error: template specialization with C linkage

[HuberyQ]

When I was building the project, I met such a mistake:
/usr/include/c++/9/tuple:875:3: error: template specialization with C linkage
875 | template<>
| ^~~~~~~~
In file included from /usr/include/features.h:461,
from /usr/include/x86_64-linux-gnu/c++/9/bits/os_defines.h:39,
from /usr/include/x86_64-linux-gnu/c++/9/bits/c++config.h:528,
from /usr/include/c++/9/iostream:38,
from file_system.cc:10:
/usr/include/string.h:28:1: note: ‘extern "C"’ linkage started here
28 | __BEGIN_DECLS
| ^~~~~~~~~~~~~
In file included from /usr/include/c++/9/bits/unique_ptr.h:37,
from /usr/include/c++/9/bits/locale_conv.h:41,
from /usr/include/c++/9/locale:43,
from /usr/include/c++/9/iomanip:43,
from ./strings.h:15,
from /usr/include/string.h:432,
from /usr/include/c++/9/cstring:42,
from file_system.cc:15:
/usr/include/c++/9/tuple:892:3: error: template with C linkage
892 | template<typename _T1, typename _T2>
| ^~~~~~~~
In file included from /usr/include/features.h:461,
from /usr/include/x86_64-linux-gnu/c++/9/bits/os_defines.h:39,
from /usr/include/x86_64-linux-gnu/c++/9/bits/c++config.h:528,
from /usr/include/c++/9/iostream:38,
from file_system.cc:10:
/usr/include/string.h:28:1: note: ‘extern "C"’ linkage started here
28 | __BEGIN_DECLS
| ^~~~~~~~~~~~~
In file included from /usr/include/c++/9/bits/unique_ptr.h:37,
from /usr/include/c++/9/bits/locale_conv.h:41,
from /usr/include/c++/9/locale:43,
from /usr/include/c++/9/iomanip:43,
from ./strings.h:15,
from /usr/include/string.h:432,
from /usr/include/c++/9/cstring:42,
from file_system.cc:15:
/usr/include/c++/9/tuple:1271:3: error: template with C linkage
1271 | template<typename... _Elements>
| ^~~~~~~~
In file included from /usr/include/features.h:461,
from /usr/include/x86_64-linux-gnu/c++/9/bits/os_defines.h:39,
from /usr/include/x86_64-linux-gnu/c++/9/bits/c++config.h:528,
from /usr/include/c++/9/iostream:38,
from file_system.cc:10:
/usr/include/string.h:28:1: note: ‘extern "C"’ linkage started here
28 | __BEGIN_DECLS
| ^~~~~~~~~~~~~
In file included from /usr/include/c++/9/bits/unique_ptr.h:37,
from /usr/include/c++/9/bits/locale_conv.h:41,
from /usr/include/c++/9/locale:43,
from /usr/include/c++/9/iomanip:43,
from ./strings.h:15,
from /usr/include/string.h:432,
from /usr/include/c++/9/cstring:42,
from file_system.cc:15:
/usr/include/c++/9/tuple:1284:3: error: template with C linkage
1284 | template<std::size_t __i, typename _Head, typename... _Tail>
| ^~~~~~~~
In file included from /usr/include/features.h:461,
from /usr/include/x86_64-linux-gnu/c++/9/bits/os_defines.h:39,
from /usr/include/x86_64-linux-gnu/c++/9/bits/c++config.h:528,
from /usr/include/c++/9/iostream:38,
from file_system.cc:10:
/usr/include/string.h:28:1: note: ‘extern "C"’ linkage started here
28 | __BEGIN_DECLS
| ^~~~~~~~~~~~~
In file included from /usr/include/c++/9/bits/unique_ptr.h:37,
from /usr/include/c++/9/bits/locale_conv.h:41,
from /usr/include/c++/9/locale:43,
from /usr/include/c++/9/iomanip:43,
from ./strings.h:15,
from /usr/include/string.h:432,
from /usr/include/c++/9/cstring:42,
from file_system.cc:15:
/usr/include/c++/9/tuple:1291:3: error: template with C linkage
1291 | template<typename _Head, typename... _Tail>
| ^~~~~~~~
In file included from /usr/include/features.h:461,
from /usr/include/x86_64-linux-gnu/c++/9/bits/os_defines.h:39,
from /usr/include/x86_64-linux-gnu/c++/9/bits/c++config.h:528,
from /usr/include/c++/9/iostream:38,
from file_system.cc:10:
/usr/include/string.h:28:1: note: ‘extern "C"’ linkage started here
28 | __BEGIN_DECLS
| ^~~~~~~~~~~~~
In file included from /usr/include/c++/9/bits/unique_ptr.h:37,
from /usr/include/c++/9/bits/locale_conv.h:41,
from /usr/include/c++/9/locale:43,
from /usr/include/c++/9/iomanip:43,
from ./strings.h:15,
from /usr/include/string.h:432,
from /usr/include/c++/9/cstring:42,
from file_system.cc:15:
/usr/include/c++/9/tuple:1300:3: error: template with C linkage
1300 | template<size_t __i>
| ^~~~~~~~
In file included from /usr/include/features.h:461,
from /usr/include/x86_64-linux-gnu/c++/9/bits/os_defines.h:39,
from /usr/include/x86_64-linux-gnu/c++/9/bits/c++config.h:528,
from /usr/include/c++/9/iostream:38,
from file_system.cc:10:

[zyl1223582136]

i hava the same problem, and i guess that contributes to mve