changing referent of const std::string reference

Question

I'm playing around with references in C++, and noted a bit of odd behavior that I am unable to explain. My understanding is that if I have a non-const variable and a const reference to that same variable and then modify the non-const variable, the reference should reflect that modification.

Example:

void foo() {
    int x = 5;
    const int& y = x;
    x = 10;
    std::cout << "x = " << x << std::endl;
    std::cout << "y = " << y << std::endl;
}

produces the following output for me:

x = 10
y = 10

However, if I change the type to std::string, the const reference doesn't seem to reflect the modified variable:

void foo() {
    std::string x = "abc";
    const std::string& y = x;
    x = "xyz";
    std::cout << "x = " << x << std::endl;
    std::cout << "y = " << y << std::endl;
}

produces the following for me:

x = xyz
y = abc

Is this the normal expected behavior when attempting this with std::string? (I'm using GCC 4.6.0; I don't have any other compiler available at the moment, so I don't know if this is only happening with this specific version or not.)

Answer 1

Works totally fine and just as expected for me with GCC 4.3.4 and 4.5.1 aswell as offline with MSVC 10. You are not showing us the code you execute it seems, or there is a bug in 4.6.0 which I don't believe. Are you sure you're actually using a reference and not just a const std::string in your real code?