[conv.fctptr]

A prvalue of type “pointer to noexcept function” can be converted to a prvalue of type “pointer to function”.

The result is a pointer to the function.

A prvalue of type “pointer to member of type noexcept function” can be converted to a prvalue of type “pointer to member of type function”.

The result designates the member function.

[Example 1: void (*p)(); void (*pp)() noexcept = &p; / error: cannot convert to pointer to noexcept function struct S { typedef void (*p)(); operator p(); }; void (*q)() noexcept = S(); / error: cannot convert to pointer to noexcept function — end example]