Is conversion allowed with std::vector's template constructor taking iterators?

Question

In the C++11 standard, Section 23.3.6.2 [vector.cons], the following is said:

   template 
     vector(InputIterator first, InputI         


        

Answer 1

Since the compiler cannot distinguish between the attempt to use copy constructor of type X and the attempt to use a constructor which takes X, any implementation of

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

has to work in all compilers.

[Edit] Looks like this needs more explanation. How do I implement the above Vector constructor?

template 
vector(InputIterator first, InputIterator last,
            const Allocator& = Allocator())
{
 for(InputIterator i = first; i != last; i++)
 {
   push_back(*i);  // Or whatever way to add to vector.
 }
} 

Now any de-reference and attempt to add it local container storage *i will result in a copy constructor of the type *i (let us say type T (i.e, vector). In other words the implementation has to make a copy of the object *i and add it to the internal object collection(whatever it is). So, the template definition/implementation will be finally expanded to something like "T x(*i)". Here on wards it is just a language aspect. C++ doesn't distinguish if *i is of actually type T or *i is a type that can be implicitly converted to T.

This need not be explicitly stated in a standard.