/usr/include/libint2/boost/preprocessor/iteration/detail/iter/ is in libint2-dev 2.3.0~beta3-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/forward1.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/forward2.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/forward3.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/forward4.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/forward5.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/reverse1.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/reverse2.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/reverse3.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/reverse4.hpp
/usr/include/libint2/boost/preprocessor/iteration/detail/iter/reverse5.hpp