diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 4cb1744da6..c334daae39 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -760,6 +760,12 @@ expression_returns_set_walker(Node *node, void *context)
 		/* else fall through to check args */
 	}
 
+	/*
+	 * If you add any more cases that return sets, also fix
+	 * expression_returns_set_rows() in clauses.c and IS_SRF_CALL() in
+	 * tlist.c.
+	 */
+
 	/* Avoid recursion for some cases that parser checks not to return a set */
 	if (IsA(node, Aggref))
 		return false;
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index 60c0e3f108..7991295548 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -986,7 +986,7 @@ relation_can_be_sorted_early(PlannerInfo *root, RelOptInfo *rel,
 		 * one are effectively checking properties of targetexpr, so there's
 		 * no point in asking whether some other EC member would be better.)
 		 */
-		if (IS_SRF_CALL((Node *) em->em_expr))
+		if (expression_returns_set((Node *) em->em_expr))
 			continue;
 
 		/*
@@ -1014,7 +1014,7 @@ relation_can_be_sorted_early(PlannerInfo *root, RelOptInfo *rel,
 	 * member in this case; since SRFs can't appear in WHERE, they cannot
 	 * belong to multi-member ECs.)
 	 */
-	if (IS_SRF_CALL((Node *) em->em_expr))
+	if (expression_returns_set((Node *) em->em_expr))
 		return false;
 
 	return true;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index fe9a9d7d89..784a1af82d 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -21,6 +21,17 @@
 #include "optimizer/tlist.h"
 
 
+/*
+ * Test if an expression node represents a SRF call.  Beware multiple eval!
+ *
+ * Please note that this is only meant for use in split_pathtarget_at_srfs();
+ * if you use it anywhere else, your code is almost certainly wrong for SRFs
+ * nested within expressions.  Use expression_returns_set() instead.
+ */
+#define IS_SRF_CALL(node) \
+	((IsA(node, FuncExpr) && ((FuncExpr *) (node))->funcretset) || \
+	 (IsA(node, OpExpr) && ((OpExpr *) (node))->opretset))
+
 /*
  * Data structures for split_pathtarget_at_srfs().  To preserve the identity
  * of sortgroupref items even if they are textually equal(), what we track is
diff --git a/src/include/optimizer/optimizer.h b/src/include/optimizer/optimizer.h
index 7be1e5906b..409005bae9 100644
--- a/src/include/optimizer/optimizer.h
+++ b/src/include/optimizer/optimizer.h
@@ -24,11 +24,6 @@
 
 #include "nodes/parsenodes.h"
 
-/* Test if an expression node represents a SRF call.  Beware multiple eval! */
-#define IS_SRF_CALL(node) \
-	((IsA(node, FuncExpr) && ((FuncExpr *) (node))->funcretset) || \
-	 (IsA(node, OpExpr) && ((OpExpr *) (node))->opretset))
-
 /*
  * We don't want to include nodes/pathnodes.h here, because non-planner
  * code should generally treat PlannerInfo as an opaque typedef.