compiler cannot deduce overload of std::max

Question

With my compiler

typedef const double&(*fT)(const double&, const double&);
typedef std::function<const double&(const double&, const double&)> std_func;

fT f1 = std::max<double>;                            //(1)
std_func f2 = static_cast<fT>(std::max<double>);     //(2)
std_func f3 = f1;                                    //(3) 

(1, 2, 3) work but

auto f4 = std::max<double>;                          //(4)
std_func f5 = std::max<double>;                      //(5) 

(4, 5) don't. The compiler complains about its incapability to choose the overload for case 5.

Is this behavior normal?

What is the most portable and correct way to write it?

Answer 1

There are two possible overloads of instantiation of std::max<double>: std::max(double, double) and std::max(std::initializer_list<double>). Because of that, versions 4 and 5 fail, since it can't figure out which overload matches.

Cases 1, 2 and 3 succeed because of the special rules - when taking an address of overload function, type of the result is used to select the proper overload.