Here’s a snippet that compiles and works:

#include <iostream>
#include <string>

void print_str(const std::string& str) {
    std::cout << str << 'n';
}

int main() {
    std::string str = "Hello world";
    print_str(std::move(str));
}

Godbolt

As far as I understand, std::move has no effect here.

Two questions:

• Is it correct that std::move isn’t harmful here, and just has no effect?
• Would it be considered good practice to use it anyway? If I don’t control print_str, and don’t need str after the call, one may say that std::move will have a positive effect if at some point print_str will be changed to get std::string by value.