Comment by adrianN

No, it is not statically knowable if it is actually moved.

    void foo(Obj && arg) {}

Does not move `arg`. It's fairly easy to write code that assumes `std::move` moves the value, but that can lead to bugs. For example:

    void some_function(std::vector<int> &&);
    void some_function2(std::vector<int> &&);

    void main() {
        std::vector<int> a = { 1 };
        some_function(std::move(a));

        a.push_back(2);
        some_other_function(std::move(a));
    }

The expectation is that `some_other_function` is always called with `{ 2 }`, but this will only happen if `some_function` actually moves `a`.

> Can you show an example of what you mean?

    void foo(std::unique_ptr<int, Deleter>&& p) {
        std::random_device rdev {};
        auto dist = std::uniform_int_distribution<>(0, 1);
        if (dist(rdev)) {
            auto pp = std::move(p);
        }
    }