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  1. JDK
  2. JDK-8029240

Default methods not always visible under -source 7

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    • Subcomponent:
    • Resolved In Build:
      b01
    • Verification:
      Verified

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        Description

        Consider an interface available to pre-8 programs that changes an abstract method to a default method, and adds another default method:

        interface I { void m(); }
        // becomes
        interface I {
          default void m() {}
          default void n() {}
        }

        (The method n is just for illustration -- there's no way to tell the difference between an old method that was converted to a default method and a fresh default method.)

        Also consider three subtypes of I:
        interface J extends I {}
        abstract class A implements I {}
        class B implements I {}

        javac should be able to cleanly handle the following scenarios:

        1) Legacy implementations of I, J, A, and B still compile under -source 7 and don't need to implement I.n

        class C1 implements I { @Override public void m() {} }
        // Expected: success
        // Actual: success

        class C2 implements J { @Override public void m() {} }
        // Expected: success
        // Actual: success

        class C3 extends A { @Override public void m() {} }
        // Expected: success
        // Actual: success

        class C4 extends B { @Override public void m() {} }
        // Expected: success
        // Actual: success

        2) Legacy invocations of m via I, J, A, and B still compile under -source 7

        class Test {
          public static void test(I i, J j, A a, B b) {
            i.m();
            j.m();
            a.m();
            b.m();
          }
        }
        // Expected: success
        // Actual: error -- B does not have an m method

        3) Super invocations of m via A and B compile under -source 7:

        class SubA extends A {
          public void test() { super.m(); }
        }
        // Expected: success
        // Actual: success

        class SubB extends B {
          public void test() { super.m(); }
        }
        // Expected: success
        // Actual: error -- B does not have an m method

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                Assignee:
                vromero Vicente Arturo Romero Zaldivar
                Reporter:
                dlsmith Dan Smith
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                  Updated:
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