Using reinterpret_cast to cast a function to void*, why isn't it illegal?

Question

This is a tangential follow up to my previous question The address of a function matching a bool vs const void* overload. The answerer explained:

The

Answer 1

_{(All quotes are from N3337 and are equivalent for every single draft until N4296 from there on, i.e. this answer is valid at least for C++11 and C++14 but not for C++03 as the first quote of this answer does not exist in there.)}

[expr.reinterpret.cast]/8:

Converting a function pointer to an object pointer type or vice versa is conditionally-supported. The meaning of such a conversion is implementation-defined, except that if an implementation supports conversions in both directions, converting a prvalue of one type to the other type and back, possibly with different cv-qualification, shall yield the orignal pointer value.

This is contained in your listing. You argue that void is not an object type, but you didn't consider the crucial [basic.compound]/3:

The type of a pointer to void or a pointer to an object type is called an object pointer type.

(That is, a object pointer type is not necessarily a "pointer to object type" - standard terminology got you there.)

The only reason that

f = reinterpret_cast<decltype(f)>(s);

Isn't fine on GCC or Clang is that the target type, as opposed to the source expression, is not decayed - and you can clearly not cast void* to a function type. You need to make the target type a pointer to function, then it works.