Description Vladimir Tsichevski 2015-06-25 16:07:00 EDT

Created attachment 254724 [details]
The tiny complete eclipse project that demonstrates the bug

I have two classes: y.A and x.B:

------------------------------------------------
package y;

public class A {
  private String f = "";

  public void setF(String v) {
    f = v;
  }

   public String getF() {
    return f;
  }
}
------------------------------------------------
package x;

import java.util.concurrent.Callable;

public class B {

  public static void dummy(final A p) throws Exception {
    dummy1(() -> {
      p.setF("a");
      return "b";
    });
    p.setF("c");
  }

  public static <T> void dummy1(Callable<T> callable) throws Exception {
    callable.call();
  }
}
------------------------------------------------

1. I have Java compiler null analysis On.
2. I set the NonNullByDefault behaviour on in all package-info.java
3. The compiler complains:
Null type safety (type annotations): The expression of type 'String' needs unchecked conversion to conform to '@NonNull String'

for the 'v' parameter of void A.setF(String v).

This happens when all the following conditions are met:

1. Every time after I have 'project clean' called. If I touch the A.java in the editor, the problem disappears.
2. I refer the 'setF' in a lambda expression. If I change the lambda to an anonymous class, the problem disappears.
3. If I have no statements with a call to 'setF' before is is referred in the lambda. For example, if I move the 'p.setF("c");' statement to the beginning of the 'dummy' method, the problem disappears.
4. If the package for the A class ('y' in my example) is alphabetically after the package of the B class ('x' in my example).

The whole project is appended to this report.

I use eclipse-rcp-mars-R-linux-gtk-x86_64