Undefined reference to void functions from a header file

Question

I am trying to reduce the length of a long function by splitting it up into smaller components, but I encounter the error 'undefined reference to Pawn::generateCaptureMoves(Pawn, ...) const' , Pawn::generateForwardMoves(Pawn, ...) const', Pawn::generateEnPassantMoves(Pawn, ...) const' when I try to compile my file.

Pawn.h

#pragma once
#include "Piece.h"
#include <vector>

// Represents a pawn
struct Pawn : public Piece {
    Pawn(Team, int, int); // Constructor

    moveTypes calcPossibleMoves(Piece*[8][8]) const override;
    void generateCaptureMoves(Pawn p, moveTypes moves, Piece*[8][8], int) const;
    void generateForwardMoves(Pawn p, moveTypes moves, Piece*[8][8], int) const;
    void generateEnPassantMoves(Pawn p, moveTypes moves, Piece*[8][8]) const;

};

Pawn.cpp

#include "Pawn.h"
#include <vector>

Pawn::Pawn(Team team, int xPos, int yPos): Piece(team, xPos, yPos, PieceType::PAWN, "p") {}

moveTypes Pawn::calcPossibleMoves(Piece* board[8][8]) const {
    moveTypes moves;
    int dir = (getTeam() == Team::WHITE)? -1: 1;
    int xPos = getX(), yPos = getY();

    generateCaptureMoves(*this, moves, board, dir);
    generateForwardMoves(*this, moves, board, dir);
    generateEnPassantMoves(*this, moves, board);

    return moves;
};

void generateCaptureMoves(Pawn p, moveTypes moves, Piece* board[8][8], int dir) {
    // (...)
}

void generateForwardMoves(Pawn p, moveTypes moves, Piece* board[8][8], int dir){
    // (...)

}

void generateEnPassantMoves(Pawn p, moveTypes moves, Piece* board[8][8]){
    // (...)
}

---

Things I have tried

• removing the const keyword on the void function in the header file
• adding const keyword on the functions inside the .cpp file
• removing const keyword and replacing with {}

I am at a loss for ideas, can anyone help me out with this?