Add List::init_from.

GitOrigin-RevId: 17a6f374ff0b568c6e2d056053539fb2947f22d3

td/telegram/logevent/SecretChatEvent.h

@@ -322,7 +322,7 @@ class OutboundSecretMessage : public SecretChatLogEventBase<OutboundSecretMessag
 
   bool is_sent = false;
   // need send push notification to the receiver
-  // should send such messages with messages_sendEncryptedsService
+  // should send such messages with messages_sendEncryptedService
   bool need_notify_user = false;
   bool is_rewritable = false;
   // should notify our parent about state of this message (using context and random_id)

tdutils/td/utils/List.h

@@ -28,19 +28,19 @@ struct ListNode {
     if (other.empty()) {
       clear();
     } else {
-      ListNode *head = other.prev;
-      other.remove();
-      head->put(this);
+      init_from(std::move(other));
     }
   }
 
   ListNode &operator=(ListNode &&other) {
+    if (this == &other) {
+      return *this;
+    }
+
     this->remove();
 
     if (!other.empty()) {
-      ListNode *head = other.prev;
-      other.remove();
-      head->put(this);
+      init_from(std::move(other));
     }
 
     return *this;
@@ -58,11 +58,12 @@ struct ListNode {
   }
 
   void put(ListNode *other) {
-    other->connect(next);
-    this->connect(other);
+    DCHECK(other->empty());
+    put_unsafe(other);
   }
 
   void put_back(ListNode *other) {
+    DCHECK(other->empty());
     prev->connect(other);
     other->connect(this);
   }
@@ -87,6 +88,17 @@ struct ListNode {
     next = this;
     prev = this;
   }
+
+  void init_from(ListNode &&other) {
+    ListNode *head = other.prev;
+    other.remove();
+    head->put_unsafe(this);
+  }
+
+  void put_unsafe(ListNode *other) {
+    other->connect(next);
+    this->connect(other);
+  }
 };
 
 }  // namespace td