/in/foo.c: In function 'range':
/in/foo.c:32:13: error: unknown type name 'bool'
             bool change = false;
             ^~~~
/in/foo.c:32:27: error: 'false' undeclared (first use in this function)
             bool change = false;
                           ^~~~~
/in/foo.c:32:27: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:35:30: error: 'true' undeclared (first use in this function)
                     change = true;
                              ^~~~