Fix list::remove when trying to remove first element of the list (SIGSEGV)

src/utility/list.rs

@@ -113,8 +113,12 @@ impl<T: PartialEq> List<T> {
             let mut current: *mut Node<T> = self.head;
             let mut previous: *mut Node<T> = ptr::null_mut();
             while !current.is_null() {
-                if (*current).elem == item {
-                    (*previous).next = (*current).next;
+                if (&*current).elem == item {
+                    if !previous.is_null() {
+                        (*previous).next = (*current).next;
+                    } else {
+                        self.head = (*current).next;
+                    }
                     drop(Box::from_raw(current).elem);
                     return true;
                 } else {
@@ -320,6 +324,22 @@ mod test {
         assert_eq!(list.peek(), Option::None);
     }
 
+    #[test]
+    fn remove_test2() {
+        let mut list = List::default();
+        assert_eq!(list.peek(), None);
+        list.push(1);
+        list.push(2);
+        list.push(3);
+
+        assert_eq!(list.contains(&1), true);
+        list.remove(1);
+        assert_eq!(list.contains(&1), false);
+        assert_eq!(list.pop(), Option::Some(2));
+        assert_eq!(list.pop(), Option::Some(3));
+        assert_eq!(list.peek(), Option::None);
+    }
+
     #[test]
     fn miri_test() {
         let mut list = List::default();