Dagger generates map size check that cannot be optimized by R8

When inspecting the optimized and decompiled code of my app for a completely different reason, I noticed this weird code (obfuscation turned off for better readability):

LinkedHashMap newLinkedHashMapWithExpectedSize = DaggerCollections.newLinkedHashMapWithExpectedSize(27);
newLinkedHashMapWithExpectedSize.put(BaseActivity.class, daggerAppComponent.baseActivitySubcomponentFactoryProvider);
...
newLinkedHashMapWithExpectedSize.put(NotificationClearBroadcastReceiver.class, daggerAppComponent.notificationClearBroadcastReceiverSubcomponentFactoryProvider);
if (newLinkedHashMapWithExpectedSize.size() != 0) {
    map = Collections.unmodifiableMap(newLinkedHashMapWithExpectedSize);
} else {
    map = Collections.emptyMap();
}

The check for size() != 0 is unnecessary as the map obviously is not empty. The generated code by dagger looks like this

MapBuilder.<Class<?>, Provider<AndroidInjector.Factory<?>>>newMapBuilder(27).put(BaseActivity.class, (Provider) baseActivitySubcomponentFactoryProvider). ... .build()

Seems like R8 is able to strip the MapBuilder, but not the size check. I think an easy fix could be checking for the size that has been passed to the constructor of the builder instead of calling size() (R8 will be able to optimize that), an even better one to not generate that size check at all when the size is known at compile time (R8 doesn’t even need to optimize it).

[connyduck]

Yes its Daggers MapBuilder, I should have been more clear about that.

@JakeWharton I would appreciate it if you do a feature request

[JakeWharton]

Thanks! Since it’s a one-liner I won’t bother with a PR since it’ll actually make things harder.

@connyduck do you want to pursue the R8 feature request? If not I am happy to.