To reproduce: Include the net/socket.h and sys/select.h in the same file. There are multiple errors generated due to redefinition of function names:
ncs\v1.8.0\zephyr\include\net\socket_select.h:112:17: error: redefinition of 'struct zsock_timeval'
112 | #define timeval zsock_timeval
ncs\v1.8.0\toolchain\opt\arm-none-eabi\include\sys\select.h:62:5: error: conflicting declaration of C function 'int select(int, _types_fd_set*, _types_fd_set*, _types_fd_set*, zsock_timeval*)'
62 | int select __P ((int __n, fd_set *__readfds, fd_set *__writefds,
ncs\v1.8.0\zephyr\include\net\socket_select.h:115:19: note: previous declaration 'int select(int, zsock_fd_set*, zsock_fd_set*, zsock_fd_set*, zsock_timeval*)'
115 | static inline int select(int nfds, zsock_fd_set *readfds,