments if necessary */
	foreach(args, newargs)
	{
		Node	   *e = (Node *) lfirst(args);
		Node	   *newe;

		newe = coerce_to_common_type(pstate, e,
									 newc->coalescetype,
									 "COALESCE");
		newcoercedargs = lappend(newcoercedargs, newe);
	}

	/* if any subexpression contained a SRF, complain */
	if (pstate->p_last_srf != last_srf)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
		/* translator: %s is name of a SQL construct, eg GROUP BY */
				 errmsg("set-returning functions are not allowed in %s",
						"COALESCE"),
				 errhint("You might be able to move the set-returning function into a LATERAL FROM item."),
				 parser_errposition(pstate,
									exprLocation(pstate->p_last_srf))));

	newc->args = newcoercedargs;
	newc->location = c->location;
	return (Node *) newc;
}

static Node *
transformMinMaxExpr(ParseState *pstate, MinMaxExpr *m)
{
	MinMaxExpr *newm = makeNode(MinMaxExpr);
	List	   *newargs = NIL;
	List	   *newcoercedargs = NIL;
	const char *funcname = (m->op == IS_GREATEST) ? "GREATEST" : "LEAST";
	ListCell   *args;

	newm->op = m->op;
	foreach(args, m->args)
	{
		Node	   *e = (Node *) lfirst(args);
		Node	   *newe;

		newe = transformExprRecurse(pstate, e);
		newargs = lappend(newargs, newe);
	}

	newm->minmaxtype = select_common_type(pstate, newargs, funcname, NULL);
	/* minmaxcollid and inputcollid will be set by parse_collate.c */

	/* Convert arguments if necessary */
	foreach(args, newargs)
	{
		Node	   *e = (Node *) lfirst(args);
		Node	   *newe;

		newe = coerce_to_common_type(pstate, e,
									 newm->minmaxtype,
									 funcname);
		newcoercedargs = lappend(newcoercedargs, newe);
	}

	newm->args = newcoercedargs;
	newm->location = m->location;
	return (Node *) newm;
}

static Node *
transformSQLValueFunction(ParseState *pstate, SQLValueFunction *svf)
{
	/*
	 * All we need to do is insert the correct result type and (where needed)
	 * validate the typmod, so we just modify the node in-place.
	 */
	switch (svf->op)
	{
		case SVFOP_CURRENT_DATE:
			svf->type = DATEOID;
			break;
		case SVFOP_CURRENT_TIME:
			svf->type = TIMETZOID;
			break;
		case SVFOP_CURRENT_TIME_N:
			svf->type = TIMETZOID;
			svf->typmod = anytime_typmod_check(true, svf->typmod);
			break;
		case SVFOP_CURRENT_TIMESTAMP:
			svf->type = TIMESTAMPTZOID;
			break;
		case SVFOP_CURRENT_TIMESTAMP_N:
			svf->type = TIMESTAMPTZOID;
			svf->typmod = anytimestamp_typmod_check(true, svf->typmod);
			break;
		case SVFOP_LOCALTIME:
			svf->type = TIMEOID;
			break;
		case SVFOP_LOCALTIME_N:
			svf->type = TIMEOID;
			svf->typmod = anytime_typmod_check(false, svf->typmod);
			break;
		case SVFOP_LOCALTIMESTAMP:
			svf->type = TIMESTAMPOID;
			break;
		case SVFOP_LOCALTIMESTAMP_N:
			svf->type = TIMESTAMPOID;
			svf->typmod = anytimestamp_typmod_check(false, svf->typmod);
			break;
		case SVFOP_CURRENT_ROLE:
		case SVFOP_CURRENT_USER:
		case SVFOP_USER:
		case SVFOP_SESSION_USER:
		case SVFOP_CURRENT_CATALOG:
		case SVFOP_CURRENT_SCHEMA:
			svf->type = NAMEOID;
			break;
	}

	return (Node *) svf;
}

static Node *
transformXmlExpr(ParseState *pstate, XmlExpr *x)
{
	XmlExpr    *newx;
	ListCell   *lc;
	int			i;

	newx = makeNode(XmlExpr);
	newx->op = x->op;
	if (x->name)
		newx->name = map_sql_identifier_to_xml_name(x->name, false, false);
	else
		newx->name = NULL;
	newx->xmloption = x->xmloption;
	newx->type = XMLOID;		/* this just marks the node as transformed */
	newx->typmod = -1;
	newx->location = x->location;

	/*
	 * gram.y built the named args as a list of ResTarget.  Transform each,
	 * and break the names out as a separate list.
	 */
	newx->named_args = NIL;
	newx->arg_names = NIL;

	foreach(lc, x->named_args)
	{
		ResTarget  *r = lfirst_node(ResTarget, lc);
		Node	   *expr;
		char	   *argname;

		expr = transformExprRecurse(pstate, r->val);

		if (r->name)
			argname = map_sql_identifier_to_xml_name(r->name, false, false);
		else if (IsA(r->val, ColumnRef))
			argname = map_sql_identifier_to_xml_name(FigureColname(r->val),
													 true, false);
		else
		{
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 x->op == IS_XMLELEMENT
					 ? errmsg("unnamed XML attribute value must be a column reference")
					 : errmsg("unnamed XML element value must be a column reference"),
					 parser_errposition(pstate, r->location)));
			argname = NULL;		/* keep compiler quiet */
		}

		/* reject duplicate argnames in XMLELEMENT only */
		if (x->op == IS_XMLELEMENT)
		{
			ListCell   *lc2;

			foreach(lc2, newx->arg_names)
			{
				if (strcmp(argname, strVal(lfirst(lc2))) == 0)
					ereport(ERROR,
							(errcode(ERRCODE_SYNTAX_ERROR),
							 errmsg("XML attribute name \"%s\" appears more than once",
									argname),
							 parser_errposition(pstate, r->location)));
			}
		}

		newx->named_args = lappend(newx->named_args, expr);
		newx->arg_names = lappend(newx->arg_names, makeString(argname));
	}

	/* The other arguments are of varying types depending on the function */
	newx->args = NIL;
	i = 0;
	foreach(lc, x->args)
	{
		Node	   *e = (Node *) lfirst(lc);
		Node	   *newe;

		newe = transformExprRecurse(pstate, e);
		switch (x->op)
		{
			case IS_XMLCONCAT:
				newe = coerce_to_specific_type(pstate, newe, XMLOID,
											   "XMLCONCAT");
				break;
			case IS_XMLELEMENT:
				/* no coercion necessary */
				break;
			case IS_XMLFOREST:
				newe = coerce_to_specific_type(pstate, newe, XMLOID,
											   "XMLFOREST");
				break;
			case IS_XMLPARSE:
				if (i == 0)
					newe = coerce_to_specific_type(pstate, newe, TEXTOID,
												   "XMLPARSE");
				else
					newe = coerce_to_boolean(pstate, newe, "XMLPARSE");
				break;
			case IS_XMLPI:
				newe = coerce_to_specific_type(pstate, newe, TEXTOID,
											   "XMLPI");
				break;
			case IS_XMLROOT:
				if (i == 0)
					newe = coerce_to_specific_type(pstate, newe, XMLOID,
												   "XMLROOT");
				else if (i == 1)
					newe = coerce_to_specific_type(pstate, newe, TEXTOID,
												   "XMLROOT");
				else
					newe = coerce_to_specific_type(pstate, newe, INT4OID,
												   "XMLROOT");
				break;
			case IS_XMLSERIALIZE:
				/* not handled here */
				Assert(false);
				break;
			case IS_DOCUMENT:
				newe = coerce_to_specific_type(pstate, newe, XMLOID,
											   "IS DOCUMENT");
				break;
		}
		newx->args = lappend(newx->args, newe);
		i++;
	}

	return (Node *) newx;
}

static Node *
transformXmlSerialize(ParseState *pstate, XmlSerialize *xs)
{
	Node	   *result;
	XmlExpr    *xexpr;
	Oid			targetType;
	int32		targetTypmod;

	xexpr = makeNode(XmlExpr);
	xexpr->op = IS_XMLSERIALIZE;
	xexpr->args = list_make1(coerce_to_specific_type(pstate,
													 transformExprRecurse(pstate, xs->expr),
													 XMLOID,
													 "XMLSERIALIZE"));

	typenameTypeIdAndMod(pstate, xs->typeName, &targetType, &targetTypmod);

	xexpr->xmloption = xs->xmloption;
	xexpr->indent = xs->indent;
	xexpr->location = xs->location;
	/* We actually only need these to be able to parse back the expression. */
	xexpr->type = targetType;
	xexpr->typmod = targetTypmod;

	/*
	 * The actual target type is determined this way.  SQL allows char and
	 * varchar as target types.  We allow anything that can be cast implicitly
	 * from text.  This way, user-defined text-like data types automatically
	 * fit in.
	 */
	result = coerce_to_target_type(pstate, (Node *) xexpr,
								   TEXTOID, targetType, targetTypmod,
								   COERCION_IMPLICIT,
								   COERCE_IMPLICIT_CAST,
								   -1);
	if (result == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_CANNOT_COERCE),
				 errmsg("cannot cast XMLSERIALIZE result to %s",
						format_type_be(targetType)),
				 parser_errposition(pstate, xexpr->location)));
	return result;
}

static Node *
transformBooleanTest(ParseState *pstate, BooleanTest *b)
{
	const char *clausename;

	switch (b->booltesttype)
	{
		case IS_TRUE:
			clausename = "IS TRUE";
			break;
		case IS_NOT_TRUE:
			clausename = "IS NOT TRUE";
			break;
		case IS_FALSE:
			clausename = "IS FALSE";
			break;
		case IS_NOT_FALSE:
			clausename = "IS NOT FALSE";
			break;
		case IS_UNKNOWN:
			clausename = "IS UNKNOWN";
			break;
		case IS_NOT_UNKNOWN:
			clausename = "IS NOT UNKNOWN";
			break;
		default:
			elog(ERROR, "unrecognized booltesttype: %d",
				 (int) b->booltesttype);
			clausename = NULL;	/* keep compiler quiet */
	}

	b->arg = (Expr *) transformExprRecurse(pstate, (Node *) b->arg);

	b->arg = (Expr *) coerce_to_boolean(pstate,
										(Node *) b->arg,
										clausename);

	return (Node *) b;
}

static Node *
transformCurrentOfExpr(ParseState *pstate, CurrentOfExpr *cexpr)
{
	/* CURRENT OF can only appear at top level of UPDATE/DELETE */
	Assert(pstate->p_target_nsitem != NULL);
	cexpr->cvarno = pstate->p_target_nsitem->p_rtindex;

	/*
	 * Check to see if the cursor name matches a parameter of type REFCURSOR.
	 * If so, replace the raw name reference with a parameter reference. (This
	 * is a hack for the convenience of plpgsql.)
	 */
	if (cexpr->cursor_name != NULL) /* in case already transformed */
	{
		ColumnRef  *cref = makeNode(ColumnRef);
		Node	   *node = NULL;

		/* Build an unqualified ColumnRef with the given name */
		cref->fields = list_make1(makeString(cexpr->cursor_name));
		cref->location = -1;

		/* See if there is a translation available from a parser hook */
		if (pstate->p_pre_columnref_hook != NULL)
			node = pstate->p_pre_columnref_hook(pstate, cref);
		if (node == NULL && pstate->p_post_columnref_hook != NULL)
			node = pstate->p_post_columnref_hook(pstate, cref, NULL);

		/*
		 * XXX Should we throw an error if we get a translation that isn't a
		 * refcursor Param?  For now it seems best to silently ignore false
		 * matches.
		 */
		if (node != NULL && IsA(node, Param))
		{
			Param	   *p = (Param *) node;

			if (p->paramkind == PARAM_EXTERN &&
				p->paramtype == REFCURSOROID)
			{
				/* Matches, so convert CURRENT OF to a param reference */
				cexpr->cursor_name = NULL;
				cexpr->cursor_param = p->paramid;
			}
		}
	}

	return (Node *) cexpr;
}

/*
 * Construct a whole-row reference to represent the notation "relation.*".
 */
static Node *
transformWholeRowRef(ParseState *pstate, ParseNamespaceItem *nsitem,
					 int sublevels_up, int location)
{
	/*
	 * Build the appropriate referencing node.  Normally this can be a
	 * whole-row Var, but if the nsitem is a JOIN USING alias then it contains
	 * only a subset of the columns of the underlying join RTE, so that will
	 * not work.  Instead we immediately expand the reference into a RowExpr.
	 * Since the JOIN USING's common columns are fully determined at this
	 * point, there seems no harm in expanding it now rather than during
	 * planning.
	 *
	 * Note that if the nsitem is an OLD/NEW alias for the target RTE (as can
	 * appear in a RETURNING list), its alias won't match the target RTE's
	 * alias, but we still want to make a whole-row Var here rather than a
	 * RowExpr, for consistency with direct references to the target RTE, and
	 * so that any dropped columns are handled correctly.  Thus we also check
	 * p_returning_type here.
	 *
	 * Note that if the RTE is a function returning scalar, we create just a
	 * plain reference to the function value, not a composite containing a
	 * single column.  This is pretty inconsistent at first sight, but it's
	 * what we've done historically.  One argument for it is that "rel" and
	 * "rel.*" mean the same thing for composite relations, so why not for
	 * scalar functions...
	 */
	if (nsitem->p_names == nsitem->p_rte->eref ||
		nsitem->p_returning_type != VAR_RETURNING_DEFAULT)
	{
		Var		   *result;

		result = makeWholeRowVar(nsitem->p_rte, nsitem->p_rtindex,
								 sublevels_up, true);

		/* mark Var for RETURNING OLD/NEW, as necessary */
		result->varreturningtype = nsitem->p_returning_type;

		/* location is not filled in by makeWholeRowVar */
		result->location = location;

		/* mark Var if it's nulled by any outer joins */
		markNullableIfNeeded(pstate, result);

		/* mark relation as requiring whole-row SELECT access */
		markVarForSelectPriv(pstate, result);

		return (Node *) result;
	}
	else
	{
		RowExpr    *rowexpr;
		List	   *fields;

		/*
		 * We want only as many columns as are listed in p_names->colnames,
		 * and we should use those names not whatever possibly-aliased names
		 * are in the RTE.  We needn't worry about marking the RTE for SELECT
		 * access, as the common columns are surely so marked already.
		 */
		expandRTE(nsitem->p_rte, nsitem->p_rtindex, sublevels_up,
				  nsitem->p_returning_type, location, false, NULL, &fields);
		rowexpr = makeNode(RowExpr);
		rowexpr->args = list_truncate(fields,
									  list_length(nsitem->p_names->colnames));
		rowexpr->row_typeid = RECORDOID;
		rowexpr->row_format = COERCE_IMPLICIT_CAST;
		rowexpr->colnames = copyObject(nsitem->p_names->colnames);
		rowexpr->location = location;

		/* XXX we ought to mark the row as possibly nullable */

		return (Node *) rowexpr;
	}
}

/*
 * Handle an explicit CAST construct.
 *
 * Transform the argument, look up the type name, and apply any necessary
 * coercion function(s).
 */
static Node *
transformTypeCast(ParseState *pstate, TypeCast *tc)
{
	Node	   *result;
	Node	   *arg = tc->arg;
	Node	   *expr;
	Oid			inputType;
	Oid			targetType;
	int32		targetTypmod;
	int			location;

	/* Look up the type name first */
	typenameTypeIdAndMod(pstate, tc->typeName, &targetType, &targetTypmod);

	/*
	 * If the subject of the typecast is an ARRAY[] construct and the target
	 * type is an array type, we invoke transformArrayExpr() directly so that
	 * we can pass down the type information.  This avoids some cases where
	 * transformArrayExpr() might not infer the correct type.  Otherwise, just
	 * transform the argument normally.
	 */
	if (IsA(arg, A_ArrayExpr))
	{
		Oid			targetBaseType;
		int32		targetBaseTypmod;
		Oid			elementType;

		/*
		 * If target is a domain over array, work with the base array type
		 * here.  Below, we'll cast the array type to the domain.  In the
		 * usual case that the target is not a domain, the remaining steps
		 * will be a no-op.
		 */
		targetBaseTypmod = targetTypmod;
		targetBaseType = getBaseTypeAndTypmod(targetType, &targetBaseTypmod);
		elementType = get_element_type(targetBaseType);
		if (OidIsValid(elementType))
		{
			expr = transformArrayExpr(pstate,
									  (A_ArrayExpr *) arg,
									  targetBaseType,
									  elementType,
									  targetBaseTypmod);
		}
		else
			expr = transformExprRecurse(pstate, arg);
	}
	else
		expr = transformExprRecurse(pstate, arg);

	inputType = exprType(expr);
	if (inputType == InvalidOid)
		return expr;			/* do nothing if NULL input */

	/*
	 * Location of the coercion is preferentially the location of the :: or
	 * CAST symbol, but if there is none then use the location of the type
	 * name (this can happen in TypeName 'string' syntax, for instance).
	 */
	location = tc->location;
	if (location < 0)
		location = tc->typeName->location;

	result = coerce_to_target_type(pstate, expr, inputType,
								   targetType, targetTypmod,
								   COERCION_EXPLICIT,
								   COERCE_EXPLICIT_CAST,
								   location);
	if (result == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_CANNOT_COERCE),
				 errmsg("cannot cast type %s to %s",
						format_type_be(inputType),
						format_type_be(targetType)),
				 parser_coercion_errposition(pstate, location, expr)));

	return result;
}

/*
 * Handle an explicit COLLATE clause.
 *
 * Transform the argument, and look up the collation name.
 */
static Node *
transformCollateClause(ParseState *pstate, CollateClause *c)
{
	CollateExpr *newc;
	Oid			argtype;

	newc = makeNode(CollateExpr);
	newc->arg = (Expr *) transformExprRecurse(pstate, c->arg);

	argtype = exprType((Node *) newc->arg);

	/*
	 * The unknown type is not collatable, but coerce_type() takes care of it
	 * separately, so we'll let it go here.
	 */
	if (!type_is_collatable(argtype) && argtype != UNKNOWNOID)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("collations are not supported by type %s",
						format_type_be(argtype)),
				 parser_errposition(pstate, c->location)));

	newc->collOid = LookupCollation(pstate, c->collname, c->location);
	newc->location = c->location;

	return (Node *) newc;
}

/*
 * Transform a "row compare-op row" construct
 *
 * The inputs are lists of already-transformed expressions.
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 *
 * The output may be a single OpExpr, an AND or OR combination of OpExprs,
 * or a RowCompareExpr.  In all cases it is guaranteed to return boolean.
 * The AND, OR, and RowCompareExpr cases further imply things about the
 * behavior of the operators (ie, they behave as =, <>, or < <= > >=).
 */
static Node *
make_row_comparison_op(ParseState *pstate, List *opname,
					   List *largs, List *rargs, int location)
{
	RowCompareExpr *rcexpr;
	CompareType cmptype;
	List	   *opexprs;
	List	   *opnos;
	List	   *opfamilies;
	ListCell   *l,
			   *r;
	List	  **opinfo_lists;
	Bitmapset  *cmptypes;
	int			nopers;
	int			i;

	nopers = list_length(largs);
	if (nopers != list_length(rargs))
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("unequal number of entries in row expressions"),
				 parser_errposition(pstate, location)));

	/*
	 * We can't compare zero-length rows because there is no principled basis
	 * for figuring out what the operator is.
	 */
	if (nopers == 0)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("cannot compare rows of zero length"),
				 parser_errposition(pstate, location)));

	/*
	 * Identify all the pairwise operators, using make_op so that behavior is
	 * the same as in the simple scalar case.
	 */
	opexprs = NIL;
	forboth(l, largs, r, rargs)
	{
		Node	   *larg = (Node *) lfirst(l);
		Node	   *rarg = (Node *) lfirst(r);
		OpExpr	   *cmp;

		cmp = castNode(OpExpr, make_op(pstate, opname, larg, rarg,
									   pstate->p_last_srf, location));

		/*
		 * We don't use coerce_to_boolean here because we insist on the
		 * operator yielding boolean directly, not via coercion.  If it
		 * doesn't yield bool it won't be in any index opfamilies...
		 */
		if (cmp->opresulttype != BOOLOID)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("row comparison operator must yield type boolean, "
							"not type %s",
							format_type_be(cmp->opresulttype)),
					 parser_errposition(pstate, location)));
		if (expression_returns_set((Node *) cmp))
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("row comparison operator must not return a set"),
					 parser_errposition(pstate, location)));
		opexprs = lappend(opexprs, cmp);
	}

	/*
	 * If rows are length 1, just return the single operator.  In this case we
	 * don't insist on identifying btree semantics for the operator (but we
	 * still require it to return boolean).
	 */
	if (nopers == 1)
		return (Node *) linitial(opexprs);

	/*
	 * Now we must determine which row comparison semantics (= <> < <= > >=)
	 * apply to this set of operators.  We look for opfamilies containing the
	 * operators, and see which interpretations (cmptypes) exist for each
	 * operator.
	 */
	opinfo_lists = (List **) palloc(nopers * sizeof(List *));
	cmptypes = NULL;
	i = 0;
	foreach(l, opexprs)
	{
		Oid			opno = ((OpExpr *) lfirst(l))->opno;
		Bitmapset  *this_cmptypes;
		ListCell   *j;

		opinfo_lists[i] = get_op_index_interpretation(opno);

		/*
		 * convert comparison types into a Bitmapset to make the intersection
		 * calculation easy.
		 */
		this_cmptypes = NULL;
		foreach(j, opinfo_lists[i])
		{
			OpIndexInterpretation *opinfo = lfirst(j);

			this_cmptypes = bms_add_member(this_cmptypes, opinfo->cmptype);
		}
		if (i == 0)
			cmptypes = this_cmptypes;
		else
			cmptypes = bms_int_members(cmptypes, this_cmptypes);
		i++;
	}

	/*
	 * If there are multiple common interpretations, we may use any one of
	 * them ... this coding arbitrarily picks the lowest comparison type
	 * number.
	 */
	i = bms_next_member(cmptypes, -1);
	if (i < 0)
	{
		/* No common interpretation, so fail */
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("could not determine interpretation of row comparison operator %s",
						strVal(llast(opname))),
				 errhint("Row comparison operators must be associated with btree operator families."),
				 parser_errposition(pstate, location)));
	}
	cmptype = (CompareType) i;

	/*
	 * For = and <> cases, we just combine the pairwise operators with AND or
	 * OR respectively.
	 */
	if (cmptype == COMPARE_EQ)
		return (Node *) makeBoolExpr(AND_EXPR, opexprs, location);
	if (cmptype == COMPARE_NE)
		return (Node *) makeBoolExpr(OR_EXPR, opexprs, location);

	/*
	 * Otherwise we need to choose exactly which opfamily to associate with
	 * each operator.
	 */
	opfamilies = NIL;
	for (i = 0; i < nopers; i++)
	{
		Oid			opfamily = InvalidOid;
		ListCell   *j;

		foreach(j, opinfo_lists[i])
		{
			OpIndexInterpretation *opinfo = lfirst(j);

			if (opinfo->cmptype == cmptype)
			{
				opfamily = opinfo->opfamily_id;
				break;
			}
		}
		if (OidIsValid(opfamily))
			opfamilies = lappend_oid(opfamilies, opfamily);
		else					/* should not happen */
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("could not determine interpretation of row comparison operator %s",
							strVal(llast(opname))),
					 errdetail("There are multiple equally-plausible candidates."),
					 parser_errposition(pstate, location)));
	}

	/*
	 * Now deconstruct the OpExprs and create a RowCompareExpr.
	 *
	 * Note: can't just reuse the passed largs/rargs lists, because of
	 * possibility that make_op inserted coercion operations.
	 */
	opnos = NIL;
	largs = NIL;
	rargs = NIL;
	foreach(l, opexprs)
	{
		OpExpr	   *cmp = (OpExpr *) lfirst(l);

		opnos = lappend_oid(opnos, cmp->opno);
		largs = lappend(largs, linitial(cmp->args));
		rargs = lappend(rargs, lsecond(cmp->args));
	}

	rcexpr = makeNode(RowCompareExpr);
	rcexpr->cmptype = cmptype;
	rcexpr->opnos = opnos;
	rcexpr->opfamilies = opfamilies;
	rcexpr->inputcollids = NIL; /* assign_expr_collations will fix this */
	rcexpr->largs = largs;
	rcexpr->rargs = rargs;

	return (Node *) rcexpr;
}

/*
 * Transform a "row IS DISTINCT FROM row" construct
 *
 * The input RowExprs are already transformed
 */
static Node *
make_row_distinct_op(ParseState *pstate, List *opname,
					 RowExpr *lrow, RowExpr *rrow,
					 int location)
{
	Node	   *result = NULL;
	List	   *largs = lrow->args;
	List	   *rargs = rrow->args;
	ListCell   *l,
			   *r;

	if (list_length(largs) != list_length(rargs))
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("unequal number of entries in row expressions"),
				 parser_errposition(pstate, location)));

	forboth(l, largs, r, rargs)
	{
		Node	   *larg = (Node *) lfirst(l);
		Node	   *rarg = (Node *) lfirst(r);
		Node	   *cmp;

		cmp = (Node *) make_distinct_op(pstate, opname, larg, rarg, location);
		if (result == NULL)
			result = cmp;
		else
			result = (Node *) makeBoolExpr(OR_EXPR,
										   list_make2(result, cmp),
										   location);
	}

	if (result == NULL)
	{
		/* zero-length rows?  Generate constant FALSE */
		result = makeBoolConst(false, false);
	}

	return result;
}

/*
 * make the node for an IS DISTINCT FROM operator
 */
static Expr *
make_distinct_op(ParseState *pstate, List *opname, Node *ltree, Node *rtree,
				 int location)
{
	Expr	   *result;

	result = make_op(pstate, opname, ltree, rtree,
					 pstate->p_last_srf, location);
	if (((OpExpr *) result)->opresulttype != BOOLOID)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
		/* translator: %s is name of a SQL construct, eg NULLIF */
				 errmsg("%s requires = operator to yield boolean",
						"IS DISTINCT FROM"),
				 parser_errposition(pstate, location)));
	if (((OpExpr *) result)->opretset)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
		/* translator: %s is name of a SQL construct, eg NULLIF */
				 errmsg("%s must not return a set", "IS DISTINCT FROM"),
				 parser_errposition(pstate, location)));

	/*
	 * We rely on DistinctExpr and OpExpr being same struct
	 */
	NodeSetTag(result, T_DistinctExpr);

	return result;
}

/*
 * Produce a NullTest node from an IS [NOT] DISTINCT FROM NULL construct
 *
 * "arg" is the untransformed other argument
 */
static Node *
make_nulltest_from_distinct(ParseState *pstate, A_Expr *distincta, Node *arg)
{
	NullTest   *nt = makeNode(NullTest);

	nt->arg = (Expr *) transformExprRecurse(pstate, arg);
	/* the argument can be any type, so don't coerce it */
	if (distincta->kind == AEXPR_NOT_DISTINCT)
		nt->nulltesttype = IS_NULL;
	else
		nt->nulltesttype = IS_NOT_NULL;
	/* argisrow = false is correct whether or not arg is composite */
	nt->argisrow = false;
	nt->location = distincta->location;
	return (Node *) nt;
}

/*
 * Produce a string identifying an expression by kind.
 *
 * Note: when practical, use a simple SQL keyword for the result.  If that
 * doesn't work well, check call sites to see whether custom error message
 * strings are required.
 */
const char *
ParseExprKindName(ParseExprKind exprKind)
{
	switch (exprKind)
	{
		case EXPR_KIND_NONE:
			return "invalid expression context";
		case EXPR_KIND_OTHER:
			return "extension expression";
		case EXPR_KIND_JOIN_ON:
			return "JOIN/ON";
		case EXPR_KIND_JOIN_USING:
			return "JOIN/USING";
		case EXPR_KIND_FROM_SUBSELECT:
			return "sub-SELECT in FROM";
		case EXPR_KIND_FROM_FUNCTION:
			return "function in FROM";
		case EXPR_KIND_WHERE:
			return "WHERE";
		case EXPR_KIND_POLICY:
			return "POLICY";
		case EXPR_KIND_HAVING:
			return "HAVING";
		case EXPR_KIND_FILTER:
			return "FILTER";
		case EXPR_KIND_WINDOW_PARTITION:
			return "window PARTITION BY";
		case EXPR_KIND_WINDOW_ORDER:
			return "window ORDER BY";
		case EXPR_KIND_WINDOW_FRAME_RANGE:
			return "window RANGE";
		case EXPR_KIND_WINDOW_FRAME_ROWS:
			return "window ROWS";
		case EXPR_KIND_WINDOW_FRAME_GROUPS:
			return "window GROUPS";
		case EXPR_KIND_SELECT_TARGET:
			return "SELECT";
		case EXPR_KIND_INSERT_TARGET:
			return "INSERT";
		case EXPR_KIND_UPDATE_SOURCE:
		case EXPR_KIND_UPDATE_TARGET:
			return "UPDATE";
		case EXPR_KIND_MERGE_WHEN:
			return "MERGE WHEN";
		case EXPR_KIND_GROUP_BY:
			return "GROUP BY";
		case EXPR_KIND_ORDER_BY:
			return "ORDER BY";
		case EXPR_KIND_DISTINCT_ON:
			return "DISTINCT ON";
		case EXPR_KIND_LIMIT:
			return "LIMIT";
		case EXPR_KIND_OFFSET:
			return "OFFSET";
		case EXPR_KIND_RETURNING:
		case EXPR_KIND_MERGE_RETURNING:
			return "RETURNING";
		case EXPR_KIND_VALUES:
		case EXPR_KIND_VALUES_SINGLE:
			return "VALUES";
		case EXPR_KIND_CHECK_CONSTRAINT:
		case EXPR_KIND_DOMAIN_CHECK:
			return "CHECK";
		case EXPR_KIND_COLUMN_DEFAULT:
		case EXPR_KIND_FUNCTION_DEFAULT:
			return "DEFAULT";
		case EXPR_KIND_INDEX_EXPRESSION:
			return "index expression";
		case EXPR_KIND_INDEX_PREDICATE:
			return "index predicate";
		case EXPR_KIND_STATS_EXPRESSION:
			return "statistics expression";
		case EXPR_KIND_ALTER_COL_TRANSFORM:
			return "USING";
		case EXPR_KIND_EXECUTE_PARAMETER:
			return "EXECUTE";
		case EXPR_KIND_TRIGGER_WHEN:
			return "WHEN";
		case EXPR_KIND_PARTITION_BOUND:
			return "partition bound";
		case EXPR_KIND_PARTITION_EXPRESSION:
			return "PARTITION BY";
		case EXPR_KIND_CALL_ARGUMENT:
			return "CALL";
		case EXPR_KIND_COPY_WHERE:
			return "WHERE";
		case EXPR_KIND_GENERATED_COLUMN:
			return "GENERATED AS";
		case EXPR_KIND_CYCLE_MARK:
			return "CYCLE";

			/*
			 * There is intentionally no default: case here, so that the
			 * compiler will warn if we add a new ParseExprKind without
			 * extending this switch.  If we do see an unrecognized value at
			 * runtime, we'll fall through to the "unrecognized" return.
			 */
	}
	return "unrecognized expression kind";
}

/*
 * Make string Const node from JSON encoding name.
 *
 * UTF8 is default encoding.
 */
static Const *
getJsonEncodingConst(JsonFormat *format)
{
	JsonEncoding encoding;
	const char *enc;
	Name		encname = palloc(sizeof(NameData));

	if (!format ||
		format->format_type == JS_FORMAT_DEFAULT ||
		format->encoding == JS_ENC_DEFAULT)
		encoding = JS_ENC_UTF8;
	else
		encoding = format->encoding;

	switch (encoding)
	{
		case JS_ENC_UTF16:
			enc = "UTF16";
			break;
		case JS_ENC_UTF32:
			enc = "UTF32";
			break;
		case JS_ENC_UTF8:
			enc = "UTF8";
			break;
		default:
			elog(ERROR, "invalid JSON encoding: %d", encoding);
			break;
	}

	namestrcpy(encname, enc);

	return makeConst(NAMEOID, -1, InvalidOid, NAMEDATALEN,
					 NameGetDatum(encname), false, false);
}

/*
 * Make bytea => text conversion using specified JSON format encoding.
 */
static Node *
makeJsonByteaToTextConversion(Node *expr, JsonFormat *format, int location)
{
	Const	   *encoding = getJsonEncodingConst(format);
	FuncExpr   *fexpr = makeFuncExpr(F_CONVERT_FROM, TEXTOID,
									 list_make2(expr, encoding),
									 InvalidOid, InvalidOid,
									 COERCE_EXPLICIT_CALL);

	fexpr->location = location;

	return (Node *) fexpr;
}

/*
 * Transform JSON value expression using specified input JSON format or
 * default format otherwise, coercing to the targettype if needed.
 *
 * Returned expression is either ve->raw_expr coerced to text (if needed) or
 * a JsonValueExpr with formatted_expr set to the coerced copy of raw_expr
 * if the specified format and the targettype requires it.
 */
static Node *
transformJsonValueExpr(ParseState *pstate, const char *constructName,
					   JsonValueExpr *ve, JsonFormatType default_format,
					   Oid targettype, bool isarg)
{
	Node	   *expr = transformExprRecurse(pstate, (Node *) ve->raw_expr);
	Node	   *rawexpr;
	JsonFormatType format;
	Oid			exprtype;
	int			location;
	char		typcategory;
	bool		typispreferred;

	if (exprType(expr) == UNKNOWNOID)
		expr = coerce_to_specific_type(pstate, expr, TEXTOID, constructName);

	rawexpr = expr;
	exprtype = exprType(expr);
	location = exprLocation(expr);

	get_type_category_preferred(exprtype, &typcategory, &typispreferred);

	if (ve->format->format_type != JS_FORMAT_DEFAULT)
	{
		if (ve->format->encoding != JS_ENC_DEFAULT && exprtype != BYTEAOID)
			ereport(ERROR,
					errcode(ERRCODE_DATATYPE_MISMATCH),
					errmsg("JSON ENCODING clause is only allowed for bytea input type"),
					parser_errposition(pstate, ve->format->location));

		if (exprtype == JSONOID || exprtype == JSONBOID)
			format = JS_FORMAT_DEFAULT; /* do not format json[b] types */
		else
			format = ve->format->format_type;
	}
	else if (isarg)
	{
		/*
		 * Special treatment for PASSING arguments.
		 *
		 * Pass types supported by GetJsonPathVar() / JsonItemFromDatum()
		 * directly without converting to json[b].
		 */
		switch (exprtype)
		{
			case BOOLOID:
			case NUMERICOID:
			case INT2OID:
			case INT4OID:
			case INT8OID:
			case FLOAT4OID:
			case FLOAT8OID:
			case TEXTOID:
			case VARCHAROID:
			case DATEOID:
			case TIMEOID:
			case TIMETZOID:
			case TIMESTAMPOID:
			case TIMESTAMPTZOID:
				return expr;

			default:
				if (typcategory == TYPCATEGORY_STRING)
					return expr;
				/* else convert argument to json[b] type */
				break;
		}

		format = default_format;
	}
	else if (exprtype == JSONOID || exprtype == JSONBOID)
		format = JS_FORMAT_DEFAULT; /* do not format json[b] types */
	else
		format = default_format;

	if (format != JS_FORMAT_DEFAULT ||
		(OidIsValid(targettype) && exprtype != targettype))
	{
		Node	   *coerced;
		bool		only_allow_cast = OidIsValid(targettype);

		/*
		 * PASSING args are handled appropriately by GetJsonPathVar() /
		 * JsonItemFromDatum().
		 */
		if (!isarg &&
			!only_allow_cast &&
			exprtype != BYTEAOID && typcategory != TYPCATEGORY_STRING)
			ereport(ERROR,
					errcode(ERRCODE_DATATYPE_MISMATCH),
					ve->format->format_type == JS_FORMAT_DEFAULT ?
					errmsg("cannot use non-string types with implicit FORMAT JSON clause") :
					errmsg("cannot use non-string types with explicit FORMAT JSON clause"),
					parser_errposition(pstate, ve->format->location >= 0 ?
									   ve->format->location : location));

		/* Convert encoded JSON text from bytea. */
		if (format == JS_FORMAT_JSON && exprtype == BYTEAOID)
		{
			expr = makeJsonByteaToTextConversion(expr, ve->format, location);
			exprtype = TEXTOID;
		}

		if (!OidIsValid(targettype))
			targettype = format == JS_FORMAT_JSONB ? JSONBOID : JSONOID;

		/* Try to coerce to the target type. */
		coerced = coerce_to_target_type(pstate, expr, exprtype,
										targettype, -1,
										COERCION_EXPLICIT,
										COERCE_EXPLICIT_CAST,
										location);

		if (!coerced)
		{
			/* If coercion failed, use to_json()/to_jsonb() functions. */
			FuncExpr   *fexpr;
			Oid			fnoid;

			/*
			 * Though only allow a cast when the target type is specified by
			 * the caller.
			 */
			if (only_allow_cast)
				ereport(ERROR,
						(errcode(ERRCODE_CANNOT_COERCE),
						 errmsg("cannot cast type %s to %s",
								format_type_be(exprtype),
								format_type_be(targettype)),
						 parser_errposition(pstate, location)));

			fnoid = targettype == JSONOID ? F_TO_JSON : F_TO_JSONB;
			fexpr = makeFuncExpr(fnoid, targettype, list_make1(expr),
								 InvalidOid, InvalidOid, COERCE_EXPLICIT_CALL);

			fexpr->location = location;

			coerced = (Node *) fexpr;
		}

		if (coerced == expr)
			expr = rawexpr;
		else
		{
			ve = copyObject(ve);
			ve->raw_expr = (Expr *) rawexpr;
			ve->formatted_expr = (Expr *) coerced;

			expr = (Node *) ve;
		}
	}

	/* If returning a JsonValueExpr, formatted_expr must have been set. */
	Assert(!IsA(expr, JsonValueExpr) ||
		   ((JsonValueExpr *) expr)->formatted_expr != NULL);

	return expr;
}

/*
 * Checks specified output format for its applicability to the target type.
 */
static void
checkJsonOutputFormat(ParseState *pstate, const JsonFormat *format,
					  Oid targettype, bool allow_format_for_non_strings)
{
	if (!allow_format_for_non_strings &&
		format->format_type != JS_FORMAT_DEFAULT &&
		(targettype != BYTEAOID &&
		 targettype != JSONOID &&
		 targettype != JSONBOID))
	{
		char		typcategory;
		bool		typispreferred;

		get_type_category_preferred(targettype, &typcategory, &typispreferred);

		if (typcategory != TYPCATEGORY_STRING)
			ereport(ERROR,
					errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					parser_errposition(pstate, format->location),
					errmsg("cannot use JSON format with non-string output types"));
	}

	if (format->format_type == JS_FORMAT_JSON)
	{
		JsonEncoding enc = format->encoding != JS_ENC_DEFAULT ?
			format->encoding : JS_ENC_UTF8;

		if (targettype != BYTEAOID &&
			format->encoding != JS_ENC_DEFAULT)
			ereport(ERROR,
					errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					parser_errposition(pstate, format->location),
					errmsg("cannot set JSON encoding for non-bytea output types"));

		if (enc != JS_ENC_UTF8)
			ereport(ERROR,
					errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					errmsg("unsupported JSON encoding"),
					errhint("Only UTF8 JSON encoding is supported."),
					parser_errposition(pstate, format->location));
	}
}

/*
 * Transform JSON output clause.
 *
 * Assigns target type oid and modifier.
 * Assigns default format or checks specified format for its applicability to
 * the target type.
 */
static JsonReturning *
transformJsonOutput(ParseState *pstate, const JsonOutput *output,
					bool allow_format)
{
	JsonReturning *ret;

	/* if output clause is not specified, make default clause value */
	if (!output)
	{
		ret = makeNode(JsonReturning);

		ret->format = makeJsonFormat(JS_FORMAT_DEFAULT, JS_ENC_DEFAULT, -1);
		ret->typid = InvalidOid;
		ret->typmod = -1;

		return ret;
	}

	ret = copyObject(output->returning);

	typenameTypeIdAndMod(pstate, output->typeName, &ret->typid, &ret->typmod);

	if (output->typeName->setof)
		ereport(ERROR,
				errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				errmsg("returning SETOF types is not supported in SQL/JSON functions"));

	if (get_typtype(ret->typid) == TYPTYPE_PSEUDO)
		ereport(ERROR,
				errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				errmsg("returning pseudo-types is not supported in SQL/JSON functions"));

	if (ret->format->format_type == JS_FORMAT_DEFAULT)
		/* assign JSONB format when returning jsonb, or JSON format otherwise */
		ret->format->format_type =
			ret->typid == JSONBOID ? JS_FORMAT_JSONB : JS_FORMAT_JSON;
	else
		checkJsonOutputFormat(pstate, ret->format, ret->typid, allow_format);

	return ret;
}

/*
 * Transform JSON output clause of JSON constructor functions.
 *
 * Derive RETURNING type, if not specified, from argument types.
 */
static JsonReturning *
transformJsonConstructorOutput(ParseState *pstate, JsonOutput *output,
							   List *args)
{
	JsonReturning *returning = transformJsonOutput(pstate, output, true);

	if (!OidIsValid(returning->typid))
	{
		ListCell   *lc;
		bool		have_jsonb = false;

		foreach(lc, args)
		{
			Node	   *expr = lfirst(lc);
			Oid			typid = exprType(expr);

			have_jsonb |= typid == JSONBOID;

			if (have_jsonb)
				break;
		}

		if (have_jsonb)
		{
			returning->typid = JSONBOID;
			returning->format->format_type = JS_FORMAT_JSONB;
		}
		else
		{
			/* XXX TEXT is default by the standard, but we return JSON */
			returning->typid = JSONOID;
			returning->format->format_type = JS_FORMAT_JSON;
		}

		returning->typmod = -1;
	}

	return returning;
}

/*
 * Coerce json[b]-valued function expression to the output type.
 */
static Node *
coerceJsonFuncExpr(ParseState *pstate, Node *expr,
				   const JsonReturning *returning, bool report_error)
{
	Node	   *res;
	int			location;
	Oid			exprtype = exprType(expr);

	/* if output type is not specified or equals to function type, return */
	if (!OidIsValid(returning->typid) || returning->typid == exprtype)
		return expr;

	location = exprLocation(expr);

	if (location < 0)
		location = returning->format->location;

	/* special case for RETURNING bytea FORMAT json */
	if (returning->format->format_type == JS_FORMAT_JSON &&
		returning->typid == BYTEAOID)
	{
		/* encode json text into bytea using pg_convert_to() */
		Node	   *texpr = coerce_to_specific_type(pstate, expr, TEXTOID,
													"JSON_FUNCTION");
		Const	   *enc = getJsonEncodingConst(returning->format);
		FuncExpr   *fexpr = makeFuncExpr(F_CONVERT_TO, BYTEAOID,
										 list_make2(texpr, enc),
										 InvalidOid, InvalidOid,
										 COERCE_EXPLICIT_CALL);

		fexpr->location = location;

		return (Node *) fexpr;
	}

	/*
	 * For other cases, try to coerce expression to the output type using
	 * assignment-level casts, erroring out if none available.  This basically
	 * allows coercing the jsonb value to any string type (typcategory = 'S').
	 *
	 * Requesting assignment-level here means that typmod / length coercion
	 * assumes implicit coercion which is the behavior we want; see
	 * build_coercion_expression().
	 */
	res = coerce_to_target_type(pstate, expr, exprtype,
								returning->typid, returning->typmod,
								COERCION_ASSIGNMENT,
								COERCE_IMPLICIT_CAST,
								location);

	if (!res && report_error)
		ereport(ERROR,
				errcode(ERRCODE_CANNOT_COERCE),
				errmsg("cannot cast type %s to %s",
					   format_type_be(exprtype),
					   format_type_be(returning->typid)),
				parser_coercion_errposition(pstate, location, expr));

	return res;
}

/*
 * Make a JsonConstructorExpr node.
 */
static Node *
makeJsonConstructorExpr(ParseState *pstate, JsonConstructorType type,
						List *args, Expr *fexpr, JsonReturning *returning,
						bool unique, bool absent_on_null, int location)
{
	JsonConstructorExpr *jsctor = makeNode(JsonConstructorExpr);
	Node	   *placeholder;
	Node	   *coercion;

	jsctor->args = args;
	jsctor->func = fexpr;
	jsctor->type = type;
	jsctor->returning = returning;
	jsctor->unique = unique;
	jsctor->absent_on_null = absent_on_null;
	jsctor->location = location;

	/*
	 * Coerce to the RETURNING type and format, if needed.  We abuse
	 * CaseTestExpr here as placeholder to pass the result of either
	 * evaluating 'fexpr' or whatever is produced by ExecEvalJsonConstructor()
	 * that is of type JSON or JSONB to the coercion function.
	 */
	if (fexpr)
	{
		CaseTestExpr *cte = makeNode(CaseTestExpr);

		cte->typeId = exprType((Node *) fexpr);
		cte->typeMod = exprTypmod((Node *) fexpr);
		cte->collation = exprCollation((Node *) fexpr);

		placeholder = (Node *) cte;
	}
	else
	{
		CaseTestExpr *cte = makeNode(CaseTestExpr);

		cte->typeId = returning->format->format_type == JS_FORMAT_JSONB ?
			JSONBOID : JSONOID;
		cte->typeMod = -1;
		cte->collation = InvalidOid;

		placeholder = (Node *) cte;
	}

	coercion = coerceJsonFuncExpr(pstate, placeholder, returning, true);

	if (coercion != placeholder)
		jsctor->coercion = (Expr *) coercion;

	return (Node *) jsctor;
}

/*
 * Transform JSON_OBJECT() constructor.
 *
 * JSON_OBJECT() is transformed into a JsonConstructorExpr node of type
 * JSCTOR_JSON_OBJECT.  The result is coerced to the target type given
 * by ctor->output.
 */
static Node *
transformJsonObjectConstructor(ParseState *pstate, JsonObjectConstructor *ctor)
{
	JsonReturning *returning;
	List	   *args = NIL;

	/* transform key-value pairs, if any */
	if (ctor->exprs)
	{
		ListCell   *lc;

		/* transform and append key-value arguments */
		foreach(lc, ctor->exprs)
		{
			JsonKeyValue *kv = castNode(JsonKeyValue, lfirst(lc));
			Node	   *key = transformExprRecurse(pstate, (Node *) kv->key);
			Node	   *val = transformJsonValueExpr(pstate, "JSON_OBJECT()",
													 kv->value,
													 JS_FORMAT_DEFAULT,
													 InvalidOid, false);

			args = lappend(args, key);
			args = lappend(args, val);
		}
	}

	returning = transformJsonConstructorOutput(pstate, ctor->output, args);

	return makeJsonConstructorExpr(pstate, JSCTOR_JSON_OBJECT, args, NULL,
								   returning, ctor->unique,
								   ctor->absent_on_null, ctor->location);
}

/*
 * Transform JSON_ARRAY(query [FORMAT] [RETURNING] [ON NULL]) into
 *  (SELECT  JSON_ARRAYAGG(a  [FORMAT] [RETURNING] [ON NULL]) FROM (query) q(a))
 */
static Node *
transformJsonArrayQueryConstructor(ParseState *pstate,
								   JsonArrayQueryConstructor *ctor)
{
	SubLink    *sublink = makeNode(SubLink);
	SelectStmt *select = makeNode(SelectStmt);
	RangeSubselect *range = makeNode(RangeSubselect);
	Alias	   *alias = makeNode(Alias);
	ResTarget  *target = makeNode(ResTarget);
	JsonArrayAgg *agg = makeNode(JsonArrayAgg);
	ColumnRef  *colref = makeNode(ColumnRef);
	Query	   *query;
	ParseState *qpstate;

	/* Transform query only for counting target list entries. */
	qpstate = make_parsestate(pstate);

	query = transformStmt(qpstate, copyObject(ctor->query));

	if (count_nonjunk_tlist_entries(query->targetList) != 1)
		ereport(ERROR,
				errcode(ERRCODE_SYNTAX_ERROR),
				errmsg("subquery must return only one column"),
				parser_errposition(pstate, ctor->location));

	free_parsestate(qpstate);

	colref->fields = list_make2(makeString(pstrdup("q")),
								makeString(pstrdup("a")));
	colref->location = ctor->location;

	/*
	 * No formatting necessary, so set formatted_expr to be the same as
	 * raw_expr.
	 */
	agg->arg = makeJsonValueExpr((Expr *) colref, (Expr *) colref,
								 ctor->format);
	agg->absent_on_null = ctor->absent_on_null;
	agg->constructor = makeNode(JsonAggConstructor);
	agg->constructor->agg_order = NIL;
	agg->constructor->output = ctor->output;
	agg->constructor->location = ctor->location;

	target->name = NULL;
	target->indirection = NIL;
	target->val = (Node *) agg;
	target->location = ctor->location;

	alias->aliasname = pstrdup("q");
	alias->colnames = list_make1(makeString(pstrdup("a")));

	range->lateral = false;
	range->subquery = ctor->query;
	range->alias = alias;

	select->targetList = list_make1(target);
	select->fromClause = list_make1(range);

	sublink->subLinkType = EXPR_SUBLINK;
	sublink->subLinkId = 0;
	sublink->testexpr = NULL;
	sublink->operName = NIL;
	sublink->subselect = (Node *) select;
	sublink->location = ctor->location;

	return transformExprRecurse(pstate, (Node *) sublink);
}

/*
 * Common code for JSON_OBJECTAGG and JSON_ARRAYAGG transformation.
 */
static Node *
transformJsonAggConstructor(ParseState *pstate, JsonAggConstructor *agg_ctor,
							JsonReturning *returning, List *args,
							Oid aggfnoid, Oid aggtype,
							JsonConstructorType ctor_type,
							bool unique, bool absent_on_null)
{
	Node	   *node;
	Expr	   *aggfilter;

	aggfilter = agg_ctor->agg_filter ? (Expr *)
		transformWhereClause(pstate, agg_ctor->agg_filter,
							 EXPR_KIND_FILTER, "FILTER") : NULL;

	if (agg_ctor->over)
	{
		/* window function */
		WindowFunc *wfunc = makeNode(WindowFunc);

		wfunc->winfnoid = aggfnoid;
		wfunc->wintype = aggtype;
		/* wincollid and inputcollid will be set by parse_collate.c */
		wfunc->args = args;
		wfunc->aggfilter = aggfilter;
		wfunc->runCondition = NIL;
		/* winref will be set by transformWindowFuncCall */
		wfunc->winstar = false;
		wfunc->winagg = true;
		wfunc->location = agg_ctor->location;

		/*
		 * ordered aggs not allowed in windows yet
		 */
		if (agg_ctor->agg_order != NIL)
			ereport(ERROR,
					errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					errmsg("aggregate ORDER BY is not implemented for window functions"),
					parser_errposition(pstate, agg_ctor->location));

		/* parse_agg.c does additional window-func-specific processing */
		transformWindowFuncCall(pstate, wfunc, agg_ctor->over);

		node = (Node *) wfunc;
	}
	else
	{
		Aggref	   *aggref = makeNode(Aggref);

		aggref->aggfnoid = aggfnoid;
		aggref->aggtype = aggtype;

		/* aggcollid and inputcollid will be set by parse_collate.c */
		/* aggtranstype will be set by planner */
		/* aggargtypes will be set by transformAggregateCall */
		/* aggdirectargs and args will be set by transformAggregateCall */
		/* aggorder and aggdistinct will be set by transformAggregateCall */
		aggref->aggfilter = aggfilter;
		aggref->aggstar = false;
		aggref->aggvariadic = false;
		aggref->aggkind = AGGKIND_NORMAL;
		aggref->aggpresorted = false;
		/* agglevelsup will be set by transformAggregateCall */
		aggref->aggsplit = AGGSPLIT_SIMPLE; /* planner might change this */
		aggref->aggno = -1;		/* planner will set aggno and aggtransno */
		aggref->aggtransno = -1;
		aggref->location = agg_ctor->location;

		transformAggregateCall(pstate, aggref, args, agg_ctor->agg_order, false);

		node = (Node *) aggref;
	}

	return makeJsonConstructorExpr(pstate, ctor_type, NIL, (Expr *) node,
								   returning, unique, absent_on_null,
								   agg_ctor->location);
}

/*
 * Transform JSON_OBJECTAGG() aggregate function.
 *
 * JSON_OBJECTAGG() is transformed into a JsonConstructorExpr node of type
 * JSCTOR_JSON_OBJECTAGG, which at runtime becomes a
 * json[b]_object_agg[_unique][_strict](agg->arg->key, agg->arg->value) call
 * depending on the output JSON format.  The result is coerced to the target
 * type given by agg->constructor->output.
 */
static Node *
transformJsonObjectAgg(ParseState *pstate, JsonObjectAgg *agg)
{
	JsonReturning *returning;
	Node	   *key;
	Node	   *val;
	List	   *args;
	Oid			aggfnoid;
	Oid			aggtype;

	key = transformExprRecurse(pstate, (Node *) agg->arg->key);
	val = transformJsonValueExpr(pstate, "JSON_OBJECTAGG()",
								 agg->arg->value,
								 JS_FORMAT_DEFAULT,
								 InvalidOid, false);
	args = list_make2(key, val);

	returning = transformJsonConstructorOutput(pstate, agg->constructor->output,
											   args);

	if (returning->format->format_type == JS_FORMAT_JSONB)
	{
		if (agg->absent_on_null)
			if (agg->unique)
				aggfnoid = F_JSONB_OBJECT_AGG_UNIQUE_STRICT;
			else
				aggfnoid = F_JSONB_OBJECT_AGG_STRICT;
		else if (agg->unique)
			aggfnoid = F_JSONB_OBJECT_AGG_UNIQUE;
		else
			aggfnoid = F_JSONB_OBJECT_AGG;

		aggtype = JSONBOID;
	}
	else
	{
		if (agg->absent_on_null)
			if (agg->unique)
				aggfnoid = F_JSON_OBJECT_AGG_UNIQUE_STRICT;
			else
				aggfnoid = F_JSON_OBJECT_AGG_STRICT;
		else if (agg->unique)
			aggfnoid = F_JSON_OBJECT_AGG_UNIQUE;
		else
			aggfnoid = F_JSON_OBJECT_AGG;

		aggtype = JSONOID;
	}

	return transformJsonAggConstructor(pstate, agg->constructor, returning,
									   args, aggfnoid, aggtype,
									   JSCTOR_JSON_OBJECTAGG,
									   agg->unique, agg->absent_on_null);
}

/*
 * Transform JSON_ARRAYAGG() aggregate function.
 *
 * JSON_ARRAYAGG() is transformed into a JsonConstructorExpr node of type
 * JSCTOR_JSON_ARRAYAGG, which at runtime becomes a
 * json[b]_object_agg[_unique][_strict](agg->arg) call depending on the output
 * JSON format.  The result is coerced to the target type given by
 * agg->constructor->output.
 */
static Node *
transformJsonArrayAgg(ParseState *pstate, JsonArrayAgg *agg)
{
	JsonReturning *returning;
	Node	   *arg;
	Oid			aggfnoid;
	Oid			aggtype;

	arg = transformJsonValueExpr(pstate, "JSON_ARRAYAGG()", agg->arg,
								 JS_FORMAT_DEFAULT, InvalidOid, false);

	returning = transformJsonConstructorOutput(pstate, agg->constructor->output,
											   list_make1(arg));

	if (returning->format->format_type == JS_FORMAT_JSONB)
	{
		aggfnoid = agg->absent_on_null ? F_JSONB_AGG_STRICT : F_JSONB_AGG;
		aggtype = JSONBOID;
	}
	else
	{
		aggfnoid = agg->absent_on_null ? F_JSON_AGG_STRICT : F_JSON_AGG;
		aggtype = JSONOID;
	}

	return transformJsonAggConstructor(pstate, agg->constructor, returning,
									   list_make1(arg), aggfnoid, aggtype,
									   JSCTOR_JSON_ARRAYAGG,
									   false, agg->absent_on_null);
}

/*
 * Transform JSON_ARRAY() constructor.
 *
 * JSON_ARRAY() is transformed into a JsonConstructorExpr node of type
 * JSCTOR_JSON_ARRAY.  The result is coerced to the target type given
 * by ctor->output.
 */
static Node *
transformJsonArrayConstructor(ParseState *pstate, JsonArrayConstructor *ctor)
{
	JsonReturning *returning;
	List	   *args = NIL;

	/* transform element expressions, if any */
	if (ctor->exprs)
	{
		ListCell   *lc;

		/* transform and append element arguments */
		foreach(lc, ctor->exprs)
		{
			JsonValueExpr *jsval = castNode(JsonValueExpr, lfirst(lc));
			Node	   *val = transformJsonValueExpr(pstate, "JSON_ARRAY()",
													 jsval, JS_FORMAT_DEFAULT,
													 InvalidOid, false);

			args = lappend(args, val);
		}
	}

	returning = transformJsonConstructorOutput(pstate, ctor->output, args);

	return makeJsonConstructorExpr(pstate, JSCTOR_JSON_ARRAY, args, NULL,
								   returning, false, ctor->absent_on_null,
								   ctor->location);
}

static Node *
transformJsonParseArg(ParseState *pstate, Node *jsexpr, JsonFormat *format,
					  Oid *exprtype)
{
	Node	   *raw_expr = transformExprRecurse(pstate, jsexpr);
	Node	   *expr = raw_expr;

	*exprtype = exprType(expr);

	/* prepare input document */
	if (*exprtype == BYTEAOID)
	{
		JsonValueExpr *jve;

		expr = raw_expr;
		expr = makeJsonByteaToTextConversion(expr, format, exprLocation(expr));
		*exprtype = TEXTOID;

		jve = makeJsonValueExpr((Expr *) raw_expr, (Expr *) expr, format);
		expr = (Node *) jve;
	}
	else
	{
		char		typcategory;
		bool		typispreferred;

		get_type_category_preferred(*exprtype, &typcategory, &typispreferred);

		if (*exprtype == UNKNOWNOID || typcategory == TYPCATEGORY_STRING)
		{
			expr = coerce_to_target_type(pstate, (Node *) expr, *exprtype,
										 TEXTOID, -1,
										 COERCION_IMPLICIT,
										 COERCE_IMPLICIT_CAST, -1);
			*exprtype = TEXTOID;
		}

		if (format->encoding != JS_ENC_DEFAULT)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 parser_errposition(pstate, format->location),
					 errmsg("cannot use JSON FORMAT ENCODING clause for non-bytea input types")));
	}

	return expr;
}

/*
 * Transform IS JSON predicate.
 */
static Node *
transformJsonIsPredicate(ParseState *pstate, JsonIsPredicate *pred)
{
	Oid			exprtype;
	Node	   *expr = transformJsonParseArg(pstate, pred->expr, pred->format,
											 &exprtype);

	/* make resulting expression */
	if (exprtype != TEXTOID && exprtype != JSONOID && exprtype != JSONBOID)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("cannot use type %s in IS JSON predicate",
						format_type_be(exprtype))));

	/* This intentionally(?) drops the format clause. */
	return makeJsonIsPredicate(expr, NULL, pred->item_type,
							   pred->unique_keys, pred->location);
}

/*
 * Transform the RETURNING clause of a JSON_*() expression if there is one and
 * create one if not.
 */
static JsonReturning *
transformJsonReturning(ParseState *pstate, JsonOutput *output, const char *fname)
{
	JsonReturning *returning;

	if (output)
	{
		returning = transformJsonOutput(pstate, output, false);

		Assert(OidIsValid(returning->typid));

		if (returning->typid != JSONOID && returning->typid != JSONBOID)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("cannot use type %s in RETURNING clause of %s",
							format_type_be(returning->typid), fname),
					 errhint("Try returning json or jsonb."),
					 parser_errposition(pstate, output->typeName->location)));
	}
	else
	{
		/* Output type is JSON by default. */
		Oid			targettype = JSONOID;
		JsonFormatType format = JS_FORMAT_JSON;

		returning = makeNode(JsonReturning);
		returning->format = makeJsonFormat(format, JS_ENC_DEFAULT, -1);
		returning->typid = targettype;
		returning->typmod = -1;
	}

	return returning;
}

/*
 * Transform a JSON() expression.
 *
 * JSON() is transformed into a JsonConstructorExpr of type JSCTOR_JSON_PARSE,
 * which validates the input expression value as JSON.
 */
static Node *
transformJsonParseExpr(ParseState *pstate, JsonParseExpr *jsexpr)
{
	JsonOutput *output = jsexpr->output;
	JsonReturning *returning;
	Node	   *arg;

	returning = transformJsonReturning(pstate, output, "JSON()");

	if (jsexpr->unique_keys)
	{
		/*
		 * Coerce string argument to text and then to json[b] in the executor
		 * node with key uniqueness check.
		 */
		JsonValueExpr *jve = jsexpr->expr;
		Oid			arg_type;

		arg = transformJsonParseArg(pstate, (Node *) jve->raw_expr, jve->format,
									&arg_type);

		if (arg_type != TEXTOID)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("cannot use non-string types with WITH UNIQUE KEYS clause"),
					 parser_errposition(pstate, jsexpr->location)));
	}
	else
	{
		/*
		 * Coerce argument to target type using CAST for compatibility with PG
		 * function-like CASTs.
		 */
		arg = transformJsonValueExpr(pstate, "JSON()", jsexpr->expr,
									 JS_FORMAT_JSON, returning->typid, false);
	}

	return makeJsonConstructorExpr(pstate, JSCTOR_JSON_PARSE, list_make1(arg), NULL,
								   returning, jsexpr->unique_keys, false,
								   jsexpr->location);
}

/*
 * Transform a JSON_SCALAR() expression.
 *
 * JSON_SCALAR() is transformed into a JsonConstructorExpr of type
 * JSCTOR_JSON_SCALAR, which converts the input SQL scalar value into
 * a json[b] value.
 */
static Node *
transformJsonScalarExpr(ParseState *pstate, JsonScalarExpr *jsexpr)
{
	Node	   *arg = transformExprRecurse(pstate, (Node *) jsexpr->expr);
	JsonOutput *output = jsexpr->output;
	JsonReturning *returning;

	returning = transformJsonReturning(pstate, output, "JSON_SCALAR()");

	if (exprType(arg) == UNKNOWNOID)
		arg = coerce_to_specific_type(pstate, arg, TEXTOID, "JSON_SCALAR");

	return makeJsonConstructorExpr(pstate, JSCTOR_JSON_SCALAR, list_make1(arg), NULL,
								   returning, false, false, jsexpr->location);
}

/*
 * Transform a JSON_SERIALIZE() expression.
 *
 * JSON_SERIALIZE() is transformed into a JsonConstructorExpr of type
 * JSCTOR_JSON_SERIALIZE which converts the input JSON value into a character
 * or bytea string.
 */
static Node *
transformJsonSerializeExpr(ParseState *pstate, JsonSerializeExpr *expr)
{
	JsonReturning *returning;
	Node	   *arg = transformJsonValueExpr(pstate, "JSON_SERIALIZE()",
											 expr->expr,
											 JS_FORMAT_JSON,
											 InvalidOid, false);

	if (expr->output)
	{
		returning = transformJsonOutput(pstate, expr->output, true);

		if (returning->typid != BYTEAOID)
		{
			char		typcategory;
			bool		typispreferred;

			get_type_category_preferred(returning->typid, &typcategory,
										&typispreferred);
			if (typcategory != TYPCATEGORY_STRING)
				ereport(ERROR,
						(errcode(ERRCODE_DATATYPE_MISMATCH),
						 errmsg("cannot use type %s in RETURNING clause of %s",
								format_type_be(returning->typid),
								"JSON_SERIALIZE()"),
						 errhint("Try returning a string type or bytea.")));
		}
	}
	else
	{
		/* RETURNING TEXT FORMAT JSON is by default */
		returning = makeNode(JsonReturning);
		returning->format = makeJsonFormat(JS_FORMAT_JSON, JS_ENC_DEFAULT, -1);
		returning->typid = TEXTOID;
		returning->typmod = -1;
	}

	return makeJsonConstructorExpr(pstate, JSCTOR_JSON_SERIALIZE, list_make1(arg),
								   NULL, returning, false, false, expr->location);
}

/*
 * Transform JSON_VALUE, JSON_QUERY, JSON_EXISTS, JSON_TABLE functions into
 * a JsonExpr node.
 */
static Node *
transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func)
{
	JsonExpr   *jsexpr;
	Node	   *path_spec;
	Oid			pathspec_type;
	int			pathspec_loc;
	Node	   *coerced_path_spec;
	const char *func_name = NULL;
	JsonFormatType default_format;

	switch (func->op)
	{
		case JSON_EXISTS_OP:
			func_name = "JSON_EXISTS";
			default_format = JS_FORMAT_DEFAULT;
			break;
		case JSON_QUERY_OP:
			func_name = "JSON_QUERY";
			default_format = JS_FORMAT_JSONB;
			break;
		case JSON_VALUE_OP:
			func_name = "JSON_VALUE";
			default_format = JS_FORMAT_DEFAULT;
			break;
		case JSON_TABLE_OP:
			func_name = "JSON_TABLE";
			default_format = JS_FORMAT_JSONB;
			break;
		default:
			elog(ERROR, "invalid JsonFuncExpr op %d", (int) func->op);
			default_format = JS_FORMAT_DEFAULT; /* keep compiler quiet */
			break;
	}

	/*
	 * Even though the syntax allows it, FORMAT JSON specification in
	 * RETURNING is meaningless except for JSON_QUERY().  Flag if not
	 * JSON_QUERY().
	 */
	if (func->output && func->op != JSON_QUERY_OP)
	{
		JsonFormat *format = func->output->returning->format;

		if (format->format_type != JS_FORMAT_DEFAULT ||
			format->encoding != JS_ENC_DEFAULT)
			ereport(ERROR,
					errcode(ERRCODE_SYNTAX_ERROR),
					errmsg("cannot specify FORMAT JSON in RETURNING clause of %s()",
						   func_name),
					parser_errposition(pstate, format->location));
	}

	/* OMIT QUOTES is meaningless when strings are wrapped. */
	if (func->op == JSON_QUERY_OP)
	{
		if (func->quotes == JS_QUOTES_OMIT &&
			(func->wrapper == JSW_CONDITIONAL ||
			 func->wrapper == JSW_UNCONDITIONAL))
			ereport(ERROR,
					errcode(ERRCODE_SYNTAX_ERROR),
					errmsg("SQL/JSON QUOTES behavior must not be specified when WITH WRAPPER is used"),
					parser_errposition(pstate, func->location));
		if (func->on_empty != NULL &&
			func->on_empty->btype != JSON_BEHAVIOR_ERROR &&
			func->on_empty->btype != JSON_BEHAVIOR_NULL &&
			func->on_empty->btype != JSON_BEHAVIOR_EMPTY &&
			func->on_empty->btype != JSON_BEHAVIOR_EMPTY_ARRAY &&
			func->on_empty->btype != JSON_BEHAVIOR_EMPTY_OBJECT &&
			func->on_empty->btype != JSON_BEHAVIOR_DEFAULT)
		{
			if (func->column_name == NULL)
				ereport(ERROR,
						errcode(ERRCODE_SYNTAX_ERROR),
				/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errmsg("invalid %s behavior", "ON EMPTY"),
				/*- translator: first %s is name of a SQL/JSON clause (eg. ON EMPTY),
					second %s is a SQL/JSON function name (e.g. JSON_QUERY) */
						errdetail("Only ERROR, NULL, EMPTY ARRAY, EMPTY OBJECT, or DEFAULT expression is allowed in %s for %s.",
								  "ON EMPTY", "JSON_QUERY()"),
						parser_errposition(pstate, func->on_empty->location));
			else
				ereport(ERROR,
						errcode(ERRCODE_SYNTAX_ERROR),
				/*- translator: first %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errmsg("invalid %s behavior for column \"%s\"",
							   "ON EMPTY", func->column_name),
				/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errdetail("Only ERROR, NULL, EMPTY ARRAY, EMPTY OBJECT, or DEFAULT expression is allowed in %s for formatted columns.",
								  "ON EMPTY"),
						parser_errposition(pstate, func->on_empty->location));
		}
		if (func->on_error != NULL &&
			func->on_error->btype != JSON_BEHAVIOR_ERROR &&
			func->on_error->btype != JSON_BEHAVIOR_NULL &&
			func->on_error->btype != JSON_BEHAVIOR_EMPTY &&
			func->on_error->btype != JSON_BEHAVIOR_EMPTY_ARRAY &&
			func->on_error->btype != JSON_BEHAVIOR_EMPTY_OBJECT &&
			func->on_error->btype != JSON_BEHAVIOR_DEFAULT)
		{
			if (func->column_name == NULL)
				ereport(ERROR,
						errcode(ERRCODE_SYNTAX_ERROR),
				/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errmsg("invalid %s behavior", "ON ERROR"),
				/*- translator: first %s is name of a SQL/JSON clause (eg. ON EMPTY),
					second %s is a SQL/JSON function name (e.g. JSON_QUERY) */
						errdetail("Only ERROR, NULL, EMPTY ARRAY, EMPTY OBJECT, or DEFAULT expression is allowed in %s for %s.",
								  "ON ERROR", "JSON_QUERY()"),
						parser_errposition(pstate, func->on_error->location));
			else
				ereport(ERROR,
						errcode(ERRCODE_SYNTAX_ERROR),
				/*- translator: first %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errmsg("invalid %s behavior for column \"%s\"",
							   "ON ERROR", func->column_name),
				/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errdetail("Only ERROR, NULL, EMPTY ARRAY, EMPTY OBJECT, or DEFAULT expression is allowed in %s for formatted columns.",
								  "ON ERROR"),
						parser_errposition(pstate, func->on_error->location));
		}
	}

	/* Check that ON ERROR/EMPTY behavior values are valid for the function. */
	if (func->op == JSON_EXISTS_OP &&
		func->on_error != NULL &&
		func->on_error->btype != JSON_BEHAVIOR_ERROR &&
		func->on_error->btype != JSON_BEHAVIOR_TRUE &&
		func->on_error->btype != JSON_BEHAVIOR_FALSE &&
		func->on_error->btype != JSON_BEHAVIOR_UNKNOWN)
	{
		if (func->column_name == NULL)
			ereport(ERROR,
					errcode(ERRCODE_SYNTAX_ERROR),
			/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
					errmsg("invalid %s behavior", "ON ERROR"),
					errdetail("Only ERROR, TRUE, FALSE, or UNKNOWN is allowed in %s for %s.",
							  "ON ERROR", "JSON_EXISTS()"),
					parser_errposition(pstate, func->on_error->location));
		else
			ereport(ERROR,
					errcode(ERRCODE_SYNTAX_ERROR),
			/*- translator: first %s is name a SQL/JSON clause (eg. ON EMPTY) */
					errmsg("invalid %s behavior for column \"%s\"",
						   "ON ERROR", func->column_name),
			/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
					errdetail("Only ERROR, TRUE, FALSE, or UNKNOWN is allowed in %s for EXISTS columns.",
							  "ON ERROR"),
					parser_errposition(pstate, func->on_error->location));
	}
	if (func->op == JSON_VALUE_OP)
	{
		if (func->on_empty != NULL &&
			func->on_empty->btype != JSON_BEHAVIOR_ERROR &&
			func->on_empty->btype != JSON_BEHAVIOR_NULL &&
			func->on_empty->btype != JSON_BEHAVIOR_DEFAULT)
		{
			if (func->column_name == NULL)
				ereport(ERROR,
						errcode(ERRCODE_SYNTAX_ERROR),
				/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errmsg("invalid %s behavior", "ON EMPTY"),
				/*- translator: first %s is name of a SQL/JSON clause (eg. ON EMPTY),
					second %s is a SQL/JSON function name (e.g. JSON_QUERY) */
						errdetail("Only ERROR, NULL, or DEFAULT expression is allowed in %s for %s.",
								  "ON EMPTY", "JSON_VALUE()"),
						parser_errposition(pstate, func->on_empty->location));
			else
				ereport(ERROR,
						errcode(ERRCODE_SYNTAX_ERROR),
				/*- translator: first %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errmsg("invalid %s behavior for column \"%s\"",
							   "ON EMPTY", func->column_name),
				/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errdetail("Only ERROR, NULL, or DEFAULT expression is allowed in %s for scalar columns.",
								  "ON EMPTY"),
						parser_errposition(pstate, func->on_empty->location));
		}
		if (func->on_error != NULL &&
			func->on_error->btype != JSON_BEHAVIOR_ERROR &&
			func->on_error->btype != JSON_BEHAVIOR_NULL &&
			func->on_error->btype != JSON_BEHAVIOR_DEFAULT)
		{
			if (func->column_name == NULL)
				ereport(ERROR,
						errcode(ERRCODE_SYNTAX_ERROR),
				/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errmsg("invalid %s behavior", "ON ERROR"),
				/*- translator: first %s is name of a SQL/JSON clause (eg. ON EMPTY),
					second %s is a SQL/JSON function name (e.g. JSON_QUERY) */
						errdetail("Only ERROR, NULL, or DEFAULT expression is allowed in %s for %s.",
								  "ON ERROR", "JSON_VALUE()"),
						parser_errposition(pstate, func->on_error->location));
			else
				ereport(ERROR,
						errcode(ERRCODE_SYNTAX_ERROR),
				/*- translator: first %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errmsg("invalid %s behavior for column \"%s\"",
							   "ON ERROR", func->column_name),
				/*- translator: %s is name of a SQL/JSON clause (eg. ON EMPTY) */
						errdetail("Only ERROR, NULL, or DEFAULT expression is allowed in %s for scalar columns.",
								  "ON ERROR"),
						parser_errposition(pstate, func->on_error->location));
		}
	}

	jsexpr = makeNode(JsonExpr);
	jsexpr->location = func->location;
	jsexpr->op = func->op;
	jsexpr->column_name = func->column_name;

	/*
	 * jsonpath machinery can only handle jsonb documents, so coerce the input
	 * if not already of jsonb type.
	 */
	jsexpr->formatted_expr = transformJsonValueExpr(pstate, func_name,
													func->context_item,
													default_format,
													JSONBOID,
													false);
	jsexpr->format = func->context_item->format;

	path_spec = transformExprRecurse(pstate, func->pathspec);
	pathspec_type = exprType(path_spec);
	pathspec_loc = exprLocation(path_spec);
	coerced_path_spec = coerce_to_target_type(pstate, path_spec,
											  pathspec_type,
											  JSONPATHOID, -1,
											  COERCION_EXPLICIT,
											  COERCE_IMPLICIT_CAST,
											  pathspec_loc);
	if (coerced_path_spec == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("JSON path expression must be of type %s, not of type %s",
						"jsonpath", format_type_be(pathspec_type)),
				 parser_errposition(pstate, pathspec_loc)));
	jsexpr->path_spec = coerced_path_spec;

	/* Transform and coerce the PASSING arguments to jsonb. */
	transformJsonPassingArgs(pstate, func_name,
							 JS_FORMAT_JSONB,
							 func->passing,
							 &jsexpr->passing_values,
							 &jsexpr->passing_names);

	/* Transform the JsonOutput into JsonReturning. */
	jsexpr->returning = transformJsonOutput(pstate, func->output, false);

	switch (func->op)
	{
		case JSON_EXISTS_OP:
			/* JSON_EXISTS returns boolean by default. */
			if (!OidIsValid(jsexpr->returning->typid))
			{
				jsexpr->returning->typid = BOOLOID;
				jsexpr->returning->typmod = -1;
				jsexpr->collation = InvalidOid;
			}

			/* JSON_TABLE() COLUMNS can specify a non-boolean type. */
			if (jsexpr->returning->typid != BOOLOID)
				jsexpr->use_json_coercion = true;

			jsexpr->on_error = transformJsonBehavior(pstate,
													 jsexpr,
													 func->on_error,
													 JSON_BEHAVIOR_FALSE,
													 jsexpr->returning);
			break;

		case JSON_QUERY_OP:
			/* JSON_QUERY returns jsonb by default. */
			if (!OidIsValid(jsexpr->returning->typid))
			{
				JsonReturning *ret = jsexpr->returning;

				ret->typid = JSONBOID;
				ret->typmod = -1;
			}

			jsexpr->collation = get_typcollation(jsexpr->returning->typid);

			/*
			 * Keep quotes on scalar strings by default, omitting them only if
			 * OMIT QUOTES is specified.
			 */
			jsexpr->omit_quotes = (func->quotes == JS_QUOTES_OMIT);
			jsexpr->wrapper = func->wrapper;

			/*
			 * Set up to coerce the result value of JsonPathValue() to the
			 * RETURNING type (default or user-specified), if needed.  Also if
			 * OMIT QUOTES is specified.
			 */
			if (jsexpr->returning->typid != JSONBOID || jsexpr->omit_quotes)
				jsexpr->use_json_coercion = true;

			/* Assume NULL ON EMPTY when ON EMPTY is not specified. */
			jsexpr->on_empty = transformJsonBehavior(pstate,
													 jsexpr,
													 func->on_empty,
													 JSON_BEHAVIOR_NULL,
													 jsexpr->returning);
			/* Assume NULL ON ERROR when ON ERROR is not specified. */
			jsexpr->on_error = transformJsonBehavior(pstate,
													 jsexpr,
													 func->on_error,
													 JSON_BEHAVIOR_NULL,
													 jsexpr->returning);
			break;

		case JSON_VALUE_OP:
			/* JSON_VALUE returns text by default. */
			if (!OidIsValid(jsexpr->returning->typid))
			{
				jsexpr->returning->typid = TEXTOID;
				jsexpr->returning->typmod = -1;
			}
			jsexpr->collation = get_typcollation(jsexpr->returning->typid);

			/*
			 * Override whatever transformJsonOutput() set these to, which
			 * assumes that output type to be jsonb.
			 */
			jsexpr->returning->format->format_type = JS_FORMAT_DEFAULT;
			jsexpr->returning->format->encoding = JS_ENC_DEFAULT;

			/* Always omit quotes from scalar strings. */
			jsexpr->omit_quotes = true;

			/*
			 * Set up to coerce the result value of JsonPathValue() to the
			 * RETURNING type (default or user-specified), if needed.
			 */
			if (jsexpr->returning->typid != TEXTOID)
			{
				if (get_typtype(jsexpr->returning->typid) == TYPTYPE_DOMAIN &&
					DomainHasConstraints(jsexpr->returning->typid))
					jsexpr->use_json_coercion = true;
				else
					jsexpr->use_io_coercion = true;
			}

			/* Assume NULL ON EMPTY when ON EMPTY is not specified. */
			jsexpr->on_empty = transformJsonBehavior(pstate,
													 jsexpr,
													 func->on_empty,
													 JSON_BEHAVIOR_NULL,
													 jsexpr->returning);
			/* Assume NULL ON ERROR when ON ERROR is not specified. */
			jsexpr->on_error = transformJsonBehavior(pstate,
													 jsexpr,
													 func->on_error,
													 JSON_BEHAVIOR_NULL,
													 jsexpr->returning);
			break;

		case JSON_TABLE_OP:
			if (!OidIsValid(jsexpr->returning->typid))
			{
				jsexpr->returning->typid = exprType(jsexpr->formatted_expr);
				jsexpr->returning->typmod = -1;
			}
			jsexpr->collation = get_typcollation(jsexpr->returning->typid);

			/*
			 * Assume EMPTY ARRAY ON ERROR when ON ERROR is not specified.
			 *
			 * ON EMPTY cannot be specified at the top level but it can be for
			 * the individual columns.
			 */
			jsexpr->on_error = transformJsonBehavior(pstate,
													 jsexpr,
													 func->on_error,
													 JSON_BEHAVIOR_EMPTY_ARRAY,
													 jsexpr->returning);
			break;

		default:
			elog(ERROR, "invalid JsonFuncExpr op %d", (int) func->op);
			break;
	}

	return (Node *) jsexpr;
}

/*
 * Transform a SQL/JSON PASSING clause.
 */
static void
transformJsonPassingArgs(ParseState *pstate, const char *constructName,
						 JsonFormatType format, List *args,
						 List **passing_values, List **passing_names)
{
	ListCell   *lc;

	*passing_values = NIL;
	*passing_names = NIL;

	foreach(lc, args)
	{
		JsonArgument *arg = castNode(JsonArgument, lfirst(lc));
		Node	   *expr = transformJsonValueExpr(pstate, constructName,
												  arg->val, format,
												  InvalidOid, true);

		*passing_values = lappend(*passing_values, expr);
		*passing_names = lappend(*passing_names, makeString(arg->name));
	}
}

/*
 * Recursively checks if the given expression, or its sub-node in some cases,
 * is valid for using as an ON ERROR / ON EMPTY DEFAULT expression.
 */
static bool
ValidJsonBehaviorDefaultExpr(Node *expr, void *context)
{
	if (expr == NULL)
		return false;

	switch (nodeTag(expr))
	{
			/* Acceptable expression nodes */
		case T_Const:
		case T_FuncExpr:
		case T_OpExpr:
			return true;

			/* Acceptable iff arg of the following nodes is one of the above */
		case T_CoerceViaIO:
		case T_CoerceToDomain:
		case T_ArrayCoerceExpr:
		case T_ConvertRowtypeExpr:
		case T_RelabelType:
		case T_CollateExpr:
			return expression_tree_walker(expr, ValidJsonBehaviorDefaultExpr,
										  context);
		default:
			break;
	}

	return false;
}

/*
 * Transform a JSON BEHAVIOR clause.
 */
static JsonBehavior *
transformJsonBehavior(ParseState *pstate, JsonExpr *jsexpr,
					  JsonBehavior *behavior,
					  JsonBehaviorType default_behavior,
					  JsonReturning *returning)
{
	JsonBehaviorType btype = default_behavior;
	Node	   *expr = NULL;
	bool		coerce_at_runtime = false;
	int			location = -1;

	if (behavior)
	{
		btype = behavior->btype;
		location = behavior->location;
		if (btype == JSON_BEHAVIOR_DEFAULT)
		{
			Oid			targetcoll = jsexpr->collation;
			Oid			exprcoll;

			expr = transformExprRecurse(pstate, behavior->expr);

			if (!ValidJsonBehaviorDefaultExpr(expr, NULL))
				ereport(ERROR,
						(errcode(ERRCODE_DATATYPE_MISMATCH),
						 errmsg("can only specify a constant, non-aggregate function, or operator expression for DEFAULT"),
						 parser_errposition(pstate, exprLocation(expr))));
			if (contain_var_clause(expr))
				ereport(ERROR,
						(errcode(ERRCODE_DATATYPE_MISMATCH),
						 errmsg("DEFAULT expression must not contain column references"),
						 parser_errposition(pstate, exprLocation(expr))));
			if (expression_returns_set(expr))
				ereport(ERROR,
						(errcode(ERRCODE_DATATYPE_MISMATCH),
						 errmsg("DEFAULT expression must not return a set"),
						 parser_errposition(pstate, exprLocation(expr))));

			/*
			 * Reject a DEFAULT expression whose collation differs from the
			 * enclosing JSON expression's result collation
			 * (jsexpr->collation), as chosen by the RETURNING clause.
			 */
			exprcoll = exprCollation(expr);
			if (!OidIsValid(exprcoll))
				exprcoll = get_typcollation(exprType(expr));
			if (OidIsValid(targetcoll) && OidIsValid(exprcoll) &&
				targetcoll != exprcoll)
				ereport(ERROR,
						errcode(ERRCODE_COLLATION_MISMATCH),
						errmsg("collation of DEFAULT expression conflicts with RETURNING clause"),
						errdetail("\"%s\" versus \"%s\"",
								  get_collation_name(exprcoll),
								  get_collation_name(targetcoll)),
						parser_errposition(pstate, exprLocation(expr)));
		}
	}

	if (expr == NULL && btype != JSON_BEHAVIOR_ERROR)
		expr = GetJsonBehaviorConst(btype, location);

	/*
	 * Try to coerce the expression if needed.
	 *
	 * Use runtime coercion using json_populate_type() if the expression is
	 * NULL, jsonb-valued, or boolean-valued (unless the target type is
	 * integer or domain over integer, in which case use the
	 * boolean-to-integer cast function).
	 *
	 * For other non-NULL expressions, try to find a cast and error out if one
	 * is not found.
	 */
	if (expr && exprType(expr) != returning->typid)
	{
		bool		isnull = (IsA(expr, Const) && ((Const *) expr)->constisnull);

		if (isnull ||
			exprType(expr) == JSONBOID ||
			(exprType(expr) == BOOLOID &&
			 getBaseType(returning->typid) != INT4OID))
		{
			coerce_at_runtime = true;

			/*
			 * json_populate_type() expects to be passed a jsonb value, so gin
			 * up a Const containing the appropriate boolean value represented
			 * as jsonb, discarding the original Const containing a plain
			 * boolean.
			 */
			if (exprType(expr) == BOOLOID)
			{
				char	   *val = btype == JSON_BEHAVIOR_TRUE ? "true" : "false";

				expr = (Node *) makeConst(JSONBOID, -1, InvalidOid, -1,
										  DirectFunctionCall1(jsonb_in,
															  CStringGetDatum(val)),
										  false, false);
			}
		}
		else
		{
			Node	   *coerced_expr;
			char		typcategory = TypeCategory(returning->typid);

			/*
			 * Use an assignment cast if coercing to a string type so that
			 * build_coercion_expression() assumes implicit coercion when
			 * coercing the typmod, so that inputs exceeding length cause an
			 * error instead of silent truncation.
			 */
			coerced_expr =
				coerce_to_target_type(pstate, expr, exprType(expr),
									  returning->typid, returning->typmod,
									  (typcategory == TYPCATEGORY_STRING ||
									   typcategory == TYPCATEGORY_BITSTRING) ?
									  COERCION_ASSIGNMENT :
									  COERCION_EXPLICIT,
									  COERCE_EXPLICIT_CAST,
									  exprLocation((Node *) behavior));

			if (coerced_expr == NULL)
			{
				/*
				 * Provide a HINT if the expression comes from a DEFAULT
				 * clause.
				 */
				if (btype == JSON_BEHAVIOR_DEFAULT)
					ereport(ERROR,
							errcode(ERRCODE_CANNOT_COERCE),
							errmsg("cannot cast behavior expression of type %s to %s",
								   format_type_be(exprType(expr)),
								   format_type_be(returning->typid)),
							errhint("You will need to explicitly cast the expression to type %s.",
									format_type_be(returning->typid)),
							parser_errposition(pstate, exprLocation(expr)));
				else
					ereport(ERROR,
							errcode(ERRCODE_CANNOT_COERCE),
							errmsg("cannot cast behavior expression of type %s to %s",
								   format_type_be(exprType(expr)),
								   format_type_be(returning->typid)),
							parser_errposition(pstate, exprLocation(expr)));
			}

			expr = coerced_expr;
		}
	}

	if (behavior)
		behavior->expr = expr;
	else
		behavior = makeJsonBehavior(btype, expr, location);

	behavior->coerce = coerce_at_runtime;

	return behavior;
}

/*
 * Returns a Const node holding the value for the given non-ERROR
 * JsonBehaviorType.
 */
static Node *
GetJsonBehaviorConst(JsonBehaviorType btype, int location)
{
	Datum		val = (Datum) 0;
	Oid			typid = JSONBOID;
	int			len = -1;
	bool		isbyval = false;
	bool		isnull = false;
	Const	   *con;

	switch (btype)
	{
		case JSON_BEHAVIOR_EMPTY_ARRAY:
			val = DirectFunctionCall1(jsonb_in, CStringGetDatum("[]"));
			break;

		case JSON_BEHAVIOR_EMPTY_OBJECT:
			val = DirectFunctionCall1(jsonb_in, CStringGetDatum("{}"));
			break;

		case JSON_BEHAVIOR_TRUE:
			val = BoolGetDatum(true);
			typid = BOOLOID;
			len = sizeof(bool);
			isbyval = true;
			break;

		case JSON_BEHAVIOR_FALSE:
			val = BoolGetDatum(false);
			typid = BOOLOID;
			len = sizeof(bool);
			isbyval = true;
			break;

		case JSON_BEHAVIOR_NULL:
		case JSON_BEHAVIOR_UNKNOWN:
		case JSON_BEHAVIOR_EMPTY:
			val = (Datum) 0;
			isnull = true;
			typid = INT4OID;
			len = sizeof(int32);
			isbyval = true;
			break;

			/* These two behavior types are handled by the caller. */
		case JSON_BEHAVIOR_DEFAULT:
		case JSON_BEHAVIOR_ERROR:
			Assert(false);
			break;

		default:
			elog(ERROR, "unrecognized SQL/JSON behavior %d", btype);
			break;
	}

	con = makeConst(typid, -1, InvalidOid, len, val, isnull, isbyval);
	con->location = location;

	return (Node *) con;
}
