foo.cc: In member function 'void LinkList::pop_front()':
foo.cc:44:7: warning: unused variable 'x' [-Wunused-variable]
   44 |   int x=head->data;
      |       ^
foo.cc: In function 'int main()':
foo.cc:39:13: warning: 'e.LinkList::head' may be used uninitialized in this function [-Wmaybe-uninitialized]
   39 |   while(head!=NULL)
      |             ^
foo.cc:96:11: note: 'e.LinkList::head' was declared here
   96 |  LinkList e;
      |           ^

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