x86_64-managarm-gcc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations threads/call_once.c -o threads/call_once -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -lintl -liconv
threads/call_once.c:5:13: error: unknown type name ‘once_flag’
    5 | void (*foo)(once_flag *, void (*)(void)) = call_once;
      |             ^~~~~~~~~