Tests fail to compile: implicit instantiation of undefined template 'std::char_traits<unsigned int>'

[yuri@FreeBSD]

In file included from /usr/ports/devel/rapidjson/work/rapidjson-1.1.0-763-g24b5e7a8/test/unittest/writertest.cpp:15:
In file included from /usr/ports/devel/rapidjson/work/rapidjson-1.1.0-763-g24b5e7a8/test/unittest/unittest.h:47:
In file included from /usr/local/include/gtest/gtest.h:56:
In file included from /usr/include/c++/v1/ostream:177:
In file included from /usr/include/c++/v1/__ostream/basic_ostream.h:16:
In file included from /usr/include/c++/v1/__system_error/error_code.h:18:
In file included from /usr/include/c++/v1/__system_error/error_category.h:15: 
/usr/include/c++/v1/string:820:42: error: implicit instantiation of undefined template 'std::char_traits<unsigned int>'
  820 |   static_assert(is_same<_CharT, typename traits_type::char_type>::value,
      |                                          ^
/usr/ports/devel/rapidjson/work/rapidjson-1.1.0-763-g24b5e7a8/test/unittest/writertest.cpp:394:36: note: in instantiation of template class 'std::basic_string<unsigned int>' requested here
  394 |         EXPECT_FALSE(writer.String(s));
      |                                    ^
/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here
   23 | struct _LIBCPP_TEMPLATE_VIS char_traits;
      |                             ^
1 error generated.

Rev. 24b5e7a
clang-19
FreeBSD 14.3