cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations stdio/vsnprintf.c -o stdio/vsnprintf -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
stdio/vsnprintf.c:5:58: error: type specifier missing, defaults to 'int'; ISO C99 and later do not support implicit int [-Werror,-Wimplicit-int]
int (*foo)(char *restrict, size_t, const char *restrict, va_list) = vsnprintf;
                                                         ^
                                                         int
stdio/vsnprintf.c:5:7: error: incompatible function pointer types initializing 'int (*)(char *restrict, size_t, const char *restrict, int)' (aka 'int (*)(char *restrict, unsigned long, const char *restrict, int)') with an expression of type 'int (char *, unsigned long, const char *, struct __va_list_tag *)' [-Werror,-Wincompatible-function-pointer-types]
int (*foo)(char *restrict, size_t, const char *restrict, va_list) = vsnprintf;
      ^                                                             ~~~~~~~~~
2 errors generated.