Name: ngR10089 Date: 01/28/2004


 
The latest spec of "Adding Generics to the Java Programming Language: Public
Draft Specification, Version 2.0", 5.4 reads:

    "A value of type S can be cast to a parameterized type T if one of the
     following two conditions holds:

      o T is a subtype of S, and there are no other subtypes of S with the
        same erasure (see Section 6.1) as T.
      o . . ."


However javac (jdk1.5.0-b35) successfully compiles test below.

> javac -d . -source 1.5 *.java
Note: test.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
> java -Xfuture p.test
++ 1
Test
++ 2
Test
>
--------------- test.java-------------
package p;
import java.io.PrintStream;

class cl_b<A> {
    A value;
}
class cl_a<A> extends cl_b<A> {
    cl_a(A value) {
        this.value = value;
    }
}

public class test {
    public static void main(String argv[]) {
        System.exit(run(argv, System.out) + 95/*STATUS_TEMP*/);
    }
    public static int run(String argv[],PrintStream out) {
        boolean result = true;
        cl_b y = new cl_a<String>("Test");
        cl_a<Integer> z1;
        cl_a<String> z;
        try {
            z = (cl_a<String>)y;
            out.println("++ 1");
            out.println(z.value);
        } catch (Throwable e) {
            out.println("==1 "+e);
        }
        try {
            z1 = (cl_a<Integer>)y;
            out.println("++ 2");
            out.println(z1.value);
        } catch (Throwable e) {
            out.println("==2 "+e);
        }
        return 0/*STATUS_PASSED*/;
    }
}
---------------------------------------

New JCK tests
lang/EXPR/expr674/expr67402/expr67402.html
fails due to this bug.



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