foo.c: In function 'main':
foo.c:9:15: error: 'true' undeclared (first use in this function)
    9 |         while(true)
      |               ^~~~
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 | 
foo.c:9:15: note: each undeclared identifier is reported only once for each function it appears in
    9 |         while(true)
      |               ^~~~

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