Lub annotations on anonymous constructors

checker/tests/mustcall/FunctionalInterfaces.java

@@ -0,0 +1,52 @@
+// Test that the correct type is assigned to instantiations of functional
+// interfaces.
+// https://github.com/typetools/checker-framework/issues/6823
+
+import java.io.Closeable;
+import org.checkerframework.checker.mustcall.qual.*;
+
+public abstract class FunctionalInterfaces {
+
+  @FunctionalInterface
+  public interface Actor extends Closeable {
+    void act();
+
+    @Override
+    default void close() {}
+  }
+
+  public static class ActorImpl implements Actor {
+    @Override
+    public void act() {}
+  }
+
+  public abstract void run(@MustCall({}) Actor a);
+
+  public static void method() {}
+
+  public void normalConstruction() {
+
+    // :: error: (assignment)
+    @MustCall({}) Actor a = new ActorImpl();
+  }
+
+  public void inlineClass() {
+
+    class ActorImplInline implements Actor {
+      @Override
+      public void act() {}
+    }
+
+    // :: error: (assignment)
+    @MustCall({}) Actor a = new ActorImplInline();
+  }
+
+  public void anonymousClass() {
+
+    // :: error: (assignment)
+    @MustCall({}) Actor a =
+        new Actor() {
+          public void act() {}
+        };
+  }
+}

framework/src/main/java/org/checkerframework/framework/type/AnnotatedTypeFactory.java

@@ -2826,7 +2826,13 @@ protected ParameterizedExecutableType constructorFromUse(
         p.addAll(1, superCon.getParameterTypes());
         con.setParameterTypes(p);
       }
-      con.getReturnType().replaceAnnotations(superCon.getReturnType().getPrimaryAnnotations());
+      Set<? extends AnnotationMirror> lub =
+          qualHierarchy.leastUpperBoundsShallow(
+              type.getPrimaryAnnotations(),
+              type.getUnderlyingType(),
+              superCon.getReturnType().getPrimaryAnnotations(),
+              superCon.getReturnType().getUnderlyingType());
+      con.getReturnType().replaceAnnotations(lub);
     } else {
       con = AnnotatedTypes.asMemberOf(types, this, type, ctor, con);
     }