https://issues.dlang.org/show_bug.cgi?id=19817

          Issue ID: 19817
           Summary: Incorrect common type for const enum and mutable enum
                    when sized
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: major
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: eyal@weka.io

This works:
{
    enum E1 { A }
    E1 a;
    const(E1) b;
    static assert(is(typeof(a) == E1));
    static assert(is(typeof(b) == const(E1)));
    static assert(is(typeof(1 ? a : b) == const(E1)));
}

but this doesn't, as unify of const(E2) and E2 is not E2, but int:
{
    enum E2 : ubyte { A }
    E2 a;
    const(E2) b;
    static assert(is(typeof(a) == E2));
    static assert(is(typeof(b) == const(E2)));
    static assert(is(typeof(1 ? a : b) == const(E2))); // Error: static assert:
 `is(int == const(E2))` is false
}

--