/in/foo.c: In function 'main':
/in/foo.c:9:10: 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, ...);
            ^~~~~~
/in/foo.c:13:10: warning: passing argument 1 of 'printf' makes pointer from integer without a cast [-Wint-conversion]
   printf('2');
          ^~~
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, ...);
            ^~~~~~
/in/foo.c:17:10: warning: passing argument 1 of 'printf' makes pointer from integer without a cast [-Wint-conversion]
   printf('3');
          ^~~
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, ...);
            ^~~~~~
/in/foo.c:21:10: warning: passing argument 1 of 'printf' makes pointer from integer without a cast [-Wint-conversion]
   printf('4');
          ^~~
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, ...);
            ^~~~~~
/in/foo.c:25:10: warning: passing argument 1 of 'printf' makes pointer from integer without a cast [-Wint-conversion]
   printf('5');
          ^~~
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, ...);
            ^~~~~~