C++: how to export only RTTI, not methods symbols ?

[Benoit Jacob]

Hi,

I would like to know the least intrusive way in which I can modify a
C++ class like this:

class Foo {
  void bar1();
  void bar2();
  void bar3();
};

to have its RTTI always visibility=default so that users can use
typeid(Foo), while having all its methods visibility=hidden?

By "least intrusive" I mostly mean that I would like not to have to
manually add a visibility attribute for each of its methods.

Cheers,
Benoit