#[lang = "phantom_data"]
//~^ ERROR `phantom_data` language item must be applied to a struct with 1 generic argument
struct MyPhantomData<T, U>;
-//~^ ERROR parameter `T` is never used
-//~| ERROR parameter `U` is never used
#[lang = "owned_box"]
//~^ ERROR `owned_box` language item must be applied to a struct with at least 1 generic argument