How to write a member function alias?

In modern C++ is it possible to write a member function alias with a syntax different from this:

class C {
   int f(int a) { return ++a; }
   inline int g(int a) { return f(a); }
};

I tried in a few ways, none of which work:

class C {
   int f(int a) { return ++a; }
   const auto g1 = f;  // error: 'auto' not allowed in non-static class member
   auto& g2 = f;       // error: 'auto' not allowed in non-static class member
   using g3 = f;       // error: unknown type name 'f'
};

Please, do not suggest to use the preprocessor...

Why do I need this? Because:

• I have existing code which I cannot modify that uses the old member function, and new code that must use the new.
• I would like to avoid the extra call (even if it can be optimized away).

P.S.: errors generated by clang 20.1.0

As of today (C++23) there's no solution to have transparent aliases of function or member functions. There is a proposal that adds exactly what you need:

P0945: Generalizing alias declarations

But, as far as I know, there has been no recent activity on this proposal.

The closest you can do today is using a forced inline function:

class C {
   int f(int a) { return ++a; }

   [[clang::always_inline]] // if you use clang
   [[gnu::always_inline]]   // if you use gcc or clang
   __forceinline            // if you use msvc
   int g(int a) { return f(a); }
};