It's undefined behavior, so it'll literally print anything. On my system with my compiler version it'll print xyz without any optimization, but if I use -O3 opt

It's undefined behavior, so it'll literally print anything. On my system with my compiler version it'll print xyz without any optimization, but if I use -O3 optimization it prints nothing. But it could just as easily segfault or print garbage from memory. Edit: If I move the first line into a function and return that string_view, then with optimizations it still prints nothing, but without optimizations it prints random varying garbage each time I run it, different each time.