AssertionError in MustCallInference::inferOwningField with @MustCallUnknown Fields

[iamsanjaymalakar]

Description:

The Checker Framework throws an AssertionError when attempting to infer the @Owning annotation for fields with a @MustCallUnknown annotation. This occurs during the processing of generic class fields when the MustCallInference method incorrectly handles fields marked as @MustCallUnknown, leading to a failure in the assertion due to both @CalledMethods({}) and mustCallValues being empty.

Steps to Reproduce:

Create a Java file with the following content:

class Generic<T> {
  public T data;

  public Generic(T data) {
    this.data = data;
  }
}

public class GenericClassFieldCrash {
  private void onPacket(Generic foo) {
    String.format("socket received: data '%s'", foo.data);
  }
}

Run the Checker Framework (version 3.43.0-SNAPSHOT) on this file with the Resource Leak Checker enabled. Or run the resource leak inference test suite.

./gradlew AinferResourceLeakAjavaTest

Expected Behavior:

The Checker Framework should either correctly infer the @Owning annotation for fields marked as @MustCallUnknown or conservatively avoid inferring an @Owning annotation to prevent an AssertionError.

Actual Behavior:

The Checker Framework crashes with an AssertionError, indicating a failure to handle @MustCallUnknown fields correctly during the inference process.

Stack Trace:

error: SourceChecker.typeProcess: unexpected Throwable (AssertionError) while processing /Users/sanjay/checker-framework/checker/tests/ainfer-resourceleak/non-annotated/GenericClassFieldCrash.java; message: Must-call obligation of owning field data is empty.
  ; The Checker Framework crashed.  Please report the crash.  Version: Checker Framework 3.43.0-SNAPSHOT, branch master, 2024-03-04, commit 7743e5d, dirty=true. 
  Compilation unit: /Users/sanjay/checker-framework/checker/tests/ainfer-resourceleak/non-annotated/GenericClassFieldCrash.java
  Last visited tree at line 10 column 1:
  public class GenericClassFieldCrash {
  Exception: java.lang.AssertionError: Must-call obligation of owning field data is empty.; java.lang.AssertionError: Must-call obligation of owning field data is empty.
  	at org.checkerframework.checker.resourceleak.MustCallInference.inferOwningField(MustCallInference.java:402)
  	at org.checkerframework.checker.resourceleak.MustCallInference.inferOwningForParamOrField(MustCallInference.java:716)
  	at org.checkerframework.checker.resourceleak.MustCallInference.inferOwningForRecieverOrFormalParamPassedToCall(MustCallInference.java:693)
  	at org.checkerframework.checker.resourceleak.MustCallInference.inferOwningFromInvocation(MustCallInference.java:796)
  	at org.checkerframework.checker.resourceleak.MustCallInference.runInference(MustCallInference.java:255)
  	at org.checkerframework.checker.resourceleak.MustCallInference.runMustCallInference(MustCallInference.java:213)
  	......
	  at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
	  at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)

Analysis:

The method MustCallInference::inferOwningField incorrectly assumes that a field with a @MustCallUnknown annotation can have a non-empty must-call obligation. This leads to an assertion failure when both the called methods annotation (cmAnno) and the must-call values (mustCallValues) are empty, despite passing the must-call consistency check.

Proposed Solution:

Modify the ResourceLeakAnnotatedTypeFactory::isFieldWithNonemptyMustCallValue method to return false for fields whose MC type is @MustCallUnknown. This change will conservatively avoid inferring an @Owning annotation. Thus, avoiding incorrectly inferring an @Owning annotation for fields marked as @MustCallUnknown, addressing the assertion error.

Environment:

Checker Framework Version: 3.43.0-SNAPSHOT
Java Version: JDK 8