/in/foo.c: In function 'main':
/in/foo.c:7:15: error: 'true' undeclared (first use in this function)
    7 |         while(true)
      |               ^~~~
/in/foo.c:2:1: note: 'true' is defined in header '<stdbool.h>'; did you forget to '#include <stdbool.h>'?
    1 | #include <stdio.h>
  +++ |+#include <stdbool.h>
    2 | 
/in/foo.c:7:15: note: each undeclared identifier is reported only once for each function it appears in
    7 |         while(true)
      |               ^~~~