1 /*

     2  * @test /nodynamiccopyright/

     3  * @bug 8231827

     4  * @summary Ensure that in type test patterns, the predicate is not trivially provable false.

     5  * @compile/fail/ref=ImpossibleTypeTest.out -XDrawDiagnostics --enable-preview -source ${jdk.version} ImpossibleTypeTest.java

     6  */

     7 public class ImpossibleTypeTest {

     8 

     9     public static void main(String[] args) {

    10 

    11         int in = 42;

    12         Integer i = 42;

    13 

    14         if (i instanceof String s ) {

    15             System.out.println("Broken");

    16         }

    17         if (i instanceof Undefined u ) {

    18             System.out.println("Broken");

    19         }

    20     }

    21 }