cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations wchar/open_wmemstream.c -o wchar/open_wmemstream -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -lintl -liconv
wchar/open_wmemstream.c:5:38: error: ‘open_wmemstream’ undeclared here (not in a function)
    5 | FILE *(*foo)(wchar_t **, size_t *) = open_wmemstream;
      |                                      ^~~~~~~~~~~~~~~