Can a C++ constructor know whether it's constructing a const object?

Question

In C++, object constructors cannot be const-qualified.

But - can the constructor of an object of class A know whether it's constructing a const A or a non-const A?

_{Motivated by a fine point in the discussion regarding this question.}

Answer 1

Actually, a constructor never constructs a const object. The object is not const during construction, in the sense that the constructor code is allowed to change the object. If you call methods from within the constructor - they will be the non-const variants of methods.

Thus, in this code:

struct A {
    int foo() const { return 123; }
    int foo()       { return 456; }
    A() { x = foo(); }
    int x;
};

int bar() {
    A a;
    return a.x;
}

int baz() {
    A const a;
    return a.x;
}

both fnctions, bar() and baz(), return 456 - according to all major compilers (GodBolt).

What happens with the constructed object is simply not the constructor's business.