C++ pointer to own struct member has different value after reassignment - c++

Question

I'm using Visual Studio 2017 and came across a bug which I cannot understand. I have this code as an example:
#include <iostream>
struct Foo
{
int a = 0;
int c;
int *b;
Foo(int n)
{
a = n;
b = &c;
}
};
struct Bar
{
Foo nestedFoo = Foo(0);
Bar(int n)
{
std::cout << "bar constructor nestedFoo before:" << std::endl;
std::cout << &nestedFoo.a << std::endl;
std::cout << nestedFoo.b << std::endl;
nestedFoo = Foo(n);
std::cout << "bar constructor nestedFoo after:" << std::endl;
std::cout << &nestedFoo.a << std::endl;
std::cout << nestedFoo.b << std::endl;
}
};
struct App
{
Bar bar = Bar(2);
};
int main()
{
App app;
Bar bar = Bar(10);
Foo foo = Foo(5);
std::cout << "foo before:" << std::endl;
std::cout << &foo.a << std::endl;
std::cout << foo.b << std::endl;
foo = Foo(20);
std::cout << "foo after:" << std::endl;
std::cout << &foo.a << std::endl;
std::cout << foo.b << std::endl;
std::cout << "bar.nestedFoo:" << std::endl;
std::cout << &bar.nestedFoo.a << std::endl;
std::cout << bar.nestedFoo.b << std::endl;
std::cout << "app.bar.nestedFoo:" << std::endl;
std::cout << &app.bar.nestedFoo.a << std::endl;
std::cout << app.bar.nestedFoo.b << std::endl;
return 0;
}
I expected the pointer and the address of the member to be the same after the reassignment but it seems this is not the case, &Foo.a and Foo.b have different values:
bar constructor nestedFoo before:
0058FEE8
0058FEE8
bar constructor nestedFoo after:
0058FEE8
0058FC24
bar constructor nestedFoo before:
0058FED8
0058FED8
bar constructor nestedFoo after:
0058FED8
0058FD04
foo before:
0058FEC8
0058FEC8
foo after:
0058FEC8
0058FDF8
bar.nestedFoo:
0058FED8
0058FD04
app.bar.nestedFoo:
0058FEE8
0058FC24
At first I thought it only happened when I had Foo as a member of another struct, but it seems to happen even at a top-level assignment. So what am I doing wrong?
Any help will be appreciated, thank you!
Edit: showing that assigning b to &c which is a member that doesn't get (explicitly) reassigned also doesn't work.