cereal multiple definition example. compile with: CEREAL_INCLUDE=/path/to/cereal/include make

a.hpp

#ifndef AG
#define AG

struct A
{
    virtual ~A() {}
    virtual void hello()=0;
};

#endif

b.cpp

#include "b.hpp"
#include <iostream>

// FIXME: this is needed after the patch in only one TU
// CEREAL_BIND_TO_ARCHIVES(B)

B::B() {}

void B::hello()
{
    std::cout << "B\n";
}

b.hpp

#ifndef BG
#define BG

#include <cereal/archives/binary.hpp>
#include <cereal/types/polymorphic.hpp>
#include "a.hpp"

struct B : A
{
    B();

    void hello();

    template <typename Archive>
    void serialize(Archive & ar)
    {
    }
};

CEREAL_REGISTER_TYPE(B)

#endif

c.cpp

#include "c.hpp"
#include <iostream>

// FIXME: this is needed after the patch in only one TU
// CEREAL_BIND_TO_ARCHIVES(C)

C::C() {}

void C::hello()
{
    std::cout << "C\n";
}

c.hpp

#ifndef CG
#define CG

#include <cereal/archives/binary.hpp>
#include <cereal/types/polymorphic.hpp>
#include "a.hpp"

struct C : A
{
    C();

    void hello();

    template <typename Archive>
    void serialize(Archive & ar)
    {
    }
};

CEREAL_REGISTER_TYPE(C)

#endif

fix.patch

diff --git a/include/cereal/types/polymorphic.hpp b/include/cereal/types/polymorphic.hpp
index 6e966d4..28745df 100644
--- a/include/cereal/types/polymorphic.hpp
+++ b/include/cereal/types/polymorphic.hpp
@@ -62,7 +62,6 @@
     static constexpr char const * name() { return #T; }; \
   };                                                     \
   } } /* end namespaces */                               \
-  CEREAL_BIND_TO_ARCHIVES(T);
 
 //! Registers a polymorphic type with cereal, giving it a
 //! user defined name
@@ -77,7 +76,6 @@
   struct binding_name<T>                                      \
   { static constexpr char const * name() { return Name; }; }; \
   } } /* end namespaces */                                    \
-  CEREAL_BIND_TO_ARCHIVES(T);
 
 namespace cereal
 {

main.cpp

#include "b.hpp"
#include "c.hpp"

#include <memory>
#include <cereal/cereal.hpp>

int main()
{
    std::stringstream stream;
    {
        cereal::BinaryOutputArchive oarchive(stream);
        std::shared_ptr<A> b(new B);
        std::shared_ptr<A> c(new C);

        oarchive(b, c);
    }
    {
        cereal::BinaryInputArchive iarchive(stream);
        std::shared_ptr<A> b;
        std::shared_ptr<A> c;
        
        iarchive(b, c);
        b->hello();
        c->hello();
    }
}

Makefile

all: main

b.o: b.cpp b.hpp a.hpp
	g++ -std=c++11 -c b.cpp -I$(CEREAL_INCLUDE)

c.o: c.cpp c.hpp a.hpp
	g++ -std=c++11 -c c.cpp -I$(CEREAL_INCLUDE)

main: main.cpp b.o c.o
	g++ -std=c++11 -o test main.cpp b.o c.o -I$(CEREAL_INCLUDE)