test/langtools/tools/javac/generics/PermuteBound.java

/*
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 *
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 */

/*
 * @test
 * @bug 4698375
 * @summary generics: subtyping problem when type parameters permuted
 * @author gafter
 *
 * @compile  PermuteBound.java
 */

package PermuteBound;

class C<X, Y> {}

class D<X, Y> extends C<X, Y>
{
    void f(C<X, Y> c)
    {
        D<X, Y> d = (D<X, Y>) c;// OK because D extends C
    }

    void g(C<Y, X> c)// parameters X and Y are now permuted
    {
        D<Y, X> d = (D<Y, X>) c;// should also be OK but is not !?
        //                    ^
        // inconvertible types
        // found :    C<Y,X>
        // required : D<Y,X>
    }
    /*
    void gWorkAround(C<Y, X> c)// but generates unchecked warning
    {
        D<Y, X> d = (D) ((C) c);
    }
    */
}