Overload resolution of template functions

Question

Consider this code:

#include 

//Number1
template
auto max (T1 a, T2 b)
{
    std::cout << \"auto max(T         


        

Answer 1

For each of your function calls the compiler has 2 functions to choose from and chooses the best one. Unknown template parameters are deduced from the arguments apart from RT which must be explicitly specified and can't be deduced.

auto a = ::max(4, 7.2);

As RT is not specified and can't be deduced, the second overload is not usable so is ignored. The first is chosen and the types are deduced as int and double.

auto b = ::max(4, 7.4);

RT is now specified so the compiler can choose to either use max or max, the argument types for the 3 template parameter version match the function arguments exactly whereas the 2 template parameter version would require a cast from int to double so the 3 parameter overload is chosen.

auto c = ::max(7, 4.);

RT is now specified so the compiler can choose to either use max or max, the argument types both functions are now the same so the compiler can't choose between them.