Default template arguments?, C++ (gcc)

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//g++  4.9.3
#include <iostream>
#include <type_traits>

/* contrived base and derived classes */
class BaseA
{
public:
  int getInt() const { return 21; };
};

class DerivedA : public BaseA {};

class BaseB
{
public:
  int getAnotherInt() const { return 33; };
};

class DerivedB : public BaseB {};

/* template functions that, seemingly, only differ in their
   default template arguments? */
template< class T,
          typename std::enable_if<std::is_base_of<BaseA, T>::value>::type* = nullptr >
int onlyForDerivedObjects(const T& obj)
{
  return 2*obj.getInt();
}

template< class T,
          typename std::enable_if<std::is_base_of<BaseB, T>::value>::type* = nullptr >
int onlyForDerivedObjects(const T& obj)
{
  return 3*obj.getAnotherInt();
}

/* template argument deduction seems to work fine */
int main()
{
  DerivedA* objA = new DerivedA();
  DerivedB* objB = new DerivedB();

std::cout << onlyForDerivedObjects(*objA) << std::endl; // 42
  std::cout << onlyForDerivedObjects(*objB) << std::endl; // 99

return 0;
}

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Compilation time: 0.32 sec, absolute running time: 0.14 sec, cpu time: 0 sec, memory peak: 3 Mb, absolute service time: 0,47 sec