Linker error with static data member in templated class

[Andy Gibbs]

Hi,

I am using gcc 4.4.5 with the c++0x extensions turned on and am having some 
issues defining static variables inside partially specialised template 
classes.  I've put together some fairly straight-forward demonstration code 
as follows:

struct C1
 {
 C1() : i(0)
  { printf("default constructor\n"); }

 C1(const C1& other) = delete;

/*C1(const C1& other) : i(other.i)
  { printf("copy constructor\n"); }*/

 int i;
 };

struct C2
 {
 static C1 op;
 };

template <typename T>
struct C3
 {
 static C1 op;
 };

template <typename T>
struct C4
 {
 static C1 op;
 };

// Initialise C2::op
C1 C2::op;

// Initialise C3::op for type int
template<> C1 C3<int>::op;

// Initialise C4::op for type int
template<> C1 C4<int>::op = C1();


int main()
 {
 printf("%i\n", C2::op.i);
 printf("%i\n", C3<int>::op.i);
 printf("%i\n", C4<int>::op.i);
 return 0;
 }


Like this the code fails to compile with the error "deleted function 
C1::C1(const C1&) used here" referring to the line that initialises 
C4<int>::op since it appears to need the copy constructor.  I say "appears" 
since if I give C1 a copy constructor, then I find when running the code 
that it doesn't actually call the copy constructor.

However, if the compiler error is fixed, then a separate linker error 
occurs: "undefined reference to 'C3<int>::op'".  It therefore seems that it 
is not possible, at least by this syntax, to default construct C3<int>::op. 
This is in contrast to the default construction of C2::op which is possible.

Is there another syntax by which I can default construct C3<int>::op? - 
since the implementation I will need of C1 requires that the copy 
constructor be disabled and so the syntax I use with C4<int>::op is not 
going to be possible.

Thanks!

Andy