cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations ctype/isupper_l.c -o ctype/isupper_l -D_POSIX_C_SOURCE=202405L  -lm -lpthread  -liconv
ctype/isupper_l.c:5:17: error: type specifier missing, defaults to 'int'; ISO C99 and later do not support implicit int [-Wimplicit-int]
    5 | int (*foo)(int, locale_t) = isupper_l;
      |                 ^
      |                 int
ctype/isupper_l.c:5:29: error: use of undeclared identifier 'isupper_l'; did you mean 'isupper'?
    5 | int (*foo)(int, locale_t) = isupper_l;
      |                             ^~~~~~~~~
      |                             isupper
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_ctype.h:275:1: note: 'isupper' declared here
  275 | isupper(int _c)
      | ^
ctype/isupper_l.c:5:7: error: incompatible function pointer types initializing 'int (*)(int, int)' with an expression of type 'int (int)' [-Wincompatible-function-pointer-types]
    5 | int (*foo)(int, locale_t) = isupper_l;
      |       ^                     ~~~~~~~~~
3 errors generated.