Conflicting `@Inject`

In general, Dagger does not allow a conflicting binding for the same key in a subcomponent and an ancestor component. There are two exceptions:

• A subcomponent can replace an absent @BindsOptionalOf binding with an explicit binding.
• A subcomponent can add entries or elements to a multibinding.

It was never supposed to be possible for a subcomponent to have an explicit binding for a class if its @Inject binding was used in an ancestor component. However, that validation was mistakenly never implemented.

If an explicit binding in a subcomponent conflicts with an @Inject binding in an ancestor component, Dagger now reports a warning. To make those into errors, pass -Adagger.explicitBindingConflictsWithInject=ERROR to javac.

You have a few options to fix these conflicts:

1. Decide whether you really need both the @Inject binding and the explicit binding. If you need only the @Inject binding, you can delete the explicit one. If you need only the explicit one, you can move that into a module installed in the ancestor component, where it will replace the @Inject binding.

2. If you need both, then one or the other must be qualified. If one of the bindings is used from only a few places, qualify that one. To qualify the explicit binding, just add a qualifier. You cannot qualify an @Inject binding, so instead you must write an explicit qualified @Provides method in a module installed in the ancestor component, which calls the constructor explicitly. In either case, you have to add the qualifier to the dependency requests that you want to use the qualified binding.