That example will scare people away for 2 reasons. Besides the one presented, there is the awkward ergometric of having to specify the instance TWICE in  memfunc_to_func and  invoke_func_as_memfunc which then leads to the presented problem.

At compile time for KNOWN instance `a` you can call both Base::Go and Derived1::Go.

At compile time for KNOWN instance `b` you can call both Base::Go and Derived2::Go.

function_ref allows you to do these same 4 tasks and you don't have to make Base, Derived1 or Derived2 virtual at all.

function_ref, Dyno and the others are really a better form of polymorphism that you ?should? defer to 85/90/95/99% of the time.

https://youtube.com/clip/Ugkxo9iqdK7DOY8JCS6hvw9x-P5FqO849zSQ?si=J85Eh-aLJdpgBOqX

On Fri, Jan 5, 2024 at 10:54 AM Frederick Virchanza Gotham via Std-Proposals <std-proposals@lists.isocpp.org> wrote:

On Friday, January 5, 2024, Frederick Virchanza Gotham wrote:

The above code will invoke the 'Derived2::Go' member function on an object of type 'Derived1'. 

Typographical error:

     Swap 'Derived2' with 'Derived1'. 

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