IssueTracker

Component used: Navigation

Version used: 2.8.5

The NavDestination.fillInLabel method attempts to fill in the label of the NavDestination with arguments. However, it does this by (in every case but NavType.ReferenceType) by just calling args[argName].toString() - e.g., just directly calling toString() on the object in the SavedState bundle.

While this approach works for simple types, a custom NavType might not store their class directly in the Bundle - for example, if using the @Serializable support, it would be stored as a Bundle, which means the toString() is unlikely to actually be what is needed.

Instead, fillInLabel should take into account the NavType and use its get method to give the NavType control over exactly the object that is synthesized from the arguments. That way, developers could implement a custom toString() implementation on their object to control how it is displayed in the label.