Cannot convert argument from "const bar" to "const int"

Question

I already posted this question but not Minimal, Complete and Verifiable. So here it is again: Given are the following 5 very small files:

main.cpp

#include "bar.h"
#include <iostream>

int main()
{
    const bar testBar;

    testBar.barTest();

    std::cin.get();
}

bar.h

#pragma once

#include "foobar.h"

class bar
{
public:
    bar();
    ~bar();

    void barTest() const;

private:
    foobar* m_pFoobar;
};

bar.cpp

#include "bar.h"

bar::bar()
{
    m_pFoobar = new foobar;
}

bar::~bar()
{
}

void bar::barTest() const
{
    m_pFoobar->fooTest(*this);
}

foo.h

#pragma once

#include "bar.h"

class foo
{
public:
    virtual void fooTest(const bar& b);
};

foobar.h

#pragma once

#include "bar.h"
#include "foo.h"

class foobar : public foo
{
public:
    foobar();
    ~foobar();

    void fooTest(const bar& b);
};

foobar.cpp

#include "foobar.h"

#include <iostream>

foobar::foobar()
{
}

foobar::~foobar()
{
}

void foobar::fooTest(const bar& b)
{
    std::cout << "SUCCESS" << std::endl;
}

When I run this code, VS2015 is telling me the following:

Error   C2664   'void foobar::fooTest(const int)': cannot convert argument 1 from 'const bar' to 'const int'    bar.cpp 14

I don't understand the reason why the compiler interprets my function with an int as argument. I hope someone can help me.