/in/foo.c: In function 'main':
/in/foo.c:5:12: warning: passing argument 1 of 'printf' makes pointer from integer without a cast [-Wint-conversion]
     printf(-1);
            ^
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:364:12: note: expected 'const char * restrict' but argument is of type 'int'
 extern int printf (const char *__restrict __format, ...);
            ^~~~~~