I'm trying to create a Linked List for use on the Arduino, in the Eclipse IDE with Arduino/Sloeber plugin. The linked list is written in a .h and .cpp file, and included locally in the project.  

However, when building, I get the error undefined reference to Structures::LinkedList<int>::LinkedList()

And despite the fact I've added the local folder to the list of includes (and it can find the top level file containing setup() and loop()), the problem persists;  

My relevant file listings are below, any ideas of what settings I can add to Eclipse in order to solve this? Potentially, could it be something to do with the use of template<typename T> in the header file?

My top level .cpp is pretty simple:

#include "LinkedList.h"
#include "RAStarSearch.h"
#include "Arduino.h"

using namespace Structures;
void setup() { }

void loop() {
    LinkedList<int> list = LinkedList<int>();
    return;
}

and the referenced .h is:

#ifndef LINKEDLIST_H_
#define LINKEDLIST_H_
#include "Arduino.h"

namespace Structures {
    template<typename T>
    class LinkedList {
    public:
        /// Struct inside the class LinkedList
        struct Link {
            T value;
            Link *next;
        };
    
        LinkedList<T>(); ///< Default constructor
        void addValue(T val); ///< prepends new value at beginning of list
        T popValue(); ///< returns first element and deletes Link.
        Link* peekLink(); ///< Looks at first value
    private:
        Link *head; // this is the private member variable. It is just a pointer to the first Node
    };
    const int ERRNUM = 0x8000000; ///<Error number used, as exceptions not supported
}
#endif /* LINKEDLIST_H_ */

EDIT On request I have included my code for LinkedList.cpp

#include "LinkedList.h"
#include "Arduino.h"
namespace Structures {
    template<typename T>
    LinkedList<T>::LinkedList() {
        head = NULL; // set head to NULL
    }
    template<typename T>
    void LinkedList<T>::addValue(T val) {
        Link *n = new Link();   // create new Node
        n->value = val;             // set value]

        if (head == NULL) { //i.e. if list is empty
            n->next = head;         // make the node point to the next node or NULL
            head = n;    // last but not least, make the head point at the new node.
        } else {
            Link *it = head;
            Link *oldIt = NULL;
            //TODO check edge cases i.e. insertion at beginning and end of list
            while (n->value > it->value){ //until place in list is found, needs T to have > operator
                oldIt = it;
                it = it->next;
            }
            oldIt->next = n; //Set pointer to n
            n->next = it; //Set n pointer to next
        }
    }
    template<typename T>
    T LinkedList<T>::popValue() {
        T retval = ERRNUM;
        if (head != NULL) {
            Link *n = head;
            retval = head->value;
            head = head->next;
            delete n;
        }
        return retval;
    }
    template<typename T>
    typename LinkedList<T>::Link* LinkedList<T>::peekLink() {
        return head;
    }
}

I'm trying to create a linked list for use on the Arduino, in the Eclipse IDE with the Arduino/Sloeber plugin. The linked list is written in a .h and .cpp file, and included locally in the project. 

However, when building, I get the error undefined reference to Structures::LinkedList<int>::LinkedList().

And despite the fact that I've added the local folder to the list of includes (and it can find the top level file containing setup() and loop()), the problem persists; 

My relevant file listings are below. Any ideas of what settings I can add to Eclipse in order to solve this? Potentially, could it be something to do with the use of template<typename T> in the header file?

My top level .cpp is pretty simple:

#include "LinkedList.h"
#include "RAStarSearch.h"
#include "Arduino.h"

using namespace Structures;
void setup() { }

void loop() {
  LinkedList<int> list = LinkedList<int>();
  return;
}

And the referenced .h is:

#ifndef LINKEDLIST_H_
#define LINKEDLIST_H_
#include "Arduino.h"

namespace Structures {
template<typename T>
class LinkedList {
  public:
    /// Struct inside the class LinkedList
    struct Link {
      T value;
      Link *next;
    };

    LinkedList<T>(); ///< Default constructor
    void addValue(T val); ///< prepends new value at beginning of list
    T popValue(); ///< returns first element and deletes Link.
    Link* peekLink(); ///< Looks at first value
  private:
    Link *head; // this is the private member variable. It is just a pointer to the first Node
};
const int ERRNUM = 0x8000000; ///<Error number used, as exceptions not supported
}
#endif /* LINKEDLIST_H_ */

EDIT

On request I have included my code for LinkedList.cpp

#include "LinkedList.h"
#include "Arduino.h" 

namespace Structures {
  template<typename T>
  LinkedList<T>::LinkedList() {
    head = NULL; // set head to NULL
  }
  template<typename T>
  void LinkedList<T>::addValue(T val) {
    Link *n = new Link();   // create new Node
    n->value = val;             // set value]

    if (head == NULL) { //i.e. if list is empty
      n->next = head;         // make the node point to the next node or NULL
      head = n;    // last but not least, make the head point at the new node.
    } else {
      Link *it = head;
      Link *oldIt = NULL;
      //TODO check edge cases i.e. insertion at beginning and end of list
      while (n->value > it->value){ //until place in list is found, needs T to have > operator
        oldIt = it;
        it = it->next;
      }
      oldIt->next = n; //Set pointer to n
      n->next = it; //Set n pointer to next
    }
  }
  template<typename T>
  T LinkedList<T>::popValue() {
    T retval = ERRNUM;
    if (head != NULL) {
      Link *n = head;
      retval = head->value;
      head = head->next;
      delete n;
    }
    return retval;
  }
  template<typename T>
  typename LinkedList<T>::Link* LinkedList<T>::peekLink() {
    return head;
  }
}

EDIT On request I have included my code for LinkedList.cpp

#include "LinkedList.h"
#include "Arduino.h"
namespace Structures {
    template<typename T>
    LinkedList<T>::LinkedList() {
        head = NULL; // set head to NULL
    }
    template<typename T>
    void LinkedList<T>::addValue(T val) {
        Link *n = new Link();   // create new Node
        n->value = val;             // set value]

        if (head == NULL) { //i.e. if list is empty
            n->next = head;         // make the node point to the next node or NULL
            head = n;    // last but not least, make the head point at the new node.
        } else {
            Link *it = head;
            Link *oldIt = NULL;
            //TODO check edge cases i.e. insertion at beginning and end of list
            while (n->value > it->value){ //until place in list is found, needs T to have > operator
                oldIt = it;
                it = it->next;
            }
            oldIt->next = n; //Set pointer to n
            n->next = it; //Set n pointer to next
        }
    }
    template<typename T>
    T LinkedList<T>::popValue() {
        T retval = ERRNUM;
        if (head != NULL) {
            Link *n = head;
            retval = head->value;
            head = head->next;
            delete n;
        }
        return retval;
    }
    template<typename T>
    typename LinkedList<T>::Link* LinkedList<T>::peekLink() {
        return head;
    }
}