Here is how I parse it:

For a call to a non-member function or to a static member function, the postfix expression shall either be:

- an

 lvalue that refers to a function (in which case the function-to-pointer standard conversion is suppressed on the postfix expression), or

- [a prvalue and] have function pointer type.

 

I read it as just needing function pointer type. All of the big 4 compilers agree that it need not be a prvalue; for instance, it could be an xvalue: https://godbolt.org/z/Il8sH3 .

-- 
Jason Cobb