I've just installed g++ 4.4 and I'm playing with some of the c++0x features.
The below page describes the =default and =delete syntax. (Used to manipulate the special member functions default/copy constructor, destructor and copy assign). http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2346.htm I've managed to get parts of my code working, but it seems that defining as default a template class's special member functions outside the class definition doesn't work. I'm not really sure if it should, but looking at the suggested modifications to the spec [8.4 paragraph 7] (in the above document), I _think_ it's saying that it should work. The problem is that the compiler fails to generate the function (foo<int>::~foo() in the following code), which causes the linker to report an undefined reference. I didn't post this as a bug report as I'm not 100% sure it is a bug. === THIS CODE FAILS TO COMPILE === template <typename T> class foo { public: foo() =default; // <<--- this works fine. ~foo(); }; template <typename T> foo<T>::~foo() =default; <<--- ERROR: This doesn't get built by the compiler. // foo<T>::~foo() {}; <<-- replacing with this line fixes the error. int main() { foo<int> fi; return 0; } =================== === THIS CODE COMPILES === class foo { public: foo() =default; ~foo(); }; foo::~foo() =default; int main() { foo fi; return 0; } =================== NOTE: The reason I noticed this was that I was trying to default a virtual destructor. This should work, but I'm guessing that it must be done outside the function definition, because it doesn't work inside. However, if the above is a bug, this may also be a bug.
