cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations wctype/towupper_l.c -o wctype/towupper_l -D_POSIX_C_SOURCE=202405L  -lm -lpthread  -liconv
wctype/towupper_l.c:5:23: error: type specifier missing, defaults to 'int' [-Werror,-Wimplicit-int]
wint_t (*foo)(wint_t, locale_t) = towupper_l;
                      ^
wctype/towupper_l.c:5:35: error: use of undeclared identifier 'towupper_l'; did you mean 'towupper'?
wint_t (*foo)(wint_t, locale_t) = towupper_l;
                                  ^~~~~~~~~~
                                  towupper
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_wctype.h:129:1: note: 'towupper' declared here
towupper(wint_t _wc)
^
wctype/towupper_l.c:5:10: error: incompatible function pointer types initializing 'wint_t (*)(wint_t, int)' (aka 'int (*)(int, int)') with an expression of type 'wint_t (wint_t)' (aka 'int (int)') [-Werror,-Wincompatible-function-pointer-types]
wint_t (*foo)(wint_t, locale_t) = towupper_l;
         ^                        ~~~~~~~~~~
3 errors generated.