// N4606 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf
#define msg "(174)14.5.1 Class templates [temp.class]p358-2.cpp"
// Edited by Dr. Ogawa Kiyoshi. Compile procedure and results record.

#include <iostream>

template<class T> class Array {
T* v;
int sz;
public:
explicit Array(int);
T& operator[](int);
T& elem(int i) { return v[i]; }
};

template<class T1, class T2> struct A {
void f1();
void f2();
};
template<class T2, class T1> void A<T2,T1>::f1() { } // OK
template<class T2, class T1> void A<T1,T2>::f2() { } // error
template<class ... Types> struct B {
void f3();
void f4();
};
template<class ... Types> void B<Types ...>::f3() { } // OK
template<class ... Types> void B<Types>::f4() { } // error


int main() {
  std::cout<< msg << std::endl;
  return EXIT_SUCCESS;
}

$ ./cppgl17.sh p358-2
$ clang++ p358-2.cpp
p358-2.cpp:22:45: error: nested name specifier 'A<T1, T2>::' for declaration does not refer into a class, class template or class template
      partial specialization
template<class T2, class T1> void A<T1,T2>::f2() { } // error
                                  ~~~~~~~~~~^
p358-2.cpp:28:32: error: qualifier contains unexpanded parameter pack 'Types'
template<class ... Types> void B<Types>::f4() { } // error
                               ^
2 errors generated.

$ g++-7 p358-2.cpp
p358-2.cpp:22:48: error: invalid use of incomplete type 'struct A<T1, T2>'
 template<class T2, class T1> void A<T1,T2>::f2() { } // error
                                                ^
p358-2.cpp:17:37: note: declaration of 'struct A<T1, T2>'
 template<class T1, class T2> struct A {
                                     ^
p358-2.cpp:28:45: error: invalid use of incomplete type 'struct B<Types>'
 template<class ... Types> void B<Types>::f4() { } // error
                                             ^
p358-2.cpp:23:34: note: declaration of 'struct B<Types>'
 template<class ... Types> struct B {
                                  ^

#!/bin/bash
astyle -s2 -c < $1.cpp > $1s2.cpp
cat $1s2.cpp