Given following code,
#include <sstream>
#include <stdint.h>
template <typename D> void func() {
std::basic_stringstream<D> outStream;
D suffix = 0;
outStream << suffix;
}
void main() {
func<char>(); // OK
func<wchar_t>(); // OK
func<uint16_t>(); // generates C2491
}
what does following compile error mean?
error C2491: 'std::numpunct<_Elem>::id' : definition of dllimport static data member not allowed
You can't declare methods with
_declspec(dllimport)
and provide a definition for them.
The qualifier tells the compiler that the function is imported from a different library than the one you are compiling now, so it wouldn't make sense to provide a definition for it.
When including the header, the qualifier should be
_declspec(dllimport)
and when you are compiling the module that provides a definition for the method it should be:
_declspec(dllexport)
The usual way of doing this is:
#ifdef CURRENT_MODULE
#define DLLIMPORTEXPORT _declspec(dllexport)
#else
#define DLLIMPORTEXPORT _declspec(dllimport)
#endif
The define CURRENT_MODULE is only defined in the module that contains the definitions, so when compiling that module the method is exported. All other modules that include the header don't have CURRENT_MODULE defined and the function will be imported.
I'm guessing your directive - _declspecimport - is similar to this.
