If you need to provide your own custom translation of some type (for example, because you need to wrap one of its fields in an UnsafeCell), you can explicitly blocklist generation of its definition. Uses of the blocklisted type will still appear in other types' definitions. (If you don't want the type to appear in the bindings at all, make it opaque instead of blocklisting it.)
Blocklisted types are pessimistically assumed not to be able to derive any traits, which can transitively affect other types' ability to derive traits or not.
--blocklist-type <type>/// <div rustbindgen hide></div> class Foo { // ... };