/usr/include/cereal/external/rapidjson/internal/ is in libcereal-dev 1.2.1-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/cereal/external/rapidjson/internal/biginteger.h
/usr/include/cereal/external/rapidjson/internal/diyfp.h
/usr/include/cereal/external/rapidjson/internal/dtoa.h
/usr/include/cereal/external/rapidjson/internal/ieee754.h
/usr/include/cereal/external/rapidjson/internal/itoa.h
/usr/include/cereal/external/rapidjson/internal/meta.h
/usr/include/cereal/external/rapidjson/internal/pow10.h
/usr/include/cereal/external/rapidjson/internal/regex.h
/usr/include/cereal/external/rapidjson/internal/stack.h
/usr/include/cereal/external/rapidjson/internal/strfunc.h
/usr/include/cereal/external/rapidjson/internal/strtod.h
/usr/include/cereal/external/rapidjson/internal/swap.h