immutable class can't override opEquals, workaround?

[SimonN via Digitalmars-d-learn]

Hi,

     immutable class A {
         int i;
         this(int arg) { i = arg; }
         override bool opEquals(Object rhsObj)
         {
             auto rhs = cast (immutable(A)) rhsObj;
             return rhs && i == rhs.i;
         }
     }

Error by dmd 2.070:

     ./immutclass.d(4): Error: function immutclass.A.opEquals
     does not override any function, did you mean to override
     'object.Object.opEquals'?

My understandings:

1.  immutable class A means: All methods have immutable tacked
     on them implicitly.
2.  Object.opEquals doesn't have immutable tacked on it. If I
     want to override Object.opEquals, I should override without
     'immutable'.
3.  Overriding opEquals and toHash are necessary to make A
     behave properly as AA key type. This is incompatible with
     (2) in an immutable class.
4.  I found this thread:
         How to turn an inout(Object) into a string
         
http://forum.dlang.org/thread/dcobmtogyrmnaqnqyvbz@forum.dlang.org
     that I interpret as: The need for the currently-impossible
     override is acknowledged, but the implementation would bring
     significant changes to the language, therefore the solution
     is postponed. The above thread was from mid-2015, but I guess
     it's still relevant.

My workaround is: Make class _A private, and declare every method
immutable, except for what Object decrees to be mutable/const/...
Then make a public alias A = immutable(_A).

Is there something better than this?

Has there been any new development on Object method removal?
Jonathan M Davis has been pushing this hard 2 years ago, I'd
love to see the efforts make it into the language. :-)

-- Simon