qt - C++ compiler error definition of implicitly declared

Hello everyone having anissue with my code today. I have
created a program calculating area of square circle and rectangle. With a base class of
shape. Where the UML has shape as the abstract class with public area():double,
getName():string,and getDimensions:string, rectangle derived from shape with protected
height, and width, and a public rectangle(h:double, w:double), followed by a derived
square from rectangle with just a public square(h:double), and finally a circle derived
from shape with a private radius, and a public circle(r:double).
So far have
gotten far in my code yet in my shape.cpp file am getting an error on line 10 that says
shape.cpp:10: error: definition of implicitly-declared 'constexpr
shape::shape()'
shape::shape()

here
is a link to my complete code: href="https://gist.github.com/anonymous/0eedd7719a34655488fb"
rel="nofollow">https://gist.github.com/anonymous/0eedd7719a34655488fb

shape.cpp
file:

#include
            "shape.h"

#include "circle.h"
#include
            "rectangle.h"
#include "square.h"
#include
            
#include 
#include
            
using namespace
            std;

shape::shape()
{


};

your
help is appreciated