Re: Linker error with static data member in templated class

[Andy Gibbs <andyg1001 at hotmail dot co dot uk>]

Hi again,

Sorry, I think my previous demonstrator code was too simple for the target 
application in hand.  I hoped the lesson learned would translate, but in 
this case it didn't.

The following code is *much* closer to the actual code, but hopefully still 
stripping out the main complexity of it.  The actual problem I'm having 
comes where the static data member has a type that is a template class that 
takes a pointer to another member data type.  It really seems this specific, 
I'm afraid.  The "revised" demonstrator code is as follows:

template <char* T>
struct C1
 {
 C1() { }
/*C1(const C1& other) = delete;*/

 char operator()()
   { return *T; }
 };

struct C2
 {
 static char m;
 static C1<&m> op;
 };

template <typename T>
struct C3
 {
 static char m;
 static C1<&m> op1;
 static C1<&C2::m> op2;
 };

// Initialise C2::m and C2::op
char C2::m = 'a';
C1<&C2::m> C2::op;

// Initialise C3::m for type int
template<> char C3<int>::m = 'b';

// Initialise C3::op2 for type int
template <typename T> C1<&C2::m> C3<T>::op2;
template C1<&C2::m> C3<int>::op2;

// Initialise C2::op1 for type int
#if 0
/** This doesn't work **/
template <typename T> C1<&C3<T>::m> C3<T>::op1;
template C1<&C3<int>::m> C3<int>::op1;
#elif 0
/** This doesn't work either **/
template<>
C1<&C3<int>::m> C3<int>::op1;
#else
/** This requires the copy-constructor - bad! **/
template<>
C1<&C3<int>::m> C3<int>::op1 = C1<&C3<int>::m>();
#endif

int main()
 {
 printf("%c\n", C2::op());
 printf("%c\n", C3<int>::op1());
 printf("%c\n", C3<int>::op2());
 return 0;
 }


The code as presented will compile and run, but as before, I wish to disable 
the copy constructor in C1.  The two alternative syntaxes that I tried are 
in the code disabled with #if 0.  I expect that I'm missing a 'typename' or 
a 'template' keyword somewhere, but I cannot find where.

Thank you again for any help you can give me!

Andy