Re-allow SRFs and window functions within sub-selects within aggregates.

check_agg_arguments_walker threw an error upon seeing a SRF or window
function, but that is too aggressive: if the function is within a
sub-select then it's perfectly fine.  I broke the SRF case in commit
0436f6bd by copying the logic for window functions ... but that was
broken too, and had been since commit eaccfded.

Repair both cases in HEAD, and the window function case back to 9.3.
9.2 gets this right.

src/backend/parser/parse_agg.c

@@ -705,7 +705,14 @@ check_agg_arguments_walker(Node *node,
 		}
 		/* Continue and descend into subtree */
 	}
-	/* We can throw error on sight for a set-returning function */
+
+	/*
+	 * SRFs and window functions can be rejected immediately, unless we are
+	 * within a sub-select within the aggregate's arguments; in that case
+	 * they're OK.
+	 */
+	if (context->sublevels_up == 0)
+	{
 		if ((IsA(node, FuncExpr) &&((FuncExpr *) node)->funcretset) ||
 			(IsA(node, OpExpr) &&((OpExpr *) node)->opretset))
 			ereport(ERROR,
@@ -713,13 +720,13 @@ check_agg_arguments_walker(Node *node,
 					 errmsg("aggregate function calls cannot contain set-returning function calls"),
 					 errhint("You might be able to move the set-returning function into a LATERAL FROM item."),
 					 parser_errposition(context->pstate, exprLocation(node))));
-	/* We can throw error on sight for a window function */
 		if (IsA(node, WindowFunc))
 			ereport(ERROR,
 					(errcode(ERRCODE_GROUPING_ERROR),
 					 errmsg("aggregate function calls cannot contain window function calls"),
 					 parser_errposition(context->pstate,
 										((WindowFunc *) node)->location)));
+	}
 	if (IsA(node, Query))
 	{
 		/* Recurse into subselects */

src/test/regress/expected/tsrf.out

@@ -212,6 +212,20 @@ ERROR:  aggregate function calls cannot contain set-returning function calls
 LINE 1: SELECT min(generate_series(1, 3)) FROM few;
                    ^
 HINT:  You might be able to move the set-returning function into a LATERAL FROM item.
+-- ... unless they're within a sub-select
+SELECT sum((3 = ANY(SELECT generate_series(1,4)))::int);
+ sum 
+-----
+   1
+(1 row)
+
+SELECT sum((3 = ANY(SELECT lag(x) over(order by x)
+                    FROM generate_series(1,4) x))::int);
+ sum 
+-----
+   1
+(1 row)
+
 -- SRFs are not allowed in window function arguments, either
 SELECT min(generate_series(1, 3)) OVER() FROM few;
 ERROR:  window function calls cannot contain set-returning function calls

src/test/regress/sql/tsrf.sql

@@ -61,6 +61,12 @@ SELECT q1, coalesce(generate_series(1,3), 0) FROM int8_tbl;
 -- SRFs are not allowed in aggregate arguments
 SELECT min(generate_series(1, 3)) FROM few;
 
+-- ... unless they're within a sub-select
+SELECT sum((3 = ANY(SELECT generate_series(1,4)))::int);
+
+SELECT sum((3 = ANY(SELECT lag(x) over(order by x)
+                    FROM generate_series(1,4) x))::int);
+
 -- SRFs are not allowed in window function arguments, either
 SELECT min(generate_series(1, 3)) OVER() FROM few;