```cpp The most important examples involve function calls that pass a pointer to initialized or uninitialized memory. Marking an argument with [[ref_to_uninit]] means that that argument must refer to uninitialized memory. If not, the initialization profile requires that that an argument refers to an initialized object. Consider int x [[uninit]]; using T = decltype(x); // does T accept a pointer to uninitialized memory? int f(T* [[ref_to_uninit]]); int f(T*); f(&x);