Orthography fixes for new castNode() macro.

Clean up hastily-composed comment.  Normalize whitespace.

Erik Rijkers and myself

src/include/nodes/nodes.h

@@ -559,23 +559,23 @@ extern PGDLLIMPORT Node *newNodeMacroHolder;
 #define IsA(nodeptr,_type_)		(nodeTag(nodeptr) == T_##_type_)
 
 /*
- * castNode(type, ptr) casts ptr to type and, if cassert is enabled, verifies
+ * castNode(type, ptr) casts ptr to "type *", and if assertions are enabled,
- * that the the c actually has the appropriate type (using it's nodeTag()).
+ * verifies that the node has the appropriate type (using its nodeTag()).
  *
  * Use an inline function when assertions are enabled, to avoid multiple
  * evaluations of the ptr argument (which could e.g. be a function call).
  */
 #ifdef USE_ASSERT_CHECKING
 static inline Node *
-castNodeImpl(enum NodeTag type, void *ptr)
+castNodeImpl(NodeTag type, void *ptr)
 {
 	Assert(ptr == NULL || nodeTag(ptr) == type);
-	return ptr;
+	return (Node *) ptr;
 }
 #define castNode(_type_, nodeptr) ((_type_ *) castNodeImpl(T_##_type_, nodeptr))
 #else
 #define castNode(_type_, nodeptr) ((_type_ *) (nodeptr))
-#endif
+#endif   /* USE_ASSERT_CHECKING */
 
 
 /* ----------------------------------------------------------------