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#include <iostream>
 
template <std::size_t SIZE> class A
{
	char b[SIZE];
 
public:
	using const_buffer_t = const char (&)[SIZE];
	using my_type = A<SIZE>;
 
	A()							: b{} { std::cout << "size: " << SIZE << " ctor 1\n"; }
	A(const_buffer_t)			: b{} { std::cout << "size: " << SIZE << " ctor 2\n"; }
    template <typename=void>
	A(const char * const)		: b{} { std::cout << "size: " << SIZE << " ctor 3\n"; }
	explicit A(const my_type &)	: b{} { std::cout << "size: " << SIZE << " ctor 4\n"; }
 
	template <std::size_t OTHER_SIZE>
	A(const char (&)[OTHER_SIZE]) : b{} { std::cout << "size: " << SIZE << " ctor 5\n"; }
 
	template <std::size_t OTHER_SIZE>
	explicit A(const A<OTHER_SIZE> &) : b{} { std::cout << "size: " << SIZE << " ctor 6\n"; }
};
 
int main()
{
	//A<5> a("five");
	A<5> b("0123456789");
	//A<9> c(a);
	A<5> d;
	A<5> e(d);
	A<9> f(d);
 
	return 0;
}

prog.cpp: In function ‘int main()’:
prog.cpp:27:21: error: call of overloaded ‘A(const char [11])’ is ambiguous
  A<5> b("0123456789");
                     ^
prog.cpp:27:21: note: candidates are:
prog.cpp:18:2: note: A<SIZE>::A(const char (&)[OTHER_SIZE]) [with unsigned int OTHER_SIZE = 11u; unsigned int SIZE = 5u]
  A(const char (&)[OTHER_SIZE]) : b{} { std::cout << "size: " << SIZE << " ctor 5\n"; }
  ^
prog.cpp:15:11: note: A<SIZE>::A(const my_type&) [with unsigned int SIZE = 5u; A<SIZE>::my_type = A<5u>]
  explicit A(const my_type &) : b{} { std::cout << "size: " << SIZE << " ctor 4\n"; }
           ^
prog.cpp:14:2: note: A<SIZE>::A(const char*) [with <template-parameter-2-1> = void; unsigned int SIZE = 5u]
  A(const char * const)  : b{} { std::cout << "size: " << SIZE << " ctor 3\n"; }
  ^

Standard output is empty