cc -pthread -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations ctype/isxdigit_l.c -o ctype/isxdigit_l -D_POSIX_C_SOURCE=202405L -lm -lpthread -liconv ctype/isxdigit_l.c:5:17: error: type specifier missing, defaults to 'int' [-Werror,-Wimplicit-int] int (*foo)(int, locale_t) = isxdigit_l; ^ ctype/isxdigit_l.c:5:29: error: use of undeclared identifier 'isxdigit_l'; did you mean 'isxdigit'? int (*foo)(int, locale_t) = isxdigit_l; ^~~~~~~~~~ isxdigit /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_ctype.h:280:1: note: 'isxdigit' declared here isxdigit(int _c) ^ ctype/isxdigit_l.c:5:7: error: incompatible function pointer types initializing 'int (*)(int, int)' with an expression of type 'int (int)' [-Werror,-Wincompatible-function-pointer-types] int (*foo)(int, locale_t) = isxdigit_l; ^ ~~~~~~~~~~ 3 errors generated.