C++ Why the compiler failed with the error code C2280 when the deleted function is not used

Question

I'm trying to understand why the compiler failed with an error code C2280 (attempting to reference a deleted function) when the deleted function is never used.

Here an example of code that fails

class A {
public:
    A() { 
        cout << "default" << endl;
    }

    A(A const&) {
        cout << "copy" << endl;
    }

    A(A&&) = delete;

    A create() {
        return A();
    }
};

void main() {
    A a;
    A b(a.create());
}

And the same code that I don't understand

class A {
public:
    A() { 
        cout << "default" << endl;
    }

    A(A const&) {
        cout << "copy" << endl;
    }

    A(A&&) {
        cout << "move" << endl;
    }

    A create() {
        return A();
    }
};

void main() {
    A a;
    A b(a.create());
}

This code compiles but doesn't display "move" on the console.

The result is

default
default

Answer 1

Before C++17 copy elision was an optional optimization, but compiler still have to check that copy/move constructor available. Starting from C++17 your code will compile without error.