+ threads running in it.
+
+ Inferiors are intrusively refcounted objects. Unlike thread
+ objects, being the user-selected inferior is considered a strong
+ reference and is thus accounted for in the inferior object's
+ refcount (see set_current_inferior). When GDB needs to remember
+ the selected inferior to later restore it, GDB temporarily bumps
+ the inferior object's refcount, to prevent something deleting the
+ inferior object before reverting back (e.g., due to a
+ "remove-inferiors" command (see
+ make_cleanup_restore_current_thread). All other inferior
+ references are considered weak references. Inferiors are always
+ listed exactly once in the inferior list, so placing an inferior in
+ the inferior list is an implicit, not counted strong reference. */
+
+class inferior : public refcounted_object