@EnsuresNonNullIf doesn't seem to work as expected when used in a superclass

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#2,013 opened on Jun 5, 2018 8 comments 1 reaction 0 assignees View on GitHub

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Dominant language: Java
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Description

Here's a live example:

http://eisop.uwaterloo.ca/live#mode=display&code=import+org.checkerframework.checker.nullness.qual.Nullable%3B%0Aimport+org.checkerframework.checker.nullness.qual.EnsuresNonNullIf%3B%0Aimport+org.checkerframework.dataflow.qual.Pure%3B%0A%0Aabstract+class+Animal+%7B%0A++%40Pure%0A++%40EnsuresNonNullIf(expression%3D%22asDog()%22,+result%3Dtrue)%0A++boolean+isDog()+%7B%0A++++return+false%3B%0A++%7D%0A++%0A++%40Nullable%0A++Dog+asDog()+%7B%0A++++return+null%3B%0A++%7D%0A%7D%0A%0Aclass+Dog+extends+Animal+%7B%0A++++%40Override%0A++++boolean+isDog()+%7B%0A++++++++return+true%3B%0A++++%7D%0A++++%0A++++%40Override%0A++++Dog+asDog()+%7B%0A++++++++return+this%3B%0A++++%7D%0A%7D&typeSystem=nullness

As you can see, this fails to validate and I'm unsure why.

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Research direction

Reproduce the Java example from the live link with the nullness type system, then trace how @EnsuresNonNullIf is handled for methods declared in a superclass and overridden in Dog. Done means the example validates as expected, with regression coverage for this inheritance case if the project’s existing tests provide an appropriate entry point.

Written by the indexing model from the issue text.

Assessment

Tech stack: java
Domain: devtools
Issue type: Bug
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Stale
Clarity: Mostly clear
Newbie friendliness: 35/100