/in/foo.cc:1:1: error: expected unqualified-id before '>' token
 >
 ^
In file included from /usr/include/c++/6/cmath:43:0,
                 from /in/foo.cc:2:
/usr/include/c++/6/ext/type_traits.h:162:35: error: '__gnu_cxx::__is_null_pointer' declared as an 'inline' variable
   __is_null_pointer(std::nullptr_t)
                                   ^
/usr/include/c++/6/ext/type_traits.h:162:35: error: 'bool __gnu_cxx::__is_null_pointer' redeclared as different kind of symbol
/usr/include/c++/6/ext/type_traits.h:157:5: note: previous declaration 'template<class _Type> bool __gnu_cxx::__is_null_pointer(_Type)'
     __is_null_pointer(_Type)
     ^~~~~~~~~~~~~~~~~
/usr/include/c++/6/ext/type_traits.h:162:21: error: 'nullptr_t' is not a member of 'std'
   __is_null_pointer(std::nullptr_t)
                     ^~~
In file included from /usr/include/c++/6/iosfwd:40:0,
                 from /usr/include/c++/6/ios:38,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/include/c++/6/bits/postypes.h:98:11: error: 'ptrdiff_t' does not name a type
   typedef ptrdiff_t streamsize; // Signed integral type
           ^~~~~~~~~
In file included from /usr/include/c++/6/exception:172:0,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/include/c++/6/bits/exception_ptr.h:99:30: error: field 'nullptr_t' has incomplete type 'std::__exception_ptr::exception_ptr'
       exception_ptr(nullptr_t) noexcept
                              ^
/usr/include/c++/6/bits/exception_ptr.h:79:11: note: definition of 'class std::__exception_ptr::exception_ptr' is not complete until the closing brace
     class exception_ptr
           ^~~~~~~~~~~~~
/usr/include/c++/6/bits/exception_ptr.h:99:30: error: expected ';' at end of member declaration
       exception_ptr(nullptr_t) noexcept
                              ^
/usr/include/c++/6/bits/exception_ptr.h:99:32: error: expected unqualified-id before 'noexcept'
       exception_ptr(nullptr_t) noexcept
                                ^~~~~~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/include/c++/6/type_traits:359:31: error: 'std::size_t' has not been declared
   template<typename _Tp, std::size_t _Size>
                               ^~~~~~
/usr/include/c++/6/type_traits:360:25: error: '_Size' was not declared in this scope
     struct is_array<_Tp[_Size]>
                         ^~~~~
/usr/include/c++/6/type_traits:360:31: error: template argument 1 is invalid
     struct is_array<_Tp[_Size]>
                               ^
/usr/include/c++/6/type_traits:558:37: error: 'nullptr_t' is not a member of 'std'
     struct __is_null_pointer_helper<std::nullptr_t>
                                     ^~~
/usr/include/c++/6/type_traits:558:37: error: 'nullptr_t' is not a member of 'std'
/usr/include/c++/6/type_traits:558:51: error: template argument 1 is invalid
     struct __is_null_pointer_helper<std::nullptr_t>
                                                   ^
/usr/include/c++/6/type_traits:1478:32: error: 'size_t' is not a member of 'std'
     : public integral_constant<std::size_t, __alignof__(_Tp)> { };
                                ^~~
/usr/include/c++/6/type_traits:1478:32: note: suggested alternative:
In file included from /usr/include/wchar.h:51:0,
                 from /usr/include/c++/6/cwchar:44,
                 from /usr/include/c++/6/bits/postypes.h:40,
                 from /usr/include/c++/6/iosfwd:40,
                 from /usr/include/c++/6/ios:38,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/lib/gcc/x86_64-linux-gnu/6/include/stddef.h:216:23: note:   'size_t'
 typedef __SIZE_TYPE__ size_t;
                       ^~~~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/include/c++/6/type_traits:1478:32: error: 'size_t' is not a member of 'std'
     : public integral_constant<std::size_t, __alignof__(_Tp)> { };
                                ^~~
/usr/include/c++/6/type_traits:1478:32: note: suggested alternative:
In file included from /usr/include/wchar.h:51:0,
                 from /usr/include/c++/6/cwchar:44,
                 from /usr/include/c++/6/bits/postypes.h:40,
                 from /usr/include/c++/6/iosfwd:40,
                 from /usr/include/c++/6/ios:38,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/lib/gcc/x86_64-linux-gnu/6/include/stddef.h:216:23: note:   'size_t'
 typedef __SIZE_TYPE__ size_t;
                       ^~~~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/include/c++/6/type_traits:1478:61: error: template argument 1 is invalid
     : public integral_constant<std::size_t, __alignof__(_Tp)> { };
                                                             ^
/usr/include/c++/6/type_traits:1478:61: note: invalid template non-type parameter
/usr/include/c++/6/type_traits:1483:32: error: 'size_t' is not a member of 'std'
     : public integral_constant<std::size_t, 0> { };
                                ^~~
/usr/include/c++/6/type_traits:1483:32: note: suggested alternative:
In file included from /usr/include/wchar.h:51:0,
                 from /usr/include/c++/6/cwchar:44,
                 from /usr/include/c++/6/bits/postypes.h:40,
                 from /usr/include/c++/6/iosfwd:40,
                 from /usr/include/c++/6/ios:38,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/lib/gcc/x86_64-linux-gnu/6/include/stddef.h:216:23: note:   'size_t'
 typedef __SIZE_TYPE__ size_t;
                       ^~~~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h:40,
                 from /usr/include/c++/6/exception:173,
                 from /usr/include/c++/6/ios:39,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/include/c++/6/type_traits:1483:32: error: 'size_t' is not a member of 'std'
     : public integral_constant<std::size_t, 0> { };
                                ^~~
/usr/include/c++/6/type_traits:1483:32: note: suggested alternative:
In file included from /usr/include/wchar.h:51:0,
                 from /usr/include/c++/6/cwchar:44,
                 from /usr/include/c++/6/bits/postypes.h:40,
                 from /usr/include/c++/6/iosfwd:40,
                 from /usr/include/c++/6/ios:38,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:3:
/usr/lib/gcc/x86_64-linux-gnu/6/include/stddef.h:216:23: note:   'size_t'
 typedef __SIZE_TYPE__ size_t;
                       ^~~~~~
In file included from /usr/include/c++/6/bits/move.h:57:0,
                 from /usr/include/c++/6/bits/nested_exception.h