Why does the number of elements in a initializer list cause an ambiguous call error?

Question

Why are the first two calls to doSomething OK by the compiler, but using two elements in the list causes an ambiguous call?

#include 

        

Answer 1

Both the one-argument and three-argument lists can only match std::vector's std::initializer_list constructor. However, the two-argument list matches one of the constructors from std::vector:

template 
vector(InputIt first, InputIt last, Allocator const &alloc = Allocator());

Indeed, a char const * can be incremented, and dereferenced to get a char that is implicitly convertible to an int.