exception, -fvisibility=hidden and shared object

#include <iostream>
#include <stdexcept>

int my_object();

int main()
{
  try{
  my_object();
  }
  catch(std::exception & e)
  {
    std::cout << e.what() << std::endl;
  }
  return 0;
}

Version 1

#include <stdexcept>

int __attribute__ ((visibility("default"))) my_object()
{
  throw std::runtime_error("my_object throw");
}

compile it with

g++ -shared -o libshared.so shared1.cpp -fvisibility=hidden

and

g++ -o main main.cpp -lshared -L. -fvisibility=hidden

in this case: WORKS
The first version shows that throw a std::exception and capture it, works.
In fact GCC uses std::exception RTTI symbols stored in GLIBC and does not need to export it again.

Version 2

#include <stdexcept>

class my_exception : public std::exception {
  public:
  virtual ~my_exception() throw() { }
  virtual const char*
          what() const throw() { return "my_exception"; }
};

int __attribute__ ((visibility("default"))) my_object()
{
  throw my_exception();
}

in this case: WORKS.
my_exception's RTTI is not exported, however the parent one continues to be stored in GLIBC and, in such way, available.

Version 3

my_hidden_exception.h

class my_exception {
  public:
  virtual ~my_exception() throw() { }
  virtual const char*
          what() const throw() { return "my_exception"; }
};

main3.cpp:

#include <iostream>
#include "my_hidden_exception.h"

int my_object();

int main()
{
  try{
  my_object();
  }
  catch(my_exception & e)
  {
    std::cout << e.what() << std::endl;
  }
  return 0;
}

shared3.cpp:

#include "my_hidden_exception.h"

int __attribute__ ((visibility("default"))) my_object()
{
  throw my_exception();
}

In this case it does NOT WORK!

# ./main
terminate called after throwing an instance of 'my_exception'
Abort

(main)   RTTI address: 0x08048b4e
(shared) RTTI address: 0xb77b7a0c

Version 4

class __attribute__ ((visibility("default")))  my_exception {
  public:
  virtual ~my_exception() throw() { }
  virtual const char*
          what() const throw() { return "my_exception"; }
};

#include <iostream>
#include "my_exception.h"

int my_object();

int main()
{
  try{
  my_object();
  }
  catch(my_exception & e)
  {
    std::cout << e.what() << std::endl;
  }
  return 0;
}

#include "my_exception.h"

int __attribute__ ((visibility("default"))) my_object()
{
  throw my_exception();
}

See Also