+/* We're using the "is_of_type_list" to conditionally defer to the
+ * notmuch_mset_messages_t implementation of notmuch_messages_t in
+ * query.cc. It's ugly that that's over in query.cc, and it's ugly
+ * that we're not using a union here. Both of those uglies are due to
+ * C++:
+ *
+ * 1. I didn't want to force a C++ header file onto
+ * notmuch-private.h and suddenly subject all our code to a
+ * C++ compiler and its rules.
+ *
+ * 2. C++ won't allow me to put C++ objects, (with non-trivial
+ * constructors) into a union anyway. Even though I'd
+ * carefully control object construction with placement new
+ * anyway. *sigh*
+ */