/in/foo.c:10:28: error: unknown type name 'bool'
 void insert_sort(int arr[],bool reverse,int length){
                            ^~~~
/in/foo.c: In function 'main':
/in/foo.c:41:2: warning: implicit declaration of function 'insert_sort' [-Wimplicit-function-declaration]
  insert_sort(y, true, num);
  ^~~~~~~~~~~
/in/foo.c:41:17: error: 'true' undeclared (first use in this function)
  insert_sort(y, true, num);
                 ^~~~
/in/foo.c:41:17: note: each undeclared identifier is reported only once for each function it appears in