std::move: differences between non class types and class types

Consider the minimal example below:

#include<utility>

struct S { };

int main() {
    S s;
    std::move(s) = S{};
}

It compiles with no errors.
If I use non class types instead, I get an error.
As an example, the code below doesn't compile:

#include<utility>

int main() {
    int i;
    std::move(i) = 42;
}

The same happens with enums, scoped enums, and so on.
The error (from GCC) is:

using xvalue (rvalue reference) as lvalue

What's the rationale behind this?

I guess it's right, but I'd like to understand what's the reason for which I can do that with all the types but the non class ones.