dmd/compiler/test/fail_compilation/fail100.d

/*
TEST_OUTPUT:
---
fail_compilation/fail100.d(24): Error: return value `f` of type `Class[]` does not match return type `I[]`, and cannot be implicitly converted
---
*/

// https://issues.dlang.org/show_bug.cgi?id=85
// Array of classes doesn't function as array of interfaces
interface I
{
    I[] foo();
    uint x();
}

class Class : I
{
    I[] foo()
    {
        // changing this to I[] f = new Class[1] fixes the bug
        Class[] f = new Class[1];
        //I[] f = new Class[1];
        f[0] = new Class;
        return f;
    }

    uint x()
    {
        return 0;
    }
}

void main()
{
    Class c = new Class();
    assert(c.x == 0);
    assert(c.foo[0].x == 0);
}