/in/foo.c: In function 'main':
/in/foo.c:4:5: error: unknown type name 'bool'
     bool first = true;
     ^~~~
/in/foo.c:4:18: error: 'true' undeclared (first use in this function)
     bool first = true;
                  ^~~~
/in/foo.c:4:18: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:13:21: error: 'false' undeclared (first use in this function)
             first = false;
                     ^~~~~