Type refinement is very weak

[chaosflaws]

Running the nullness checker (checker -rpcessor nullness Test.java) on a very simple example:

public class Test {
    private void testFails1(@Nullable LocalDate x1, @Nullable LocalDate x2) {
        boolean eitherIsNull = x1 == null || x2 == null;
        if (eitherIsNull) return;
        delegate(x1, x2);
    }

    private void testFails2(@Nullable LocalDate x1, @Nullable LocalDate x2) {
        boolean firstIsNull = x1 == null;
        boolean secondIsNull = x2 == null;
        if (firstIsNull || secondIsNull) return;
        delegate(x1, x2);
    }

    private void testWorks(@Nullable LocalDate x1, @Nullable LocalDate x2) {
        if (x1 == null || x2 == null) return;
        delegate(x1, x2);
    }

    private void delegate(LocalDate x1, LocalDate x2) {
        // do something
    }
}

reports that in the two failing tests, x1 and x2 cannot be inferred to be non-null:

[...]\Test.java:11: error: [argument] incompatible argument for parameter x1 of delegate.
        delegate(x1, x2);
                 ^
  found   : @Initialized @Nullable LocalDate
  required: @Initialized @NonNull LocalDate

In the actual use case, eitherIsNull represents a more complex boolean expression that I would like to assign a name to. Currently, the checker framework prevents me from doing that.

[mernst]

Thank you for reporting the problem. I'm sorry you are having trouble. This issue is a duplicate of #406.

I just added a suggestion with a straightforward implementation strategy.

Issue #406 has "medium" priority, so we are unlikely to get to it very soon, unless more information/motivation comes to light about it. I'm sorry about that. However, if you would like to contribute a fix, we would be very grateful!