what operator(s) should I overload to prevent this?

[drug via Digitalmars-d-learn]

I refactored `MyStructure` added own implementation of malloced array 
based on pureRealloc/pureFree instead of dynamic array I used before and 
now I have error:
Error: cannot implicitly convert expression get(msg.getData()) of type 
const(MyStructure) to MyStructure.

What operators should I overload to let this conversion? I've tryed 
opCast and it fails in other call sites, also I've tried opAssign - it 
didn't works, what worked is wrapping in ctor - MyStruct(const_var). But 
using ctor is not convenient.