typetools / typetools/checker-framework

failed to report type argument that does not satisfy upper bound

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#6,868 0 comments 0 reactions 1 assignee View on GitHub

@smillst is already working on this.

Since Oct 23, 2024.

False Negative (missing warning or unsoundness)
Dominant language
Java
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Description

Command
javac -J--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
  -J--add-exports=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED \
  -J--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
  -J--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED \
  -J--add-exports=jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED \
  -J--add-exports=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED \
  -J--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
  -J--add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED \
  -J--add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED \
-processor org.checkerframework.checker.nullness.NullnessChecker \
-cp ~/projects/checker-framework/checker/dist/checker.jar -Aignorejdkastub Test.java
File
import org.checkerframework.checker.nullness.qual.*;


class A<T extends Number> {}

public class Test {
  public static <T> T bottom() { throw new RuntimeException(); }

  public static A<? extends Number> test() {
      return (true) ?
           Test.<A<@Nullable Number>>bottom() : 
           Test.<A<@Nullable Number>>bottom(); 
      
  }
}
Actual behavior

The code passes the checks although @Nullable Integer is not a valid subtype of T extends Number.

I attempted to create a reproducible test case that triggers a NullPointerException due to this mismatch, but I was unable to do so. This suggests that, in practice, the issue might not cause immediate problems.

However, I decided to report this issue in case the underlying root cause could manifest itself through different symptoms in other scenarios.

Expected behavior

The code should have been rejected as @Nullable Integer is not a valid subtype of T extends Number.

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Assessment

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