Programs compile in g ++, but exit with linker errors in gcc

Question

I am testing the solution on the issue of specialized template classes .

This compiled code is excellent in g ++, but it causes linker errors when compiling with gcc. What is the cause of these errors?

$ g++ traits2.cpp
$ gcc traits2.cpp
/tmp/ccI7CNCY.o: In function `__static_initialization_and_destruction_0(int, int)':
traits2.cpp:(.text+0x36): undefined reference to `std::ios_base::Init::Init()'
traits2.cpp:(.text+0x3b): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccI7CNCY.o:(.eh_frame+0x11): undefined reference to `__gxx_personality_v0'
collect2: ld returned 1 exit status

The traits2.ccp file contains the above solution with the emtpy main () function:

#include <iostream>

using namespace std;

// A default Traits class has no information
template<class T> struct Traits
{
};

// A convenient way to get the Traits of the type of a given value without
// having to explicitly write out the type
template<typename T> Traits<T> GetTraits(const T&)
{
    return Traits<T>();
}

template <int major, int minor> struct A 
{ 
    void f() 
    { 
        cout << major << endl; 
    }   
};

// Specialisation of the traits for any A<int, int>
template<int N1, int N2> struct Traits<A<N1, N2> >
{
    enum { major = N1, minor = N2 };
};

template <> struct A<4,0> 
{       
    void f() 
    { 
        cout << "Specialized:" << GetTraits(*this).major << endl; 
    }   
};

int main(int argc, char * argv[] )
{
    /*
    A<4,0> p;
    A<1,2> p2;
    p.f();
    p2.f();
    */
    return 1;
}

Answer 1

When compiling with gcc, C ++ libraries are not connected by default. Always generate C ++ code with g ++.

Answer 2

If you want to see the difference for yourself, try both versions with the -v flag

$ g++ -v traits2.cpp
$ gcc -v traits2.cpp

, .

Answer 3

Your code is C ++, so it must be compiled with g ++, the C ++ compiler, not gcc, the C compiler.