test/tools/javac/defaultMethods/Neg07.java

/* @test /nodynamiccopyright/
 * @bug 7192246
 * @summary check that default overrides are properly type-checked
 * @compile/fail/ref=Neg07.out -XDrawDiagnostics Neg07.java
 */

class Neg07 {
    interface I {
        default int m() { return 1; }
    }

    static class C1 {
        public void m() { } //incompatible return
    }

    static class C2 extends C1 implements I { }

    static class C3 implements I {
        public void m() { } //incompatible return
    }
}