// N4606 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf
#define msg "(198)14.7.2 Explicit instantiation [temp.explicit]p397.cpp"
// Edited by Dr. Ogawa Kiyoshi. Compile procedure and results record.

#include <iostream>

template<class T> class Array {
  void mf();
};
template class Array<char>;
template void Array<int>::mf();
template<class T> void sort(Array<T>& v) { /* ... */ }
template void sort(Array<char>&); // argument is deduced here
namespace N {
template<class T> void f(T&) { }
}
template void N::f<int>(int&);

namespace N {
template<class T> class Y {
  void mf() { }
};
}
template class Y<int>; // error: class template Y not visible
// in the global namespace
using N::Y;
template class Y<int>; // error: explicit instantiation outside of the
// namespace of the template
template class N::Y<char*>; // OK: explicit instantiation in namespace N
template void N::Y<double>::mf(); // OK: explicit instantiation
// in namespace N

template<class T> class Array2 { /* ... */
};
template<class T> void sort2(Array2<T>& v) { /* ... */ }
// instantiate sort2(Array2<int>&) - template-argument deduced
template void sort2<>(Array2<int>&);

char* p = 0;
template<class T> T g(T x = &p) {
  return x;
}
template int g<int>(int); // OK even though &p isn’t an int.

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

$ ./cppgl17.sh p399
$ clang++ p399.cpp
p399.cpp:14:18: error: explicit specialization of non-template class 'X'
template<> class X<int> { /* ... */ }; // error: X not a template
                 ^~~~~~
p399.cpp:15:25: error: redefinition of 'X' as different kind of symbol
template<class T> class X;
                        ^
p399.cpp:14:18: note: previous definition is here
template<> class X<int> { /* ... */ }; // error: X not a template
                 ^
p399.cpp:16:18: error: explicit specialization of non-template class 'X'
template<> class X<char*> { /* ... */ }; // OK: X is a template
                 ^~~~~~~~
p399.cpp:16:18: error: redefinition of 'X'
p399.cpp:14:18: note: previous definition is here
template<> class X<int> { /* ... */ }; // error: X not a template
                 ^
p399.cpp:48:30: error: no function template matches function template specialization 'f'
template<> void A<short>::B::f() { /* ... */ } // error: template<> not permitted
                             ^
p399.cpp:52:1: error: template parameter list matching the non-templated nested type 'A<short>' should be empty ('template<>')
template<class U> void A<short>::C<U>::f() { /* ... */ } // error: template<> required
^       ~~~~~~~~~      ~~~~~~~~
p399.cpp:61:17: error: explicit specialization of 'sort2<String>' after instantiation
template<> void sort2<String>(Array2<String>& v); // error: specialization
                ^
p399.cpp:58:1: note: implicit instantiation first required here
sort2(v); // use primary template
^
p399.cpp:72:27: error: explicit specialization of 'E' after instantiation
template<> enum A2<char>::E : char { echar }; // ill-formed, A2<char>::E was instantiated
                          ^
p399.cpp:72:17: note: implicit instantiation first required here
template<> enum A2<char>::E : char { echar }; // ill-formed, A2<char>::E was instantiated
                ^
p399.cpp:92:9: error: variable has incomplete type 'X4<int>'
X4<int> x; // error: object of incomplete class X<int>
        ^
p399.cpp:90:18: note: forward declaration of 'X4<int>'
template<> class X4<int>;
                 ^
p399.cpp:103:16: error: expected unqualified-id
template<> int 4g<>(int) { /* ... */ } // OK: not inline
               ^
p399.cpp:106:12: error: unknown type name 'X5'
template<> X5 Q<int>::x (); // error: declares a function
           ^
p399.cpp:106:1: error: extraneous 'template<>' in declaration of variable 'Q'
template<> X5 Q<int>::x (); // error: declares a function
^~~~~~~~~~
p399.cpp:106:16: error: expected ';' at end of declaration
template<> X5 Q<int>::x (); // error: declares a function
               ^
               ;
p399.cpp:106:16: error: expected unqualified-id
p399.cpp:107:12: error: unknown type name 'X5'
template<> X5 Q<int>::x { }; // definition
           ^
p399.cpp:107:1: error: extraneous 'template<>' in declaration of variable 'Q'
template<> X5 Q<int>::x { }; // definition
^~~~~~~~~~
p399.cpp:107:16: error: expected ';' at end of declaration
template<> X5 Q<int>::x { }; // definition
               ^
               ;
p399.cpp:107:16: error: expected unqualified-id
p399.cpp:118:49: error: out-of-line definition of 'g1' does not match any declaration in 'A<T>'
template<class T> template<class X1> void A<T>::g1(T, X1) { }
                                                ^~
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

$ g++-7 p399.cpp
p399.cpp:14:18: error: 'X' is not a class template
 template<> class X<int> { /* ... */ }; // error: X not a template
                  ^
p399.cpp:14:25: error: explicit specialization of non-template 'X'
 template<> class X<int> { /* ... */ }; // error: X not a template
                         ^
p399.cpp:15:25: error: 'X' is not a template
 template<class T> class X;
                         ^
p399.cpp:14:18: note: previous declaration here
 template<> class X<int> { /* ... */ }; // error: X not a template
                  ^
p399.cpp:16:18: error: 'X' is not a class template
 template<> class X<char*> { /* ... */ }; // OK: X is a template
                  ^
p399.cpp:16:25: error: 'X' is not a template
 template<> class X<char*> { /* ... */ }; // OK: X is a template
                         ^
p399.cpp:14:18: note: previous declaration here
 template<> class X<int> { /* ... */ }; // error: X not a template
                  ^
p399.cpp:48:17: error: template-id 'f<>' for 'void A<short int>::B::f()' does not match any template declaration
 template<> void A<short>::B::f() { /* ... */ } // error: template<> not permitted
                 ^~~~~~~~
p399.cpp:46:6: note: candidate is: void A<short int>::B::f()
 void f();
      ^
p399.cpp:52:24: error: specializing member 'A<short int>::C<U>::f' requires 'template<>' syntax
 template<class U> void A<short>::C<U>::f() { /* ... */ } // error: template<> required
                        ^~~~~~~~
p399.cpp:61:48: error: specialization of 'void sort2(Array2<T>&) [with T = String]' after instantiation
 template<> void sort2<String>(Array2<String>& v); // error: specialization
                                                ^
p399.cpp:92:9: error: aggregate 'X4<int> x' has incomplete type and cannot be defined
 X4<int> x; // error: object of incomplete class X<int>
         ^
p399.cpp:103:16: error: expected unqualified-id before numeric constant
 template<> int 4g<>(int) { /* ... */ } // OK: not inline
                ^~
p399.cpp:105:12: error: 'X5' does not name a type; did you mean 'X4'?
 template<> X5 Q<int>::x; // declaration
            ^~
            X4
p399.cpp:106:12: error: 'X5' does not name a type; did you mean 'X4'?
 template<> X5 Q<int>::x (); // error: declares a function
            ^~
            X4
p399.cpp:107:12: error: 'X5' does not name a type; did you mean 'X4'?
 template<> X5 Q<int>::x { }; // definition
            ^~
            X4
p399.cpp:118:57: error: no 'void A<T>::g1(T, X1)' member function declared in class 'A<T>'
 template<class T> template<class X1> void A<T>::g1(T, X1) { }
                                                         ^
p399.cpp:149:31: error: invalid explicit specialization before '>' token
 template <class Y7> template <>
                               ^
p399.cpp:149:31: error: enclosing class templates are not explicitly specialized
p399.cpp:150:15: error: expected initializer before '<' token
 void A7<Y7>::B<double>::mf2() { } // ill-formed; B<double> is specialized but
               ^

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