Mismatched nullability of type parameters when using Nullable with AtomicReferenceFieldUpdater

[violetagg]

I have a problem when I try to use @Nullable and AtomicReferenceFieldUpdater , this snippet:

class A {
	static final AtomicReferenceFieldUpdater<A, @Nullable Object> RESULT_UPDATER =
			AtomicReferenceFieldUpdater.newUpdater(A.class, Object.class, "result");
	volatile @Nullable Object result;

	A() {
		System.out.println("Set operation result " + RESULT_UPDATER.compareAndSet(this, null, new Object()));
	}
}

Gives the following error:

/nullaway-mismatched-nullability/src/main/java/org/example/A.java:8: error: [NullAway] Cannot assign from type AtomicReferenceFieldUpdater<A, Object> to type AtomicReferenceFieldUpdater<A, @Nullable Object> due to mismatched nullability of type parameters
	static final AtomicReferenceFieldUpdater<A, @Nullable Object> RESULT_UPDATER =
	                                                              ^

The repository with the reproducible example can be found here https://github.com/violetagg/nullaway-mismatched-nullability

[msridhar]

Thanks for the report! This is #1075, and we should fix this particular case in #1131, which we're hoping to land soon! In the meantime, you can write AtomicReferenceFieldUpdater.<A, @Nullable Object>newUpdater(...) as a temporary workaround.

Will close as a duplicate for now

[violetagg]

Thanks

[msridhar]

Inference works for this case now (see #1289) but we need better JDK models to get this working as-is. That's issue #950. I'll make this a sub-issue of that one so we make sure we test this is working once we have better JDK models imported.

[chemicL]

Hi! I just wanted to add a data point reflecting the importance of addressing this. In reactor-core we currently have 137 suppressions related to this problem. I am hopeful that the annotated JDK models can improve this. Thank you for the research and hard work put into addressing all the corner cases :)

[msridhar]

Wow, thanks for the info @chemicL! When I get some cycles I'll try to work on a targeted fix for this issue.