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#include <iostream>
 
template <const char * MESSAGE> void print()
{
	std::cout << MESSAGE << '\n';
}
 
namespace
{
char namespace_message[] = "Anonymous Namespace Message";
const char namespace_const_message[] = "Anonymous Namespace Const Message";
constexpr char namespace_constexpr_message[] = "Anonymous Namespace Constexpr Message";
}
 
char message[] = "Message";
const char const_message[] = "Const Message";
constexpr char constexpr_message[] = "Constexpr Message";
 
int main()
{
	print<namespace_message>();
	print<namespace_constexpr_message>();
 
	print<message>();
	print<constexpr_message>();
 
	print<namespace_const_message>();
	print<const_message>();
	print<"Literal">();
 
	return 0;
}

prog.cpp: In function 'int main()':
prog.cpp:27:8: error: the value of '{anonymous}::namespace_const_message' is not usable in a constant expression
  print<namespace_const_message>();
        ^
prog.cpp:11:12: note: '{anonymous}::namespace_const_message' was not declared 'constexpr'
 const char namespace_const_message[] = "Anonymous Namespace Const Message";
            ^
prog.cpp:28:8: error: the value of 'const_message' is not usable in a constant expression
  print<const_message>();
        ^
prog.cpp:16:12: note: 'const_message' was not declared 'constexpr'
 const char const_message[] = "Const Message";
            ^
prog.cpp:29:19: error: no matching function for call to 'print()'
  print<"Literal">();
                   ^
prog.cpp:29:19: note: candidate is:
prog.cpp:3:38: note: template<const char* MESSAGE> void print()
 template <const char * MESSAGE> void print()
                                      ^
prog.cpp:3:38: note:   template argument deduction/substitution failed:
prog.cpp:29:19: error: '"Literal"' is not a valid template argument for type 'const char*' because string literals can never be used in this context
  print<"Literal">();
                   ^

Standard output is empty