7 Standard conversions [conv]

7.13 Function pointer conversions [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
:
  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
]