diff --git a/benchmark/bench_actor.cpp b/benchmark/bench_actor.cpp
index b13b3556f..a6939adf3 100644
--- a/benchmark/bench_actor.cpp
+++ b/benchmark/bench_actor.cpp
@@ -20,7 +20,7 @@
 #endif
 
 template <int type>
-class RingBench : public td::Benchmark {
+class RingBench final : public td::Benchmark {
  public:
   struct PassActor;
 
@@ -37,7 +37,7 @@ class RingBench : public td::Benchmark {
     return PSTRING() << "Ring (send_" << types[type] << ") (threads_n = " << thread_n_ << ")";
   }
 
-  struct PassActor : public td::Actor {
+  struct PassActor final : public td::Actor {
     int id = -1;
     td::ActorId<PassActor> next_actor;
     int start_n = 0;
@@ -118,7 +118,7 @@ class RingBench : public td::Benchmark {
 };
 
 template <int type>
-class QueryBench : public td::Benchmark {
+class QueryBench final : public td::Benchmark {
  public:
   std::string get_description() const final {
     static const char *types[] = {"callback", "immediate future", "delayed future", "dummy", "lambda", "lambda_future"};
@@ -126,7 +126,7 @@ class QueryBench : public td::Benchmark {
     return PSTRING() << "QueryBench: " << types[type];
   }
 
-  class ClientActor : public td::Actor {
+  class ClientActor final : public td::Actor {
    public:
     class Callback {
      public:
@@ -157,9 +157,9 @@ class QueryBench : public td::Benchmark {
     td::unique_ptr<Callback> callback_;
   };
 
-  class ServerActor : public td::Actor {
+  class ServerActor final : public td::Actor {
    public:
-    class ClientCallback : public ClientActor::Callback {
+    class ClientCallback final : public ClientActor::Callback {
      public:
       explicit ClientCallback(td::ActorId<ServerActor> server) : server_(server) {
       }
diff --git a/benchmark/bench_crypto.cpp b/benchmark/bench_crypto.cpp
index a37446c77..b6d36c237 100644
--- a/benchmark/bench_crypto.cpp
+++ b/benchmark/bench_crypto.cpp
@@ -29,7 +29,7 @@ static constexpr int DATA_SIZE = 8 << 10;
 static constexpr int SHORT_DATA_SIZE = 64;
 
 #if OPENSSL_VERSION_NUMBER <= 0x10100000L
-class SHA1Bench : public td::Benchmark {
+class SHA1Bench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
 
@@ -53,7 +53,7 @@ class SHA1Bench : public td::Benchmark {
 };
 #endif
 
-class AesEcbBench : public td::Benchmark {
+class AesEcbBench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
   td::UInt256 key;
@@ -84,7 +84,7 @@ class AesEcbBench : public td::Benchmark {
   }
 };
 
-class AesIgeEncryptBench : public td::Benchmark {
+class AesIgeEncryptBench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
   td::UInt256 key;
@@ -112,7 +112,7 @@ class AesIgeEncryptBench : public td::Benchmark {
   }
 };
 
-class AesIgeDecryptBench : public td::Benchmark {
+class AesIgeDecryptBench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
   td::UInt256 key;
@@ -140,7 +140,7 @@ class AesIgeDecryptBench : public td::Benchmark {
   }
 };
 
-class AesCtrBench : public td::Benchmark {
+class AesCtrBench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
   td::UInt256 key;
@@ -169,7 +169,7 @@ class AesCtrBench : public td::Benchmark {
 };
 
 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
-class AesCtrOpenSSLBench : public td::Benchmark {
+class AesCtrOpenSSLBench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
   td::UInt256 key;
@@ -205,7 +205,7 @@ class AesCtrOpenSSLBench : public td::Benchmark {
 };
 #endif
 
-class AesCbcDecryptBench : public td::Benchmark {
+class AesCbcDecryptBench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
   td::UInt256 key;
@@ -231,7 +231,7 @@ class AesCbcDecryptBench : public td::Benchmark {
   }
 };
 
-class AesCbcEncryptBench : public td::Benchmark {
+class AesCbcEncryptBench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
   td::UInt256 key;
@@ -258,7 +258,7 @@ class AesCbcEncryptBench : public td::Benchmark {
 };
 
 template <bool use_state>
-class AesIgeShortBench : public td::Benchmark {
+class AesIgeShortBench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[SHORT_DATA_SIZE];
   td::UInt256 key;
@@ -363,7 +363,7 @@ BENCH(Pbkdf2, "pbkdf2") {
   td::pbkdf2_sha256(password, salt, n, key);
 }
 
-class Crc32Bench : public td::Benchmark {
+class Crc32Bench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
 
@@ -387,7 +387,7 @@ class Crc32Bench : public td::Benchmark {
   }
 };
 
-class Crc64Bench : public td::Benchmark {
+class Crc64Bench final : public td::Benchmark {
  public:
   alignas(64) unsigned char data[DATA_SIZE];
 
diff --git a/benchmark/bench_db.cpp b/benchmark/bench_db.cpp
index ae9fd1e26..03983aab0 100644
--- a/benchmark/bench_db.cpp
+++ b/benchmark/bench_db.cpp
@@ -28,7 +28,7 @@
 #include <memory>
 
 template <class KeyValueT>
-class TdKvBench : public td::Benchmark {
+class TdKvBench final : public td::Benchmark {
   td::ConcurrentScheduler sched;
   td::string name_;
 
@@ -41,7 +41,7 @@ class TdKvBench : public td::Benchmark {
     return name_;
   }
 
-  class Main : public td::Actor {
+  class Main final : public td::Actor {
    public:
     explicit Main(int n) : n_(n) {
     }
@@ -50,7 +50,7 @@ class TdKvBench : public td::Benchmark {
     void loop() final {
       KeyValueT::destroy("test_tddb").ignore();
 
-      class Worker : public Actor {
+      class Worker final : public Actor {
        public:
         Worker(int n, td::string db_name) : n_(n) {
           kv_.init(db_name).ensure();
@@ -89,7 +89,7 @@ class TdKvBench : public td::Benchmark {
 };
 
 template <bool is_encrypted = false>
-class SqliteKVBench : public td::Benchmark {
+class SqliteKVBench final : public td::Benchmark {
   td::SqliteDb db;
   td::string get_description() const final {
     return PSTRING() << "SqliteKV " << td::tag("is_encrypted", is_encrypted);
@@ -142,7 +142,7 @@ static td::Status init_db(td::SqliteDb &db) {
   return td::Status::OK();
 }
 
-class SqliteKeyValueAsyncBench : public td::Benchmark {
+class SqliteKeyValueAsyncBench final : public td::Benchmark {
  public:
   td::string get_description() const final {
     return "SqliteKeyValueAsync";
@@ -199,7 +199,7 @@ class SqliteKeyValueAsyncBench : public td::Benchmark {
   }
 };
 
-class SeqKvBench : public td::Benchmark {
+class SeqKvBench final : public td::Benchmark {
   td::string get_description() const final {
     return "SeqKvBench";
   }
@@ -213,7 +213,7 @@ class SeqKvBench : public td::Benchmark {
 };
 
 template <bool is_encrypted = false>
-class BinlogKeyValueBench : public td::Benchmark {
+class BinlogKeyValueBench final : public td::Benchmark {
   td::string get_description() const final {
     return PSTRING() << "BinlogKeyValue " << td::tag("is_encrypted", is_encrypted);
   }
diff --git a/benchmark/bench_handshake.cpp b/benchmark/bench_handshake.cpp
index 4c8ee58c3..c3f364c2d 100644
--- a/benchmark/bench_handshake.cpp
+++ b/benchmark/bench_handshake.cpp
@@ -28,12 +28,12 @@ static string prime_base64 =
     "WC2xF40WnGvEZbDW_5yjko_vW5rk5Bj8Feg-vqD4f6n_Xu1wBQ3tKEn0e_lZ2VaFDOkphR8NgRX2NbEF7i5OFdBLJFS_b0-t8DSxBAMRnNjjuS_MW"
     "w";
 
-class HandshakeBench : public Benchmark {
+class HandshakeBench final : public Benchmark {
   std::string get_description() const final {
     return "Handshake";
   }
 
-  class FakeDhCallback : public DhCallback {
+  class FakeDhCallback final : public DhCallback {
    public:
     int is_good_prime(Slice prime_str) const final {
       auto it = cache.find(prime_str.str());
diff --git a/benchmark/bench_http.cpp b/benchmark/bench_http.cpp
index 9bbcc163c..835d5a83f 100644
--- a/benchmark/bench_http.cpp
+++ b/benchmark/bench_http.cpp
@@ -24,7 +24,7 @@ namespace td {
 
 std::atomic<int> counter;
 
-class HttpClient : public HttpOutboundConnection::Callback {
+class HttpClient final : public HttpOutboundConnection::Callback {
   void start_up() final {
     IPAddress addr;
     addr.init_ipv4_port("127.0.0.1", 8082).ensure();
diff --git a/benchmark/bench_http_reader.cpp b/benchmark/bench_http_reader.cpp
index b6d4651a0..a37c9718c 100644
--- a/benchmark/bench_http_reader.cpp
+++ b/benchmark/bench_http_reader.cpp
@@ -16,7 +16,7 @@
 static std::string http_query = "GET / HTTP/1.1\r\nConnection:keep-alive\r\nhost:127.0.0.1:8080\r\n\r\n";
 static const size_t block_size = 2500;
 
-class HttpReaderBench : public td::Benchmark {
+class HttpReaderBench final : public td::Benchmark {
   std::string get_description() const final {
     return "HttpReaderBench";
   }
@@ -52,7 +52,7 @@ class HttpReaderBench : public td::Benchmark {
   }
 };
 
-class BufferBench : public td::Benchmark {
+class BufferBench final : public td::Benchmark {
   std::string get_description() const final {
     return "BufferBench";
   }
@@ -78,7 +78,7 @@ class BufferBench : public td::Benchmark {
   }
 };
 
-class FindBoundaryBench : public td::Benchmark {
+class FindBoundaryBench final : public td::Benchmark {
   std::string get_description() const final {
     return "FindBoundaryBench";
   }
diff --git a/benchmark/bench_http_server.cpp b/benchmark/bench_http_server.cpp
index ca548c2d8..cf6f4e4c6 100644
--- a/benchmark/bench_http_server.cpp
+++ b/benchmark/bench_http_server.cpp
@@ -21,7 +21,7 @@ namespace td {
 
 static int cnt = 0;
 
-class HelloWorld : public HttpInboundConnection::Callback {
+class HelloWorld final : public HttpInboundConnection::Callback {
  public:
   void handle(unique_ptr<HttpQuery> query, ActorOwn<HttpInboundConnection> connection) final {
     // LOG(ERROR) << *query;
@@ -47,7 +47,7 @@ class HelloWorld : public HttpInboundConnection::Callback {
 };
 
 const int N = 0;
-class Server : public TcpListener::Callback {
+class Server final : public TcpListener::Callback {
  public:
   void start_up() final {
     listener_ = create_actor<TcpListener>("Listener", 8082, ActorOwn<TcpListener::Callback>(actor_id(this)));
diff --git a/benchmark/bench_http_server_cheat.cpp b/benchmark/bench_http_server_cheat.cpp
index f5cdb7a67..98e8c7a98 100644
--- a/benchmark/bench_http_server_cheat.cpp
+++ b/benchmark/bench_http_server_cheat.cpp
@@ -24,7 +24,7 @@ namespace td {
 
 // HttpInboundConnection header
 static int cnt = 0;
-class HelloWorld : public Actor {
+class HelloWorld final : public Actor {
  public:
   explicit HelloWorld(SocketFd socket_fd) : socket_fd_(std::move(socket_fd)) {
   }
@@ -98,7 +98,7 @@ class HelloWorld : public Actor {
   }
 };
 const int N = 0;
-class Server : public TcpListener::Callback {
+class Server final : public TcpListener::Callback {
  public:
   void start_up() final {
     listener_ = create_actor<TcpListener>("Listener", 8082, ActorOwn<TcpListener::Callback>(actor_id(this)));
diff --git a/benchmark/bench_http_server_fast.cpp b/benchmark/bench_http_server_fast.cpp
index 874582c43..1d2896346 100644
--- a/benchmark/bench_http_server_fast.cpp
+++ b/benchmark/bench_http_server_fast.cpp
@@ -22,7 +22,7 @@
 
 namespace td {
 
-class HttpEchoConnection : public Actor {
+class HttpEchoConnection final : public Actor {
  public:
   explicit HttpEchoConnection(SocketFd fd) : fd_(std::move(fd)) {
   }
@@ -85,7 +85,7 @@ class HttpEchoConnection : public Actor {
 };
 
 const int N = 8;
-class Server : public TcpListener::Callback {
+class Server final : public TcpListener::Callback {
  public:
   void start_up() final {
     listener_ = create_actor<TcpListener>("Listener", 8082, ActorOwn<TcpListener::Callback>(actor_id(this)));
diff --git a/benchmark/bench_log.cpp b/benchmark/bench_log.cpp
index 723d8931b..fa42828d8 100644
--- a/benchmark/bench_log.cpp
+++ b/benchmark/bench_log.cpp
@@ -36,7 +36,7 @@ std::string create_tmp_file() {
 #endif
 }
 
-class IostreamWriteBench : public td::Benchmark {
+class IostreamWriteBench final : public td::Benchmark {
  protected:
   std::string file_name_;
   std::ofstream stream;
@@ -67,7 +67,7 @@ class IostreamWriteBench : public td::Benchmark {
   }
 };
 
-class FILEWriteBench : public td::Benchmark {
+class FILEWriteBench final : public td::Benchmark {
  protected:
   std::string file_name_;
   FILE *file;
@@ -101,7 +101,7 @@ class FILEWriteBench : public td::Benchmark {
 #if TD_ANDROID
 #include <android/log.h>
 #define ALOG(...) __android_log_print(ANDROID_LOG_VERBOSE, "XXX", __VA_ARGS__)
-class ALogWriteBench : public td::Benchmark {
+class ALogWriteBench final : public td::Benchmark {
  public:
   std::string get_description() const final {
     return "android_log";
@@ -118,7 +118,7 @@ class ALogWriteBench : public td::Benchmark {
 };
 #endif
 
-class LogWriteBench : public td::Benchmark {
+class LogWriteBench final : public td::Benchmark {
  protected:
   std::string file_name_;
   std::ofstream stream;
diff --git a/benchmark/bench_misc.cpp b/benchmark/bench_misc.cpp
index 0b956b99f..fb412a1ad 100644
--- a/benchmark/bench_misc.cpp
+++ b/benchmark/bench_misc.cpp
@@ -119,7 +119,7 @@ BENCH(Time, "Clocks::monotonic") {
 }
 */
 #if !TD_WINDOWS
-class PipeBench : public Benchmark {
+class PipeBench final : public Benchmark {
  public:
   int p[2];
 
@@ -153,7 +153,7 @@ class PipeBench : public Benchmark {
 #endif
 
 #if TD_LINUX || TD_ANDROID || TD_TIZEN
-class SemBench : public Benchmark {
+class SemBench final : public Benchmark {
   sem_t sem;
 
  public:
@@ -180,7 +180,7 @@ class SemBench : public Benchmark {
 #endif
 
 #if !TD_WINDOWS
-class UtimeBench : public Benchmark {
+class UtimeBench final : public Benchmark {
  public:
   void start_up() final {
     FileFd::open("test", FileFd::Flags::Create | FileFd::Flags::Write).move_as_ok().close();
@@ -210,7 +210,7 @@ BENCH(Pwrite, "pwrite") {
   fd.close();
 }
 
-class CreateFileBench : public Benchmark {
+class CreateFileBench final : public Benchmark {
   string get_description() const final {
     return "create_file";
   }
@@ -233,7 +233,7 @@ class CreateFileBench : public Benchmark {
   }
 };
 
-class WalkPathBench : public Benchmark {
+class WalkPathBench final : public Benchmark {
   string get_description() const final {
     return "walk_path";
   }
@@ -266,7 +266,7 @@ class WalkPathBench : public Benchmark {
 
 #if !TD_THREAD_UNSUPPORTED
 template <int ThreadN = 2>
-class AtomicReleaseIncBench : public Benchmark {
+class AtomicReleaseIncBench final : public Benchmark {
   string get_description() const final {
     return PSTRING() << "AtomicReleaseInc" << ThreadN;
   }
@@ -290,7 +290,7 @@ template <int ThreadN>
 std::atomic<uint64> AtomicReleaseIncBench<ThreadN>::a_;
 
 template <int ThreadN = 2>
-class AtomicReleaseCasIncBench : public Benchmark {
+class AtomicReleaseCasIncBench final : public Benchmark {
   string get_description() const final {
     return PSTRING() << "AtomicReleaseCasInc" << ThreadN;
   }
@@ -316,7 +316,7 @@ template <int ThreadN>
 std::atomic<uint64> AtomicReleaseCasIncBench<ThreadN>::a_;
 
 template <int ThreadN = 2>
-class RwMutexReadBench : public Benchmark {
+class RwMutexReadBench final : public Benchmark {
   string get_description() const final {
     return PSTRING() << "RwMutexRead" << ThreadN;
   }
@@ -336,7 +336,7 @@ class RwMutexReadBench : public Benchmark {
   }
 };
 template <int ThreadN = 2>
-class RwMutexWriteBench : public Benchmark {
+class RwMutexWriteBench final : public Benchmark {
   string get_description() const final {
     return PSTRING() << "RwMutexWrite" << ThreadN;
   }
diff --git a/benchmark/bench_queue.cpp b/benchmark/bench_queue.cpp
index 008f2f641..749a37770 100644
--- a/benchmark/bench_queue.cpp
+++ b/benchmark/bench_queue.cpp
@@ -562,7 +562,7 @@ class SemCheatQueue {
 };
 
 template <class QueueT>
-class QueueBenchmark2 : public td::Benchmark {
+class QueueBenchmark2 final : public td::Benchmark {
   QueueT client, server;
   int connections_n, queries_n;
 
@@ -704,7 +704,7 @@ class QueueBenchmark2 : public td::Benchmark {
 };
 
 template <class QueueT>
-class QueueBenchmark : public td::Benchmark {
+class QueueBenchmark final : public td::Benchmark {
   QueueT client, server;
   const int connections_n;
   int queries_n;
@@ -836,7 +836,7 @@ class QueueBenchmark : public td::Benchmark {
 };
 
 template <class QueueT>
-class RingBenchmark : public td::Benchmark {
+class RingBenchmark final : public td::Benchmark {
   static constexpr int QN = 504;
 
   struct Thread {
diff --git a/benchmark/bench_tddb.cpp b/benchmark/bench_tddb.cpp
index 5f82a153d..8427a877d 100644
--- a/benchmark/bench_tddb.cpp
+++ b/benchmark/bench_tddb.cpp
@@ -37,7 +37,7 @@ static Status init_db(SqliteDb &db) {
   return Status::OK();
 }
 
-class MessagesDbBench : public Benchmark {
+class MessagesDbBench final : public Benchmark {
  public:
   string get_description() const final {
     return "MessagesDb";
diff --git a/td/generate/tl_writer_c.h b/td/generate/tl_writer_c.h
index b3a81e6a1..030afe620 100644
--- a/td/generate/tl_writer_c.h
+++ b/td/generate/tl_writer_c.h
@@ -16,7 +16,7 @@
 
 namespace td {
 
-class TlWriterCCommon : public tl::TL_writer {
+class TlWriterCCommon final : public tl::TL_writer {
  public:
   int is_header_;
   std::string prefix_;
@@ -547,7 +547,7 @@ class TlWriterCCommon : public tl::TL_writer {
     }
   };
 
-  struct file_store_methods_to_td : public file_store_methods {
+  struct file_store_methods_to_td final : public file_store_methods {
     explicit file_store_methods_to_td(const class TlWriterCCommon *cl) : cl(cl) {
     }
     void store_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
@@ -609,7 +609,7 @@ class TlWriterCCommon : public tl::TL_writer {
     const class TlWriterCCommon *cl;
   };
 
-  struct file_store_methods_destroy : public file_store_methods {
+  struct file_store_methods_destroy final : public file_store_methods {
     explicit file_store_methods_destroy(const class TlWriterCCommon *cl) : cl(cl) {
     }
     void store_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
@@ -666,7 +666,7 @@ class TlWriterCCommon : public tl::TL_writer {
     }
     const class TlWriterCCommon *cl;
   };
-  struct file_store_methods_stack : public file_store_methods {
+  struct file_store_methods_stack final : public file_store_methods {
     explicit file_store_methods_stack(const class TlWriterCCommon *cl) : cl(cl) {
     }
     void store_simple_type(std::stringstream &ss, std::string offset, std::string res_var, std::string var,
@@ -767,7 +767,7 @@ class TlWriterCCommon : public tl::TL_writer {
     }
   };
 
-  struct file_fetch_methods_from_td : public file_fetch_methods {
+  struct file_fetch_methods_from_td final : public file_fetch_methods {
     explicit file_fetch_methods_from_td(const class TlWriterCCommon *cl) : cl(cl) {
     }
     std::string fetch_field_start(std::stringstream &ss, std::string offset, int depth,
@@ -818,7 +818,7 @@ class TlWriterCCommon : public tl::TL_writer {
     const class TlWriterCCommon *cl;
   };
 
-  struct file_fetch_methods_stack : public file_fetch_methods {
+  struct file_fetch_methods_stack final : public file_fetch_methods {
     explicit file_fetch_methods_stack(const class TlWriterCCommon *cl) : cl(cl) {
     }
     std::string fetch_field_start(std::stringstream &ss, std::string offset, int depth,
diff --git a/td/generate/tl_writer_dotnet.h b/td/generate/tl_writer_dotnet.h
index 0fbcadcc4..62dd0b1d8 100644
--- a/td/generate/tl_writer_dotnet.h
+++ b/td/generate/tl_writer_dotnet.h
@@ -17,7 +17,7 @@
 namespace td {
 namespace tl {
 
-class TlWriterDotNet : public TL_writer {
+class TlWriterDotNet final : public TL_writer {
  public:
   bool is_header_;
   std::string prefix_;
diff --git a/td/generate/tl_writer_hpp.h b/td/generate/tl_writer_hpp.h
index adb985d80..04b96d8d2 100644
--- a/td/generate/tl_writer_hpp.h
+++ b/td/generate/tl_writer_hpp.h
@@ -14,7 +14,7 @@
 
 namespace td {
 
-class TD_TL_writer_hpp : public TD_TL_writer {
+class TD_TL_writer_hpp final : public TD_TL_writer {
  public:
   TD_TL_writer_hpp(const std::string &tl_name, const std::string &string_type, const std::string &bytes_type)
       : TD_TL_writer(tl_name, string_type, bytes_type) {
diff --git a/td/generate/tl_writer_java.h b/td/generate/tl_writer_java.h
index 0789165cf..6a3a17f71 100644
--- a/td/generate/tl_writer_java.h
+++ b/td/generate/tl_writer_java.h
@@ -14,7 +14,7 @@
 
 namespace td {
 
-class TD_TL_writer_java : public tl::TL_writer {
+class TD_TL_writer_java final : public tl::TL_writer {
   static const int MAX_ARITY = 0;
 
   static const std::string base_type_class_names[MAX_ARITY + 1];
diff --git a/td/generate/tl_writer_jni_cpp.h b/td/generate/tl_writer_jni_cpp.h
index d4b4d8262..18e47afe9 100644
--- a/td/generate/tl_writer_jni_cpp.h
+++ b/td/generate/tl_writer_jni_cpp.h
@@ -15,7 +15,7 @@
 
 namespace td {
 
-class TD_TL_writer_jni_cpp : public TD_TL_writer_cpp {
+class TD_TL_writer_jni_cpp final : public TD_TL_writer_cpp {
   std::string gen_vector_fetch(std::string field_name, const tl::tl_tree_type *t,
                                const std::vector<tl::var_description> &vars, int parser_type) const;
 
diff --git a/td/generate/tl_writer_jni_h.h b/td/generate/tl_writer_jni_h.h
index ed6401ba1..97059f788 100644
--- a/td/generate/tl_writer_jni_h.h
+++ b/td/generate/tl_writer_jni_h.h
@@ -13,7 +13,7 @@
 
 namespace td {
 
-class TD_TL_writer_jni_h : public TD_TL_writer_h {
+class TD_TL_writer_jni_h final : public TD_TL_writer_h {
  public:
   TD_TL_writer_jni_h(const std::string &tl_name, const std::string &string_type, const std::string &bytes_type,
                      const std::vector<std::string> &ext_include)
diff --git a/td/mtproto/HandshakeActor.h b/td/mtproto/HandshakeActor.h
index c239b9e4f..a49b56f89 100644
--- a/td/mtproto/HandshakeActor.h
+++ b/td/mtproto/HandshakeActor.h
@@ -19,7 +19,7 @@ namespace td {
 namespace mtproto {
 
 // Has Raw connection. Generates new auth key. And returns it and raw_connection. Or error...
-class HandshakeActor : public Actor {
+class HandshakeActor final : public Actor {
  public:
   HandshakeActor(unique_ptr<AuthKeyHandshake> handshake, unique_ptr<RawConnection> raw_connection,
                  unique_ptr<AuthKeyHandshakeContext> context, double timeout,
diff --git a/td/mtproto/HandshakeConnection.h b/td/mtproto/HandshakeConnection.h
index bbcc41835..f7760ce05 100644
--- a/td/mtproto/HandshakeConnection.h
+++ b/td/mtproto/HandshakeConnection.h
@@ -24,7 +24,7 @@
 namespace td {
 namespace mtproto {
 
-class HandshakeConnection
+class HandshakeConnection final
     : private RawConnection::Callback
     , private AuthKeyHandshake::Callback {
  public:
diff --git a/td/mtproto/HttpTransport.h b/td/mtproto/HttpTransport.h
index a1ec209c2..e246a0428 100644
--- a/td/mtproto/HttpTransport.h
+++ b/td/mtproto/HttpTransport.h
@@ -21,7 +21,7 @@ namespace td {
 namespace mtproto {
 namespace http {
 
-class Transport : public IStreamTransport {
+class Transport final : public IStreamTransport {
  public:
   explicit Transport(string secret) : secret_(std::move(secret)) {
   }
diff --git a/td/mtproto/PacketStorer.h b/td/mtproto/PacketStorer.h
index e8d6532f0..c71b33f81 100644
--- a/td/mtproto/PacketStorer.h
+++ b/td/mtproto/PacketStorer.h
@@ -15,7 +15,7 @@ namespace td {
 namespace mtproto {
 
 template <class Impl>
-class PacketStorer
+class PacketStorer final
     : public Storer
     , public Impl {
  public:
diff --git a/td/mtproto/Ping.cpp b/td/mtproto/Ping.cpp
index e9d5a7e4d..b3dadcc7c 100644
--- a/td/mtproto/Ping.cpp
+++ b/td/mtproto/Ping.cpp
@@ -21,7 +21,7 @@ namespace mtproto {
 
 ActorOwn<> create_ping_actor(string debug, unique_ptr<RawConnection> raw_connection, unique_ptr<AuthData> auth_data,
                              Promise<unique_ptr<RawConnection>> promise, ActorShared<> parent) {
-  class PingActor : public Actor {
+  class PingActor final : public Actor {
    public:
     PingActor(unique_ptr<RawConnection> raw_connection, unique_ptr<AuthData> auth_data,
               Promise<unique_ptr<RawConnection>> promise, ActorShared<> parent)
diff --git a/td/mtproto/PingConnection.cpp b/td/mtproto/PingConnection.cpp
index 52631fd04..92945ea39 100644
--- a/td/mtproto/PingConnection.cpp
+++ b/td/mtproto/PingConnection.cpp
@@ -27,7 +27,7 @@ namespace td {
 namespace mtproto {
 namespace detail {
 
-class PingConnectionReqPQ
+class PingConnectionReqPQ final
     : public PingConnection
     , private RawConnection::Callback {
  public:
@@ -86,7 +86,7 @@ class PingConnectionReqPQ
   bool was_ping_ = false;
 };
 
-class PingConnectionPingPong
+class PingConnectionPingPong final
     : public PingConnection
     , private SessionConnection::Callback {
  public:
diff --git a/td/mtproto/RawConnection.cpp b/td/mtproto/RawConnection.cpp
index 5da655f98..e4b5d6086 100644
--- a/td/mtproto/RawConnection.cpp
+++ b/td/mtproto/RawConnection.cpp
@@ -33,7 +33,7 @@
 namespace td {
 namespace mtproto {
 
-class RawConnectionDefault : public RawConnection {
+class RawConnectionDefault final : public RawConnection {
  public:
   RawConnectionDefault(SocketFd socket_fd, TransportType transport_type, unique_ptr<StatsCallback> stats_callback)
       : socket_fd_(std::move(socket_fd))
@@ -260,7 +260,7 @@ class RawConnectionDefault : public RawConnection {
 };
 
 #if TD_EXPERIMENTAL_WATCH_OS
-class RawConnectionHttp : public RawConnection {
+class RawConnectionHttp final : public RawConnection {
  public:
   RawConnectionHttp(IPAddress ip_address, unique_ptr<StatsCallback> stats_callback)
       : ip_address_(std::move(ip_address)), stats_callback_(std::move(stats_callback)) {
diff --git a/td/mtproto/SessionConnection.h b/td/mtproto/SessionConnection.h
index 5bc3cd786..bb43dd25f 100644
--- a/td/mtproto/SessionConnection.h
+++ b/td/mtproto/SessionConnection.h
@@ -65,7 +65,7 @@ inline StringBuilder &operator<<(StringBuilder &stream, const MsgInfo &id) {
                 << "] [seq_no:" << format::as_hex(id.seq_no) << "]";
 }
 
-class SessionConnection
+class SessionConnection final
     : public Named
     , private RawConnection::Callback {
  public:
diff --git a/td/mtproto/TcpTransport.h b/td/mtproto/TcpTransport.h
index b57d6e836..73866132d 100644
--- a/td/mtproto/TcpTransport.h
+++ b/td/mtproto/TcpTransport.h
@@ -49,7 +49,7 @@ class ITransport {
   virtual ~ITransport() = default;
 };
 
-class AbridgedTransport : public ITransport {
+class AbridgedTransport final : public ITransport {
  public:
   size_t read_from_stream(ChainBufferReader *stream, BufferSlice *message, uint32 *quick_ack) final;
   void write_prepare_inplace(BufferWriter *message, bool quick_ack) final;
@@ -79,7 +79,7 @@ class IntermediateTransport : ITransport {
 
 using TransportImpl = IntermediateTransport;
 
-class OldTransport : public IStreamTransport {
+class OldTransport final : public IStreamTransport {
  public:
   OldTransport() = default;
   Result<size_t> read_next(BufferSlice *message, uint32 *quick_ack) final TD_WARN_UNUSED_RESULT {
@@ -126,7 +126,7 @@ class OldTransport : public IStreamTransport {
   ChainBufferWriter *output_;
 };
 
-class ObfuscatedTransport : public IStreamTransport {
+class ObfuscatedTransport final : public IStreamTransport {
  public:
   ObfuscatedTransport(int16 dc_id, const ProxySecret &secret)
       : dc_id_(dc_id), secret_(secret), impl_(secret_.use_random_padding()) {
diff --git a/td/mtproto/TlsInit.h b/td/mtproto/TlsInit.h
index acc7d0e58..c9a0fa4a9 100644
--- a/td/mtproto/TlsInit.h
+++ b/td/mtproto/TlsInit.h
@@ -23,7 +23,7 @@ class Grease {
   static void init(MutableSlice res);
 };
 
-class TlsInit : public TransparentProxy {
+class TlsInit final : public TransparentProxy {
  public:
   TlsInit(SocketFd socket_fd, string domain, string secret, unique_ptr<Callback> callback, ActorShared<> parent,
           double server_time_difference)
diff --git a/td/mtproto/utils.h b/td/mtproto/utils.h
index 97c9af31e..083f01c52 100644
--- a/td/mtproto/utils.h
+++ b/td/mtproto/utils.h
@@ -18,7 +18,7 @@ template <class T>
 using TLStorer = DefaultStorer<T>;
 
 template <class T>
-class TLObjectStorer : public Storer {
+class TLObjectStorer final : public Storer {
   mutable size_t size_ = std::numeric_limits<size_t>::max();
   const T &object_;
 
diff --git a/td/telegram/AnimationsManager.cpp b/td/telegram/AnimationsManager.cpp
index 2f6d8aa9b..a75b554c9 100644
--- a/td/telegram/AnimationsManager.cpp
+++ b/td/telegram/AnimationsManager.cpp
@@ -38,7 +38,7 @@
 
 namespace td {
 
-class GetSavedGifsQuery : public Td::ResultHandler {
+class GetSavedGifsQuery final : public Td::ResultHandler {
   bool is_repair_ = false;
 
  public:
@@ -66,7 +66,7 @@ class GetSavedGifsQuery : public Td::ResultHandler {
   }
 };
 
-class SaveGifQuery : public Td::ResultHandler {
+class SaveGifQuery final : public Td::ResultHandler {
   FileId file_id_;
   string file_reference_;
   bool unsave_ = false;
diff --git a/td/telegram/AnimationsManager.h b/td/telegram/AnimationsManager.h
index 4bff114cd..ee0ea546d 100644
--- a/td/telegram/AnimationsManager.h
+++ b/td/telegram/AnimationsManager.h
@@ -27,7 +27,7 @@ namespace td {
 
 class Td;
 
-class AnimationsManager : public Actor {
+class AnimationsManager final : public Actor {
  public:
   AnimationsManager(Td *td, ActorShared<> parent);
 
diff --git a/td/telegram/AuthManager.h b/td/telegram/AuthManager.h
index 66aeb4327..d1850f508 100644
--- a/td/telegram/AuthManager.h
+++ b/td/telegram/AuthManager.h
@@ -23,7 +23,7 @@
 
 namespace td {
 
-class AuthManager : public NetActor {
+class AuthManager final : public NetActor {
  public:
   AuthManager(int32 api_id, const string &api_hash, ActorShared<> parent);
 
diff --git a/td/telegram/AutoDownloadSettings.cpp b/td/telegram/AutoDownloadSettings.cpp
index 79a5108c8..59ffe2386 100644
--- a/td/telegram/AutoDownloadSettings.cpp
+++ b/td/telegram/AutoDownloadSettings.cpp
@@ -30,7 +30,7 @@ static td_api::object_ptr<td_api::autoDownloadSettings> convert_auto_download_se
       settings->video_upload_maxbitrate_, video_preload_large, audio_preload_next, phonecalls_less_data);
 }
 
-class GetAutoDownloadSettingsQuery : public Td::ResultHandler {
+class GetAutoDownloadSettingsQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::autoDownloadSettingsPresets>> promise_;
 
  public:
@@ -79,7 +79,7 @@ telegram_api::object_ptr<telegram_api::autoDownloadSettings> get_input_auto_down
       settings.max_video_file_size, settings.max_other_file_size, settings.video_upload_bitrate);
 }
 
-class SaveAutoDownloadSettingsQuery : public Td::ResultHandler {
+class SaveAutoDownloadSettingsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
diff --git a/td/telegram/BackgroundManager.cpp b/td/telegram/BackgroundManager.cpp
index 328bcbfd8..0d8859d96 100644
--- a/td/telegram/BackgroundManager.cpp
+++ b/td/telegram/BackgroundManager.cpp
@@ -40,7 +40,7 @@
 
 namespace td {
 
-class GetBackgroundQuery : public Td::ResultHandler {
+class GetBackgroundQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   BackgroundId background_id_;
   string background_name_;
@@ -75,7 +75,7 @@ class GetBackgroundQuery : public Td::ResultHandler {
   }
 };
 
-class GetBackgroundsQuery : public Td::ResultHandler {
+class GetBackgroundsQuery final : public Td::ResultHandler {
   Promise<telegram_api::object_ptr<telegram_api::account_WallPapers>> promise_;
 
  public:
@@ -101,7 +101,7 @@ class GetBackgroundsQuery : public Td::ResultHandler {
   }
 };
 
-class InstallBackgroundQuery : public Td::ResultHandler {
+class InstallBackgroundQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -128,7 +128,7 @@ class InstallBackgroundQuery : public Td::ResultHandler {
   }
 };
 
-class UploadBackgroundQuery : public Td::ResultHandler {
+class UploadBackgroundQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   FileId file_id_;
   BackgroundType type_;
@@ -174,7 +174,7 @@ class UploadBackgroundQuery : public Td::ResultHandler {
   }
 };
 
-class UnsaveBackgroundQuery : public Td::ResultHandler {
+class UnsaveBackgroundQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -205,7 +205,7 @@ class UnsaveBackgroundQuery : public Td::ResultHandler {
   }
 };
 
-class ResetBackgroundsQuery : public Td::ResultHandler {
+class ResetBackgroundsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -235,7 +235,7 @@ class ResetBackgroundsQuery : public Td::ResultHandler {
   }
 };
 
-class BackgroundManager::UploadBackgroundFileCallback : public FileManager::UploadCallback {
+class BackgroundManager::UploadBackgroundFileCallback final : public FileManager::UploadCallback {
  public:
   void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) final {
     send_closure_later(G()->background_manager(), &BackgroundManager::on_upload_background_file, file_id,
diff --git a/td/telegram/BackgroundManager.h b/td/telegram/BackgroundManager.h
index df1490d28..7df9486b4 100644
--- a/td/telegram/BackgroundManager.h
+++ b/td/telegram/BackgroundManager.h
@@ -29,7 +29,7 @@ namespace td {
 
 class Td;
 
-class BackgroundManager : public Actor {
+class BackgroundManager final : public Actor {
  public:
   BackgroundManager(Td *td, ActorShared<> parent);
 
diff --git a/td/telegram/BotCommand.cpp b/td/telegram/BotCommand.cpp
index af915cd07..4cf4e8193 100644
--- a/td/telegram/BotCommand.cpp
+++ b/td/telegram/BotCommand.cpp
@@ -22,7 +22,7 @@
 
 namespace td {
 
-class SetBotCommandsQuery : public Td::ResultHandler {
+class SetBotCommandsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -52,7 +52,7 @@ class SetBotCommandsQuery : public Td::ResultHandler {
   }
 };
 
-class ResetBotCommandsQuery : public Td::ResultHandler {
+class ResetBotCommandsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -78,7 +78,7 @@ class ResetBotCommandsQuery : public Td::ResultHandler {
   }
 };
 
-class GetBotCommandsQuery : public Td::ResultHandler {
+class GetBotCommandsQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::botCommands>> promise_;
 
  public:
diff --git a/td/telegram/CallActor.h b/td/telegram/CallActor.h
index a4e39f8b5..ffff2afae 100644
--- a/td/telegram/CallActor.h
+++ b/td/telegram/CallActor.h
@@ -89,7 +89,7 @@ struct CallState {
   tl_object_ptr<td_api::CallState> get_call_state_object() const;
 };
 
-class CallActor : public NetQueryCallback {
+class CallActor final : public NetQueryCallback {
  public:
   CallActor(CallId call_id, ActorShared<> parent, Promise<int64> promise);
 
diff --git a/td/telegram/CallManager.h b/td/telegram/CallManager.h
index 931b1b381..85fb3f6b2 100644
--- a/td/telegram/CallManager.h
+++ b/td/telegram/CallManager.h
@@ -22,7 +22,7 @@
 
 namespace td {
 
-class CallManager : public Actor {
+class CallManager final : public Actor {
  public:
   using Update = telegram_api::object_ptr<telegram_api::updatePhoneCall>;
   explicit CallManager(ActorShared<> parent);
diff --git a/td/telegram/CallbackQueriesManager.cpp b/td/telegram/CallbackQueriesManager.cpp
index 145071fbd..38dfafab5 100644
--- a/td/telegram/CallbackQueriesManager.cpp
+++ b/td/telegram/CallbackQueriesManager.cpp
@@ -28,7 +28,7 @@
 
 namespace td {
 
-class GetBotCallbackAnswerQuery : public Td::ResultHandler {
+class GetBotCallbackAnswerQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int64 result_id_;
   DialogId dialog_id_;
@@ -97,7 +97,7 @@ class GetBotCallbackAnswerQuery : public Td::ResultHandler {
   }
 };
 
-class SetBotCallbackAnswerQuery : public Td::ResultHandler {
+class SetBotCallbackAnswerQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
diff --git a/td/telegram/Client.cpp b/td/telegram/Client.cpp
index ff6cd82a5..503329d66 100644
--- a/td/telegram/Client.cpp
+++ b/td/telegram/Client.cpp
@@ -47,7 +47,7 @@ class TdReceiver {
   }
 
   unique_ptr<TdCallback> create_callback(ClientManager::ClientId client_id) {
-    class Callback : public TdCallback {
+    class Callback final : public TdCallback {
      public:
       Callback(ClientManager::ClientId client_id, TdReceiver *impl) : client_id_(client_id), impl_(impl) {
       }
@@ -231,7 +231,7 @@ class Client::Impl final {
 
 #else
 
-class MultiTd : public Actor {
+class MultiTd final : public Actor {
  public:
   explicit MultiTd(Td::Options options) : options_(std::move(options)) {
   }
@@ -287,7 +287,7 @@ class TdReceiver {
   }
 
   unique_ptr<TdCallback> create_callback(ClientManager::ClientId client_id) {
-    class Callback : public TdCallback {
+    class Callback final : public TdCallback {
      public:
       explicit Callback(ClientManager::ClientId client_id, std::shared_ptr<OutputQueue> output_queue)
           : client_id_(client_id), output_queue_(std::move(output_queue)) {
diff --git a/td/telegram/ClientActor.h b/td/telegram/ClientActor.h
index 9d211cd00..34ac11794 100644
--- a/td/telegram/ClientActor.h
+++ b/td/telegram/ClientActor.h
@@ -27,7 +27,7 @@ class Td;
  * This is a low-level Actor interface for interaction with TDLib. The interface is a lot more flexible than
  * the Client interface, however, for most usages the Client interface should be sufficient.
  */
-class ClientActor : public Actor {
+class ClientActor final : public Actor {
  public:
   /// Options for ClientActor creation.
   struct Options {
diff --git a/td/telegram/ConfigManager.cpp b/td/telegram/ConfigManager.cpp
index 0299febe2..6bec29eb9 100644
--- a/td/telegram/ConfigManager.cpp
+++ b/td/telegram/ConfigManager.cpp
@@ -379,7 +379,7 @@ ActorOwn<> get_simple_config_firebase_firestore(Promise<SimpleConfigResult> prom
 }
 
 ActorOwn<> get_full_config(DcOption option, Promise<FullConfig> promise, ActorShared<> parent) {
-  class SessionCallback : public Session::Callback {
+  class SessionCallback final : public Session::Callback {
    public:
     SessionCallback(ActorShared<> parent, DcOption option) : parent_(std::move(parent)), option_(std::move(option)) {
     }
@@ -417,7 +417,7 @@ ActorOwn<> get_full_config(DcOption option, Promise<FullConfig> promise, ActorSh
     std::vector<Promise<unique_ptr<mtproto::RawConnection>>> delay_forever_;
   };
 
-  class SimpleAuthData : public AuthDataShared {
+  class SimpleAuthData final : public AuthDataShared {
    public:
     explicit SimpleAuthData(DcId dc_id) : dc_id_(dc_id) {
     }
@@ -487,7 +487,7 @@ ActorOwn<> get_full_config(DcOption option, Promise<FullConfig> promise, ActorSh
     }
   };
 
-  class GetConfigActor : public NetQueryCallback {
+  class GetConfigActor final : public NetQueryCallback {
    public:
     GetConfigActor(DcOption option, Promise<FullConfig> promise, ActorShared<> parent)
         : option_(std::move(option)), promise_(std::move(promise)), parent_(std::move(parent)) {
@@ -542,7 +542,7 @@ ActorOwn<> get_full_config(DcOption option, Promise<FullConfig> promise, ActorSh
   return ActorOwn<>(create_actor<GetConfigActor>("GetConfigActor", option, std::move(promise), std::move(parent)));
 }
 
-class ConfigRecoverer : public Actor {
+class ConfigRecoverer final : public Actor {
  public:
   explicit ConfigRecoverer(ActorShared<> parent) : parent_(std::move(parent)) {
     connecting_since_ = Time::now();
@@ -840,7 +840,7 @@ class ConfigRecoverer : public Actor {
   }
 
   void start_up() final {
-    class StateCallback : public StateManager::Callback {
+    class StateCallback final : public StateManager::Callback {
      public:
       explicit StateCallback(ActorId<ConfigRecoverer> parent) : parent_(std::move(parent)) {
       }
diff --git a/td/telegram/ConfigManager.h b/td/telegram/ConfigManager.h
index 0cf265ffa..65caf655b 100644
--- a/td/telegram/ConfigManager.h
+++ b/td/telegram/ConfigManager.h
@@ -83,7 +83,7 @@ using FullConfig = tl_object_ptr<telegram_api::config>;
 ActorOwn<> get_full_config(DcId dc_id, IPAddress ip_address, Promise<FullConfig> promise);
 
 class ConfigRecoverer;
-class ConfigManager : public NetQueryCallback {
+class ConfigManager final : public NetQueryCallback {
  public:
   explicit ConfigManager(ActorShared<> parent);
 
diff --git a/td/telegram/ContactsManager.cpp b/td/telegram/ContactsManager.cpp
index 74d050ce7..8c887e680 100644
--- a/td/telegram/ContactsManager.cpp
+++ b/td/telegram/ContactsManager.cpp
@@ -75,7 +75,7 @@
 
 namespace td {
 
-class DismissSuggestionQuery : public Td::ResultHandler {
+class DismissSuggestionQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -107,7 +107,7 @@ class DismissSuggestionQuery : public Td::ResultHandler {
   }
 };
 
-class SetAccountTtlQuery : public Td::ResultHandler {
+class SetAccountTtlQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -138,7 +138,7 @@ class SetAccountTtlQuery : public Td::ResultHandler {
   }
 };
 
-class GetAccountTtlQuery : public Td::ResultHandler {
+class GetAccountTtlQuery final : public Td::ResultHandler {
   Promise<int32> promise_;
 
  public:
@@ -166,7 +166,7 @@ class GetAccountTtlQuery : public Td::ResultHandler {
   }
 };
 
-class AcceptLoginTokenQuery : public Td::ResultHandler {
+class AcceptLoginTokenQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::session>> promise_;
 
  public:
@@ -193,7 +193,7 @@ class AcceptLoginTokenQuery : public Td::ResultHandler {
   }
 };
 
-class GetAuthorizationsQuery : public Td::ResultHandler {
+class GetAuthorizationsQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::sessions>> promise_;
 
  public:
@@ -234,7 +234,7 @@ class GetAuthorizationsQuery : public Td::ResultHandler {
   }
 };
 
-class ResetAuthorizationQuery : public Td::ResultHandler {
+class ResetAuthorizationQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -261,7 +261,7 @@ class ResetAuthorizationQuery : public Td::ResultHandler {
   }
 };
 
-class ResetAuthorizationsQuery : public Td::ResultHandler {
+class ResetAuthorizationsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -289,7 +289,7 @@ class ResetAuthorizationsQuery : public Td::ResultHandler {
   }
 };
 
-class GetWebAuthorizationsQuery : public Td::ResultHandler {
+class GetWebAuthorizationsQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::connectedWebsites>> promise_;
 
  public:
@@ -337,7 +337,7 @@ class GetWebAuthorizationsQuery : public Td::ResultHandler {
   }
 };
 
-class ResetWebAuthorizationQuery : public Td::ResultHandler {
+class ResetWebAuthorizationQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -364,7 +364,7 @@ class ResetWebAuthorizationQuery : public Td::ResultHandler {
   }
 };
 
-class ResetWebAuthorizationsQuery : public Td::ResultHandler {
+class ResetWebAuthorizationsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -391,7 +391,7 @@ class ResetWebAuthorizationsQuery : public Td::ResultHandler {
   }
 };
 
-class GetContactsQuery : public Td::ResultHandler {
+class GetContactsQuery final : public Td::ResultHandler {
  public:
   void send(int32 hash) {
     LOG(INFO) << "Reload contacts with hash " << hash;
@@ -415,7 +415,7 @@ class GetContactsQuery : public Td::ResultHandler {
   }
 };
 
-class GetContactsStatusesQuery : public Td::ResultHandler {
+class GetContactsStatusesQuery final : public Td::ResultHandler {
  public:
   void send() {
     LOG(INFO) << "Reload contacts statuses";
@@ -438,7 +438,7 @@ class GetContactsStatusesQuery : public Td::ResultHandler {
   }
 };
 
-class AddContactQuery : public Td::ResultHandler {
+class AddContactQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   UserId user_id_;
 
@@ -475,7 +475,7 @@ class AddContactQuery : public Td::ResultHandler {
   }
 };
 
-class AcceptContactQuery : public Td::ResultHandler {
+class AcceptContactQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   UserId user_id_;
 
@@ -506,7 +506,7 @@ class AcceptContactQuery : public Td::ResultHandler {
   }
 };
 
-class ImportContactsQuery : public Td::ResultHandler {
+class ImportContactsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   vector<Contact> input_contacts_;
   vector<UserId> imported_user_ids_;
@@ -609,7 +609,7 @@ class ImportContactsQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteContactsQuery : public Td::ResultHandler {
+class DeleteContactsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -637,7 +637,7 @@ class DeleteContactsQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteContactsByPhoneNumberQuery : public Td::ResultHandler {
+class DeleteContactsByPhoneNumberQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   vector<UserId> user_ids_;
 
@@ -674,7 +674,7 @@ class DeleteContactsByPhoneNumberQuery : public Td::ResultHandler {
   }
 };
 
-class ResetContactsQuery : public Td::ResultHandler {
+class ResetContactsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -708,7 +708,7 @@ class ResetContactsQuery : public Td::ResultHandler {
   }
 };
 
-class SearchDialogsNearbyQuery : public Td::ResultHandler {
+class SearchDialogsNearbyQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::Updates>> promise_;
 
  public:
@@ -742,7 +742,7 @@ class SearchDialogsNearbyQuery : public Td::ResultHandler {
   }
 };
 
-class UploadProfilePhotoQuery : public Td::ResultHandler {
+class UploadProfilePhotoQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   FileId file_id_;
 
@@ -795,7 +795,7 @@ class UploadProfilePhotoQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateProfilePhotoQuery : public Td::ResultHandler {
+class UpdateProfilePhotoQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   FileId file_id_;
   int64 old_photo_id_;
@@ -849,7 +849,7 @@ class UpdateProfilePhotoQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteProfilePhotoQuery : public Td::ResultHandler {
+class DeleteProfilePhotoQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int64 profile_photo_id_;
 
@@ -885,7 +885,7 @@ class DeleteProfilePhotoQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateProfileQuery : public Td::ResultHandler {
+class UpdateProfileQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int32 flags_;
   string first_name_;
@@ -923,7 +923,7 @@ class UpdateProfileQuery : public Td::ResultHandler {
   }
 };
 
-class CheckUsernameQuery : public Td::ResultHandler {
+class CheckUsernameQuery final : public Td::ResultHandler {
   Promise<bool> promise_;
 
  public:
@@ -948,7 +948,7 @@ class CheckUsernameQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateUsernameQuery : public Td::ResultHandler {
+class UpdateUsernameQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -979,7 +979,7 @@ class UpdateUsernameQuery : public Td::ResultHandler {
   }
 };
 
-class CheckChannelUsernameQuery : public Td::ResultHandler {
+class CheckChannelUsernameQuery final : public Td::ResultHandler {
   Promise<bool> promise_;
   ChannelId channel_id_;
   string username_;
@@ -1018,7 +1018,7 @@ class CheckChannelUsernameQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateChannelUsernameQuery : public Td::ResultHandler {
+class UpdateChannelUsernameQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   string username_;
@@ -1066,7 +1066,7 @@ class UpdateChannelUsernameQuery : public Td::ResultHandler {
   }
 };
 
-class SetChannelStickerSetQuery : public Td::ResultHandler {
+class SetChannelStickerSetQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   StickerSetId sticker_set_id_;
@@ -1115,7 +1115,7 @@ class SetChannelStickerSetQuery : public Td::ResultHandler {
   }
 };
 
-class ToggleChannelSignaturesQuery : public Td::ResultHandler {
+class ToggleChannelSignaturesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -1155,7 +1155,7 @@ class ToggleChannelSignaturesQuery : public Td::ResultHandler {
   }
 };
 
-class TogglePrehistoryHiddenQuery : public Td::ResultHandler {
+class TogglePrehistoryHiddenQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   bool is_all_history_available_;
@@ -1208,7 +1208,7 @@ class TogglePrehistoryHiddenQuery : public Td::ResultHandler {
   }
 };
 
-class ConvertToGigagroupQuery : public Td::ResultHandler {
+class ConvertToGigagroupQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -1247,7 +1247,7 @@ class ConvertToGigagroupQuery : public Td::ResultHandler {
   }
 };
 
-class EditChatAboutQuery : public Td::ResultHandler {
+class EditChatAboutQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   string about_;
@@ -1309,7 +1309,7 @@ class EditChatAboutQuery : public Td::ResultHandler {
   }
 };
 
-class SetDiscussionGroupQuery : public Td::ResultHandler {
+class SetDiscussionGroupQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId broadcast_channel_id_;
   ChannelId group_channel_id_;
@@ -1348,7 +1348,7 @@ class SetDiscussionGroupQuery : public Td::ResultHandler {
   }
 };
 
-class EditLocationQuery : public Td::ResultHandler {
+class EditLocationQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   DialogLocation location_;
@@ -1387,7 +1387,7 @@ class EditLocationQuery : public Td::ResultHandler {
   }
 };
 
-class ToggleSlowModeQuery : public Td::ResultHandler {
+class ToggleSlowModeQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   int32 slow_mode_delay_ = 0;
@@ -1441,7 +1441,7 @@ class ToggleSlowModeQuery : public Td::ResultHandler {
   }
 };
 
-class ReportChannelSpamQuery : public Td::ResultHandler {
+class ReportChannelSpamQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -1482,7 +1482,7 @@ class ReportChannelSpamQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteChatQuery : public Td::ResultHandler {
+class DeleteChatQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -1510,7 +1510,7 @@ class DeleteChatQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteChannelQuery : public Td::ResultHandler {
+class DeleteChannelQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -1542,7 +1542,7 @@ class DeleteChannelQuery : public Td::ResultHandler {
   }
 };
 
-class AddChatUserQuery : public Td::ResultHandler {
+class AddChatUserQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -1571,7 +1571,7 @@ class AddChatUserQuery : public Td::ResultHandler {
   }
 };
 
-class EditChatAdminQuery : public Td::ResultHandler {
+class EditChatAdminQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChatId chat_id_;
 
@@ -1607,7 +1607,7 @@ class EditChatAdminQuery : public Td::ResultHandler {
   }
 };
 
-class ExportChatInviteQuery : public Td::ResultHandler {
+class ExportChatInviteQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::chatInviteLink>> promise_;
   DialogId dialog_id_;
 
@@ -1666,7 +1666,7 @@ class ExportChatInviteQuery : public Td::ResultHandler {
   }
 };
 
-class EditChatInviteLinkQuery : public Td::ResultHandler {
+class EditChatInviteLinkQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::chatInviteLink>> promise_;
   DialogId dialog_id_;
 
@@ -1718,7 +1718,7 @@ class EditChatInviteLinkQuery : public Td::ResultHandler {
   }
 };
 
-class GetExportedChatInviteQuery : public Td::ResultHandler {
+class GetExportedChatInviteQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::chatInviteLink>> promise_;
   DialogId dialog_id_;
 
@@ -1768,7 +1768,7 @@ class GetExportedChatInviteQuery : public Td::ResultHandler {
   }
 };
 
-class GetExportedChatInvitesQuery : public Td::ResultHandler {
+class GetExportedChatInvitesQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::chatInviteLinks>> promise_;
   DialogId dialog_id_;
 
@@ -1836,7 +1836,7 @@ class GetExportedChatInvitesQuery : public Td::ResultHandler {
   }
 };
 
-class GetChatAdminWithInvitesQuery : public Td::ResultHandler {
+class GetChatAdminWithInvitesQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::chatInviteLinkCounts>> promise_;
   DialogId dialog_id_;
 
@@ -1886,7 +1886,7 @@ class GetChatAdminWithInvitesQuery : public Td::ResultHandler {
   }
 };
 
-class GetChatInviteImportersQuery : public Td::ResultHandler {
+class GetChatInviteImportersQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::chatInviteLinkMembers>> promise_;
   DialogId dialog_id_;
 
@@ -1947,7 +1947,7 @@ class GetChatInviteImportersQuery : public Td::ResultHandler {
   }
 };
 
-class RevokeChatInviteLinkQuery : public Td::ResultHandler {
+class RevokeChatInviteLinkQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::chatInviteLinks>> promise_;
   DialogId dialog_id_;
 
@@ -2022,7 +2022,7 @@ class RevokeChatInviteLinkQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteExportedChatInviteQuery : public Td::ResultHandler {
+class DeleteExportedChatInviteQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -2056,7 +2056,7 @@ class DeleteExportedChatInviteQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteRevokedExportedChatInvitesQuery : public Td::ResultHandler {
+class DeleteRevokedExportedChatInvitesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -2093,7 +2093,7 @@ class DeleteRevokedExportedChatInvitesQuery : public Td::ResultHandler {
   }
 };
 
-class CheckChatInviteQuery : public Td::ResultHandler {
+class CheckChatInviteQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   string invite_link_;
 
@@ -2124,7 +2124,7 @@ class CheckChatInviteQuery : public Td::ResultHandler {
   }
 };
 
-class ImportChatInviteQuery : public Td::ResultHandler {
+class ImportChatInviteQuery final : public Td::ResultHandler {
   Promise<DialogId> promise_;
 
   string invite_link_;
@@ -2168,7 +2168,7 @@ class ImportChatInviteQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteChatUserQuery : public Td::ResultHandler {
+class DeleteChatUserQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2201,7 +2201,7 @@ class DeleteChatUserQuery : public Td::ResultHandler {
   }
 };
 
-class JoinChannelQuery : public Td::ResultHandler {
+class JoinChannelQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2234,7 +2234,7 @@ class JoinChannelQuery : public Td::ResultHandler {
   }
 };
 
-class InviteToChannelQuery : public Td::ResultHandler {
+class InviteToChannelQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2269,7 +2269,7 @@ class InviteToChannelQuery : public Td::ResultHandler {
   }
 };
 
-class EditChannelAdminQuery : public Td::ResultHandler {
+class EditChannelAdminQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2304,7 +2304,7 @@ class EditChannelAdminQuery : public Td::ResultHandler {
   }
 };
 
-class EditChannelBannedQuery : public Td::ResultHandler {
+class EditChannelBannedQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2339,7 +2339,7 @@ class EditChannelBannedQuery : public Td::ResultHandler {
   }
 };
 
-class LeaveChannelQuery : public Td::ResultHandler {
+class LeaveChannelQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2372,7 +2372,7 @@ class LeaveChannelQuery : public Td::ResultHandler {
   }
 };
 
-class CanEditChannelCreatorQuery : public Td::ResultHandler {
+class CanEditChannelCreatorQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2403,7 +2403,7 @@ class CanEditChannelCreatorQuery : public Td::ResultHandler {
   }
 };
 
-class EditChannelCreatorQuery : public Td::ResultHandler {
+class EditChannelCreatorQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2445,7 +2445,7 @@ class EditChannelCreatorQuery : public Td::ResultHandler {
   }
 };
 
-class MigrateChatQuery : public Td::ResultHandler {
+class MigrateChatQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2473,7 +2473,7 @@ class MigrateChatQuery : public Td::ResultHandler {
   }
 };
 
-class GetCreatedPublicChannelsQuery : public Td::ResultHandler {
+class GetCreatedPublicChannelsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   PublicDialogType type_;
 
@@ -2527,7 +2527,7 @@ class GetCreatedPublicChannelsQuery : public Td::ResultHandler {
   }
 };
 
-class GetGroupsForDiscussionQuery : public Td::ResultHandler {
+class GetGroupsForDiscussionQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2571,7 +2571,7 @@ class GetGroupsForDiscussionQuery : public Td::ResultHandler {
   }
 };
 
-class GetInactiveChannelsQuery : public Td::ResultHandler {
+class GetInactiveChannelsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2602,7 +2602,7 @@ class GetInactiveChannelsQuery : public Td::ResultHandler {
   }
 };
 
-class GetUsersQuery : public Td::ResultHandler {
+class GetUsersQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2629,7 +2629,7 @@ class GetUsersQuery : public Td::ResultHandler {
   }
 };
 
-class GetFullUserQuery : public Td::ResultHandler {
+class GetFullUserQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2656,7 +2656,7 @@ class GetFullUserQuery : public Td::ResultHandler {
   }
 };
 
-class GetUserPhotosQuery : public Td::ResultHandler {
+class GetUserPhotosQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   UserId user_id_;
   int32 offset_;
@@ -2709,7 +2709,7 @@ class GetUserPhotosQuery : public Td::ResultHandler {
   }
 };
 
-class GetChatsQuery : public Td::ResultHandler {
+class GetChatsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2752,7 +2752,7 @@ class GetChatsQuery : public Td::ResultHandler {
   }
 };
 
-class GetFullChatQuery : public Td::ResultHandler {
+class GetFullChatQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChatId chat_id_;
 
@@ -2783,7 +2783,7 @@ class GetFullChatQuery : public Td::ResultHandler {
   }
 };
 
-class GetChannelsQuery : public Td::ResultHandler {
+class GetChannelsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2836,7 +2836,7 @@ class GetChannelsQuery : public Td::ResultHandler {
   }
 };
 
-class GetFullChannelQuery : public Td::ResultHandler {
+class GetFullChannelQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2868,7 +2868,7 @@ class GetFullChannelQuery : public Td::ResultHandler {
   }
 };
 
-class GetChannelParticipantQuery : public Td::ResultHandler {
+class GetChannelParticipantQuery final : public Td::ResultHandler {
   Promise<DialogParticipant> promise_;
   ChannelId channel_id_;
   DialogId participant_dialog_id_;
@@ -2921,7 +2921,7 @@ class GetChannelParticipantQuery : public Td::ResultHandler {
   }
 };
 
-class GetChannelParticipantsQuery : public Td::ResultHandler {
+class GetChannelParticipantsQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::channels_channelParticipants>> promise_;
   ChannelId channel_id_;
 
@@ -2968,7 +2968,7 @@ class GetChannelParticipantsQuery : public Td::ResultHandler {
   }
 };
 
-class GetChannelAdministratorsQuery : public Td::ResultHandler {
+class GetChannelAdministratorsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -3038,7 +3038,7 @@ class GetChannelAdministratorsQuery : public Td::ResultHandler {
   }
 };
 
-class GetSupportUserQuery : public Td::ResultHandler {
+class GetSupportUserQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -3180,7 +3180,7 @@ tl_object_ptr<td_api::chatStatisticsChannel> ContactsManager::convert_broadcast_
       convert_stats_graph(std::move(obj->iv_interactions_graph_)), std::move(recent_message_interactions));
 }
 
-class GetMegagroupStatsQuery : public Td::ResultHandler {
+class GetMegagroupStatsQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::ChatStatistics>> promise_;
   ChannelId channel_id_;
 
@@ -3218,7 +3218,7 @@ class GetMegagroupStatsQuery : public Td::ResultHandler {
   }
 };
 
-class GetBroadcastStatsQuery : public Td::ResultHandler {
+class GetBroadcastStatsQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::ChatStatistics>> promise_;
   ChannelId channel_id_;
 
@@ -3267,7 +3267,7 @@ tl_object_ptr<td_api::messageStatistics> ContactsManager::convert_message_stats(
   return make_tl_object<td_api::messageStatistics>(convert_stats_graph(std::move(obj->views_graph_)));
 }
 
-class GetMessageStatsQuery : public Td::ResultHandler {
+class GetMessageStatsQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::messageStatistics>> promise_;
   ChannelId channel_id_;
 
@@ -3307,7 +3307,7 @@ class GetMessageStatsQuery : public Td::ResultHandler {
   }
 };
 
-class LoadAsyncGraphQuery : public Td::ResultHandler {
+class LoadAsyncGraphQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::StatisticalGraph>> promise_;
 
  public:
@@ -3338,7 +3338,7 @@ class LoadAsyncGraphQuery : public Td::ResultHandler {
   }
 };
 
-class ContactsManager::UploadProfilePhotoCallback : public FileManager::UploadCallback {
+class ContactsManager::UploadProfilePhotoCallback final : public FileManager::UploadCallback {
  public:
   void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) final {
     send_closure_later(G()->contacts_manager(), &ContactsManager::on_upload_profile_photo, file_id,
diff --git a/td/telegram/ContactsManager.h b/td/telegram/ContactsManager.h
index 4bfebe948..09561a5d5 100644
--- a/td/telegram/ContactsManager.h
+++ b/td/telegram/ContactsManager.h
@@ -58,7 +58,7 @@ struct BinlogEvent;
 
 class Td;
 
-class ContactsManager : public Actor {
+class ContactsManager final : public Actor {
  public:
   ContactsManager(Td *td, ActorShared<> parent);
   ContactsManager(const ContactsManager &) = delete;
diff --git a/td/telegram/CountryInfoManager.cpp b/td/telegram/CountryInfoManager.cpp
index 06f313fb3..6ae7e9302 100644
--- a/td/telegram/CountryInfoManager.cpp
+++ b/td/telegram/CountryInfoManager.cpp
@@ -25,7 +25,7 @@
 
 namespace td {
 
-class GetNearestDcQuery : public Td::ResultHandler {
+class GetNearestDcQuery final : public Td::ResultHandler {
   Promise<string> promise_;
 
  public:
@@ -54,7 +54,7 @@ class GetNearestDcQuery : public Td::ResultHandler {
   }
 };
 
-class GetCountriesListQuery : public Td::ResultHandler {
+class GetCountriesListQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::help_CountriesList>> promise_;
 
  public:
diff --git a/td/telegram/CountryInfoManager.h b/td/telegram/CountryInfoManager.h
index 48267ab98..22ee605df 100644
--- a/td/telegram/CountryInfoManager.h
+++ b/td/telegram/CountryInfoManager.h
@@ -21,7 +21,7 @@ namespace td {
 
 class Td;
 
-class CountryInfoManager : public Actor {
+class CountryInfoManager final : public Actor {
  public:
   CountryInfoManager(Td *td, ActorShared<> parent);
 
diff --git a/td/telegram/DelayDispatcher.h b/td/telegram/DelayDispatcher.h
index e96952106..a741b82e8 100644
--- a/td/telegram/DelayDispatcher.h
+++ b/td/telegram/DelayDispatcher.h
@@ -16,7 +16,7 @@
 
 namespace td {
 
-class DelayDispatcher : public Actor {
+class DelayDispatcher final : public Actor {
  public:
   DelayDispatcher(double default_delay, ActorShared<> parent)
       : default_delay_(default_delay), parent_(std::move(parent)) {
diff --git a/td/telegram/DeviceTokenManager.h b/td/telegram/DeviceTokenManager.h
index bc5e70844..685dfac93 100644
--- a/td/telegram/DeviceTokenManager.h
+++ b/td/telegram/DeviceTokenManager.h
@@ -22,7 +22,7 @@
 
 namespace td {
 
-class DeviceTokenManager : public NetQueryCallback {
+class DeviceTokenManager final : public NetQueryCallback {
  public:
   explicit DeviceTokenManager(ActorShared<> parent) : parent_(std::move(parent)) {
   }
diff --git a/td/telegram/DhCache.h b/td/telegram/DhCache.h
index 1e28e0dee..3fec6bfd4 100644
--- a/td/telegram/DhCache.h
+++ b/td/telegram/DhCache.h
@@ -12,7 +12,7 @@
 
 namespace td {
 
-class DhCache : public DhCallback {
+class DhCache final : public DhCallback {
  public:
   int is_good_prime(Slice prime_str) const final;
   void add_good_prime(Slice prime_str) const final;
diff --git a/td/telegram/DialogDb.cpp b/td/telegram/DialogDb.cpp
index 4a81cac12..16bf177f2 100644
--- a/td/telegram/DialogDb.cpp
+++ b/td/telegram/DialogDb.cpp
@@ -117,7 +117,7 @@ Status drop_dialog_db(SqliteDb &db, int version) {
   return status;
 }
 
-class DialogDbImpl : public DialogDbSyncInterface {
+class DialogDbImpl final : public DialogDbSyncInterface {
  public:
   explicit DialogDbImpl(SqliteDb db) : db_(std::move(db)) {
     init().ensure();
@@ -313,7 +313,7 @@ class DialogDbImpl : public DialogDbSyncInterface {
 
 std::shared_ptr<DialogDbSyncSafeInterface> create_dialog_db_sync(
     std::shared_ptr<SqliteConnectionSafe> sqlite_connection) {
-  class DialogDbSyncSafe : public DialogDbSyncSafeInterface {
+  class DialogDbSyncSafe final : public DialogDbSyncSafeInterface {
    public:
     explicit DialogDbSyncSafe(std::shared_ptr<SqliteConnectionSafe> sqlite_connection)
         : lsls_db_([safe_connection = std::move(sqlite_connection)] {
@@ -330,7 +330,7 @@ std::shared_ptr<DialogDbSyncSafeInterface> create_dialog_db_sync(
   return std::make_shared<DialogDbSyncSafe>(std::move(sqlite_connection));
 }
 
-class DialogDbAsync : public DialogDbAsyncInterface {
+class DialogDbAsync final : public DialogDbAsyncInterface {
  public:
   DialogDbAsync(std::shared_ptr<DialogDbSyncSafeInterface> sync_db, int32 scheduler_id) {
     impl_ = create_actor_on_scheduler<Impl>("DialogDbActor", scheduler_id, std::move(sync_db));
@@ -370,7 +370,7 @@ class DialogDbAsync : public DialogDbAsyncInterface {
   }
 
  private:
-  class Impl : public Actor {
+  class Impl final : public Actor {
    public:
     explicit Impl(std::shared_ptr<DialogDbSyncSafeInterface> sync_db_safe) : sync_db_safe_(std::move(sync_db_safe)) {
     }
diff --git a/td/telegram/FileReferenceManager.h b/td/telegram/FileReferenceManager.h
index f9ad4a59a..9a5466f27 100644
--- a/td/telegram/FileReferenceManager.h
+++ b/td/telegram/FileReferenceManager.h
@@ -33,7 +33,7 @@ class Td;
 
 extern int VERBOSITY_NAME(file_references);
 
-class FileReferenceManager : public Actor {
+class FileReferenceManager final : public Actor {
  public:
   static bool is_file_reference_error(const Status &error);
   static size_t get_file_reference_error_pos(const Status &error);
diff --git a/td/telegram/Global.h b/td/telegram/Global.h
index efb4e96fc..ee4bbf17d 100644
--- a/td/telegram/Global.h
+++ b/td/telegram/Global.h
@@ -60,7 +60,7 @@ class WebPagesManager;
 
 namespace td {
 
-class Global : public ActorContext {
+class Global final : public ActorContext {
  public:
   Global();
   ~Global() final;
diff --git a/td/telegram/GroupCallManager.cpp b/td/telegram/GroupCallManager.cpp
index 3d2046118..225335adf 100644
--- a/td/telegram/GroupCallManager.cpp
+++ b/td/telegram/GroupCallManager.cpp
@@ -31,7 +31,7 @@
 
 namespace td {
 
-class GetGroupCallStreamQuery : public Td::ResultHandler {
+class GetGroupCallStreamQuery final : public Td::ResultHandler {
   Promise<string> promise_;
 
  public:
@@ -69,7 +69,7 @@ class GetGroupCallStreamQuery : public Td::ResultHandler {
   }
 };
 
-class GetGroupCallJoinAsQuery : public Td::ResultHandler {
+class GetGroupCallJoinAsQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::messageSenders>> promise_;
   DialogId dialog_id_;
 
@@ -123,7 +123,7 @@ class GetGroupCallJoinAsQuery : public Td::ResultHandler {
   }
 };
 
-class SaveDefaultGroupCallJoinAsQuery : public Td::ResultHandler {
+class SaveDefaultGroupCallJoinAsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -159,7 +159,7 @@ class SaveDefaultGroupCallJoinAsQuery : public Td::ResultHandler {
   }
 };
 
-class CreateGroupCallQuery : public Td::ResultHandler {
+class CreateGroupCallQuery final : public Td::ResultHandler {
   Promise<InputGroupCallId> promise_;
   DialogId dialog_id_;
 
@@ -218,7 +218,7 @@ class CreateGroupCallQuery : public Td::ResultHandler {
   }
 };
 
-class GetGroupCallQuery : public Td::ResultHandler {
+class GetGroupCallQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::phone_groupCall>> promise_;
 
  public:
@@ -248,7 +248,7 @@ class GetGroupCallQuery : public Td::ResultHandler {
   }
 };
 
-class GetGroupCallParticipantQuery : public Td::ResultHandler {
+class GetGroupCallParticipantQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   InputGroupCallId input_group_call_id_;
 
@@ -281,7 +281,7 @@ class GetGroupCallParticipantQuery : public Td::ResultHandler {
   }
 };
 
-class GetGroupCallParticipantsQuery : public Td::ResultHandler {
+class GetGroupCallParticipantsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   InputGroupCallId input_group_call_id_;
   string offset_;
@@ -315,7 +315,7 @@ class GetGroupCallParticipantsQuery : public Td::ResultHandler {
   }
 };
 
-class StartScheduledGroupCallQuery : public Td::ResultHandler {
+class StartScheduledGroupCallQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -347,7 +347,7 @@ class StartScheduledGroupCallQuery : public Td::ResultHandler {
   }
 };
 
-class JoinGroupCallQuery : public Td::ResultHandler {
+class JoinGroupCallQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   InputGroupCallId input_group_call_id_;
   DialogId as_dialog_id_;
@@ -406,7 +406,7 @@ class JoinGroupCallQuery : public Td::ResultHandler {
   }
 };
 
-class JoinGroupCallPresentationQuery : public Td::ResultHandler {
+class JoinGroupCallPresentationQuery final : public Td::ResultHandler {
   InputGroupCallId input_group_call_id_;
   uint64 generation_ = 0;
 
@@ -441,7 +441,7 @@ class JoinGroupCallPresentationQuery : public Td::ResultHandler {
   }
 };
 
-class LeaveGroupCallPresentationQuery : public Td::ResultHandler {
+class LeaveGroupCallPresentationQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -473,7 +473,7 @@ class LeaveGroupCallPresentationQuery : public Td::ResultHandler {
   }
 };
 
-class EditGroupCallTitleQuery : public Td::ResultHandler {
+class EditGroupCallTitleQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -505,7 +505,7 @@ class EditGroupCallTitleQuery : public Td::ResultHandler {
   }
 };
 
-class ToggleGroupCallStartSubscriptionQuery : public Td::ResultHandler {
+class ToggleGroupCallStartSubscriptionQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -537,7 +537,7 @@ class ToggleGroupCallStartSubscriptionQuery : public Td::ResultHandler {
   }
 };
 
-class ToggleGroupCallSettingsQuery : public Td::ResultHandler {
+class ToggleGroupCallSettingsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -569,7 +569,7 @@ class ToggleGroupCallSettingsQuery : public Td::ResultHandler {
   }
 };
 
-class InviteToGroupCallQuery : public Td::ResultHandler {
+class InviteToGroupCallQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -597,7 +597,7 @@ class InviteToGroupCallQuery : public Td::ResultHandler {
   }
 };
 
-class ExportGroupCallInviteQuery : public Td::ResultHandler {
+class ExportGroupCallInviteQuery final : public Td::ResultHandler {
   Promise<string> promise_;
 
  public:
@@ -628,7 +628,7 @@ class ExportGroupCallInviteQuery : public Td::ResultHandler {
   }
 };
 
-class ToggleGroupCallRecordQuery : public Td::ResultHandler {
+class ToggleGroupCallRecordQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -667,7 +667,7 @@ class ToggleGroupCallRecordQuery : public Td::ResultHandler {
   }
 };
 
-class EditGroupCallParticipantQuery : public Td::ResultHandler {
+class EditGroupCallParticipantQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -719,7 +719,7 @@ class EditGroupCallParticipantQuery : public Td::ResultHandler {
   }
 };
 
-class CheckGroupCallQuery : public Td::ResultHandler {
+class CheckGroupCallQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -755,7 +755,7 @@ class CheckGroupCallQuery : public Td::ResultHandler {
   }
 };
 
-class LeaveGroupCallQuery : public Td::ResultHandler {
+class LeaveGroupCallQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -783,7 +783,7 @@ class LeaveGroupCallQuery : public Td::ResultHandler {
   }
 };
 
-class DiscardGroupCallQuery : public Td::ResultHandler {
+class DiscardGroupCallQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
diff --git a/td/telegram/GroupCallManager.h b/td/telegram/GroupCallManager.h
index d5e10f62c..7a932bff5 100644
--- a/td/telegram/GroupCallManager.h
+++ b/td/telegram/GroupCallManager.h
@@ -29,7 +29,7 @@ namespace td {
 
 class Td;
 
-class GroupCallManager : public Actor {
+class GroupCallManager final : public Actor {
  public:
   GroupCallManager(Td *td, ActorShared<> parent);
   GroupCallManager(const GroupCallManager &) = delete;
diff --git a/td/telegram/HashtagHints.h b/td/telegram/HashtagHints.h
index e6db5dd72..e77ff3acc 100644
--- a/td/telegram/HashtagHints.h
+++ b/td/telegram/HashtagHints.h
@@ -15,7 +15,7 @@
 
 namespace td {
 
-class HashtagHints : public Actor {
+class HashtagHints final : public Actor {
  public:
   HashtagHints(string mode, ActorShared<> parent);
 
diff --git a/td/telegram/InlineQueriesManager.cpp b/td/telegram/InlineQueriesManager.cpp
index 24d9b496f..8d327886e 100644
--- a/td/telegram/InlineQueriesManager.cpp
+++ b/td/telegram/InlineQueriesManager.cpp
@@ -59,7 +59,7 @@
 
 namespace td {
 
-class GetInlineBotResultsQuery : public Td::ResultHandler {
+class GetInlineBotResultsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   UserId bot_user_id_;
@@ -116,7 +116,7 @@ class GetInlineBotResultsQuery : public Td::ResultHandler {
   }
 };
 
-class SetInlineBotResultsQuery : public Td::ResultHandler {
+class SetInlineBotResultsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
diff --git a/td/telegram/InlineQueriesManager.h b/td/telegram/InlineQueriesManager.h
index eabe1f193..5d648b7f3 100644
--- a/td/telegram/InlineQueriesManager.h
+++ b/td/telegram/InlineQueriesManager.h
@@ -35,7 +35,7 @@ class Td;
 
 class Game;
 
-class InlineQueriesManager : public Actor {
+class InlineQueriesManager final : public Actor {
  public:
   InlineQueriesManager(Td *td, ActorShared<> parent);
 
diff --git a/td/telegram/JsonValue.cpp b/td/telegram/JsonValue.cpp
index 93692ed80..bd209e908 100644
--- a/td/telegram/JsonValue.cpp
+++ b/td/telegram/JsonValue.cpp
@@ -135,7 +135,7 @@ tl_object_ptr<telegram_api::JSONValue> convert_json_value(td_api::object_ptr<td_
 
 namespace {
 
-class JsonableJsonValue : public Jsonable {
+class JsonableJsonValue final : public Jsonable {
  public:
   explicit JsonableJsonValue(const td_api::JsonValue *json_value) : json_value_(json_value) {
   }
diff --git a/td/telegram/LanguagePackManager.h b/td/telegram/LanguagePackManager.h
index 7d3543a00..6630b3cb2 100644
--- a/td/telegram/LanguagePackManager.h
+++ b/td/telegram/LanguagePackManager.h
@@ -27,7 +27,7 @@ namespace td {
 
 class SqliteKeyValue;
 
-class LanguagePackManager : public NetQueryCallback {
+class LanguagePackManager final : public NetQueryCallback {
  public:
   explicit LanguagePackManager(ActorShared<> parent) : parent_(std::move(parent)) {
   }
diff --git a/td/telegram/LinkManager.cpp b/td/telegram/LinkManager.cpp
index 7f2e25371..5d05e9880 100644
--- a/td/telegram/LinkManager.cpp
+++ b/td/telegram/LinkManager.cpp
@@ -64,13 +64,13 @@ static bool is_valid_username(Slice username) {
   return true;
 }
 
-class LinkManager::InternalLinkActiveSessions : public InternalLink {
+class LinkManager::InternalLinkActiveSessions final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeActiveSessions>();
   }
 };
 
-class LinkManager::InternalLinkAuthenticationCode : public InternalLink {
+class LinkManager::InternalLinkAuthenticationCode final : public InternalLink {
   string code_;
 
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
@@ -82,7 +82,7 @@ class LinkManager::InternalLinkAuthenticationCode : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkBackground : public InternalLink {
+class LinkManager::InternalLinkBackground final : public InternalLink {
   string background_name_;
 
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
@@ -94,7 +94,7 @@ class LinkManager::InternalLinkBackground : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkBotStart : public InternalLink {
+class LinkManager::InternalLinkBotStart final : public InternalLink {
   string bot_username_;
   string start_parameter_;
 
@@ -108,7 +108,7 @@ class LinkManager::InternalLinkBotStart : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkBotStartInGroup : public InternalLink {
+class LinkManager::InternalLinkBotStartInGroup final : public InternalLink {
   string bot_username_;
   string start_parameter_;
 
@@ -122,13 +122,13 @@ class LinkManager::InternalLinkBotStartInGroup : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkChangePhoneNumber : public InternalLink {
+class LinkManager::InternalLinkChangePhoneNumber final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeChangePhoneNumber>();
   }
 };
 
-class LinkManager::InternalLinkConfirmPhone : public InternalLink {
+class LinkManager::InternalLinkConfirmPhone final : public InternalLink {
   string hash_;
   string phone_number_;
 
@@ -142,19 +142,19 @@ class LinkManager::InternalLinkConfirmPhone : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkDialogInvite : public InternalLink {
+class LinkManager::InternalLinkDialogInvite final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeChatInvite>();
   }
 };
 
-class LinkManager::InternalLinkFilterSettings : public InternalLink {
+class LinkManager::InternalLinkFilterSettings final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeFilterSettings>();
   }
 };
 
-class LinkManager::InternalLinkGame : public InternalLink {
+class LinkManager::InternalLinkGame final : public InternalLink {
   string bot_username_;
   string game_short_name_;
 
@@ -168,7 +168,7 @@ class LinkManager::InternalLinkGame : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkLanguage : public InternalLink {
+class LinkManager::InternalLinkLanguage final : public InternalLink {
   string language_pack_id_;
 
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
@@ -180,13 +180,13 @@ class LinkManager::InternalLinkLanguage : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkMessage : public InternalLink {
+class LinkManager::InternalLinkMessage final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeMessage>();
   }
 };
 
-class LinkManager::InternalLinkMessageDraft : public InternalLink {
+class LinkManager::InternalLinkMessageDraft final : public InternalLink {
   FormattedText text_;
   bool contains_link_ = false;
 
@@ -200,7 +200,7 @@ class LinkManager::InternalLinkMessageDraft : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkPassportDataRequest : public InternalLink {
+class LinkManager::InternalLinkPassportDataRequest final : public InternalLink {
   UserId bot_user_id_;
   string scope_;
   string public_key_;
@@ -223,7 +223,7 @@ class LinkManager::InternalLinkPassportDataRequest : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkProxy : public InternalLink {
+class LinkManager::InternalLinkProxy final : public InternalLink {
   string server_;
   int32 port_;
   td_api::object_ptr<td_api::ProxyType> type_;
@@ -254,7 +254,7 @@ class LinkManager::InternalLinkProxy : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkPublicDialog : public InternalLink {
+class LinkManager::InternalLinkPublicDialog final : public InternalLink {
   string dialog_username_;
 
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
@@ -266,19 +266,19 @@ class LinkManager::InternalLinkPublicDialog : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkQrCodeAuthentication : public InternalLink {
+class LinkManager::InternalLinkQrCodeAuthentication final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeQrCodeAuthentication>();
   }
 };
 
-class LinkManager::InternalLinkSettings : public InternalLink {
+class LinkManager::InternalLinkSettings final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeSettings>();
   }
 };
 
-class LinkManager::InternalLinkStickerSet : public InternalLink {
+class LinkManager::InternalLinkStickerSet final : public InternalLink {
   string sticker_set_name_;
 
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
@@ -290,7 +290,7 @@ class LinkManager::InternalLinkStickerSet : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkTheme : public InternalLink {
+class LinkManager::InternalLinkTheme final : public InternalLink {
   string theme_name_;
 
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
@@ -302,19 +302,19 @@ class LinkManager::InternalLinkTheme : public InternalLink {
   }
 };
 
-class LinkManager::InternalLinkThemeSettings : public InternalLink {
+class LinkManager::InternalLinkThemeSettings final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeThemeSettings>();
   }
 };
 
-class LinkManager::InternalLinkUnknownDeepLink : public InternalLink {
+class LinkManager::InternalLinkUnknownDeepLink final : public InternalLink {
   td_api::object_ptr<td_api::InternalLinkType> get_internal_link_type_object() const final {
     return td_api::make_object<td_api::internalLinkTypeUnknownDeepLink>();
   }
 };
 
-class LinkManager::InternalLinkVoiceChat : public InternalLink {
+class LinkManager::InternalLinkVoiceChat final : public InternalLink {
   string dialog_username_;
   string invite_hash_;
 
@@ -328,7 +328,7 @@ class LinkManager::InternalLinkVoiceChat : public InternalLink {
   }
 };
 
-class RequestUrlAuthQuery : public Td::ResultHandler {
+class RequestUrlAuthQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::LoginUrlInfo>> promise_;
   string url_;
   DialogId dialog_id_;
@@ -398,7 +398,7 @@ class RequestUrlAuthQuery : public Td::ResultHandler {
   }
 };
 
-class AcceptUrlAuthQuery : public Td::ResultHandler {
+class AcceptUrlAuthQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::httpUrl>> promise_;
   string url_;
   DialogId dialog_id_;
diff --git a/td/telegram/LinkManager.h b/td/telegram/LinkManager.h
index 7aaf23a48..8ae0cccc5 100644
--- a/td/telegram/LinkManager.h
+++ b/td/telegram/LinkManager.h
@@ -23,7 +23,7 @@ namespace td {
 
 class Td;
 
-class LinkManager : public Actor {
+class LinkManager final : public Actor {
  public:
   LinkManager(Td *td, ActorShared<> parent);
 
diff --git a/td/telegram/MessageContent.cpp b/td/telegram/MessageContent.cpp
index c95a6e9dc..3aac32f07 100644
--- a/td/telegram/MessageContent.cpp
+++ b/td/telegram/MessageContent.cpp
@@ -88,7 +88,7 @@
 
 namespace td {
 
-class MessageText : public MessageContent {
+class MessageText final : public MessageContent {
  public:
   FormattedText text;
   WebPageId web_page_id;
@@ -102,7 +102,7 @@ class MessageText : public MessageContent {
   }
 };
 
-class MessageAnimation : public MessageContent {
+class MessageAnimation final : public MessageContent {
  public:
   FileId file_id;
 
@@ -117,7 +117,7 @@ class MessageAnimation : public MessageContent {
   }
 };
 
-class MessageAudio : public MessageContent {
+class MessageAudio final : public MessageContent {
  public:
   FileId file_id;
 
@@ -132,7 +132,7 @@ class MessageAudio : public MessageContent {
   }
 };
 
-class MessageDocument : public MessageContent {
+class MessageDocument final : public MessageContent {
  public:
   FileId file_id;
 
@@ -147,7 +147,7 @@ class MessageDocument : public MessageContent {
   }
 };
 
-class MessagePhoto : public MessageContent {
+class MessagePhoto final : public MessageContent {
  public:
   Photo photo;
 
@@ -162,7 +162,7 @@ class MessagePhoto : public MessageContent {
   }
 };
 
-class MessageSticker : public MessageContent {
+class MessageSticker final : public MessageContent {
  public:
   FileId file_id;
 
@@ -175,7 +175,7 @@ class MessageSticker : public MessageContent {
   }
 };
 
-class MessageVideo : public MessageContent {
+class MessageVideo final : public MessageContent {
  public:
   FileId file_id;
 
@@ -190,7 +190,7 @@ class MessageVideo : public MessageContent {
   }
 };
 
-class MessageVoiceNote : public MessageContent {
+class MessageVoiceNote final : public MessageContent {
  public:
   FileId file_id;
 
@@ -207,7 +207,7 @@ class MessageVoiceNote : public MessageContent {
   }
 };
 
-class MessageContact : public MessageContent {
+class MessageContact final : public MessageContent {
  public:
   Contact contact;
 
@@ -220,7 +220,7 @@ class MessageContact : public MessageContent {
   }
 };
 
-class MessageLocation : public MessageContent {
+class MessageLocation final : public MessageContent {
  public:
   Location location;
 
@@ -233,7 +233,7 @@ class MessageLocation : public MessageContent {
   }
 };
 
-class MessageVenue : public MessageContent {
+class MessageVenue final : public MessageContent {
  public:
   Venue venue;
 
@@ -246,7 +246,7 @@ class MessageVenue : public MessageContent {
   }
 };
 
-class MessageChatCreate : public MessageContent {
+class MessageChatCreate final : public MessageContent {
  public:
   string title;
   vector<UserId> participant_user_ids;
@@ -261,7 +261,7 @@ class MessageChatCreate : public MessageContent {
   }
 };
 
-class MessageChatChangeTitle : public MessageContent {
+class MessageChatChangeTitle final : public MessageContent {
  public:
   string title;
 
@@ -274,7 +274,7 @@ class MessageChatChangeTitle : public MessageContent {
   }
 };
 
-class MessageChatChangePhoto : public MessageContent {
+class MessageChatChangePhoto final : public MessageContent {
  public:
   Photo photo;
 
@@ -287,21 +287,21 @@ class MessageChatChangePhoto : public MessageContent {
   }
 };
 
-class MessageChatDeletePhoto : public MessageContent {
+class MessageChatDeletePhoto final : public MessageContent {
  public:
   MessageContentType get_type() const final {
     return MessageContentType::ChatDeletePhoto;
   }
 };
 
-class MessageChatDeleteHistory : public MessageContent {
+class MessageChatDeleteHistory final : public MessageContent {
  public:
   MessageContentType get_type() const final {
     return MessageContentType::ChatDeleteHistory;
   }
 };
 
-class MessageChatAddUsers : public MessageContent {
+class MessageChatAddUsers final : public MessageContent {
  public:
   vector<UserId> user_ids;
 
@@ -314,14 +314,14 @@ class MessageChatAddUsers : public MessageContent {
   }
 };
 
-class MessageChatJoinedByLink : public MessageContent {
+class MessageChatJoinedByLink final : public MessageContent {
  public:
   MessageContentType get_type() const final {
     return MessageContentType::ChatJoinedByLink;
   }
 };
 
-class MessageChatDeleteUser : public MessageContent {
+class MessageChatDeleteUser final : public MessageContent {
  public:
   UserId user_id;
 
@@ -334,7 +334,7 @@ class MessageChatDeleteUser : public MessageContent {
   }
 };
 
-class MessageChatMigrateTo : public MessageContent {
+class MessageChatMigrateTo final : public MessageContent {
  public:
   ChannelId migrated_to_channel_id;
 
@@ -347,7 +347,7 @@ class MessageChatMigrateTo : public MessageContent {
   }
 };
 
-class MessageChannelCreate : public MessageContent {
+class MessageChannelCreate final : public MessageContent {
  public:
   string title;
 
@@ -360,7 +360,7 @@ class MessageChannelCreate : public MessageContent {
   }
 };
 
-class MessageChannelMigrateFrom : public MessageContent {
+class MessageChannelMigrateFrom final : public MessageContent {
  public:
   string title;
   ChatId migrated_from_chat_id;
@@ -375,7 +375,7 @@ class MessageChannelMigrateFrom : public MessageContent {
   }
 };
 
-class MessagePinMessage : public MessageContent {
+class MessagePinMessage final : public MessageContent {
  public:
   MessageId message_id;
 
@@ -388,7 +388,7 @@ class MessagePinMessage : public MessageContent {
   }
 };
 
-class MessageGame : public MessageContent {
+class MessageGame final : public MessageContent {
  public:
   Game game;
 
@@ -401,7 +401,7 @@ class MessageGame : public MessageContent {
   }
 };
 
-class MessageGameScore : public MessageContent {
+class MessageGameScore final : public MessageContent {
  public:
   MessageId game_message_id;
   int64 game_id;
@@ -417,14 +417,14 @@ class MessageGameScore : public MessageContent {
   }
 };
 
-class MessageScreenshotTaken : public MessageContent {
+class MessageScreenshotTaken final : public MessageContent {
  public:
   MessageContentType get_type() const final {
     return MessageContentType::ScreenshotTaken;
   }
 };
 
-class MessageChatSetTtl : public MessageContent {
+class MessageChatSetTtl final : public MessageContent {
  public:
   int32 ttl;
 
@@ -437,7 +437,7 @@ class MessageChatSetTtl : public MessageContent {
   }
 };
 
-class MessageUnsupported : public MessageContent {
+class MessageUnsupported final : public MessageContent {
  public:
   static constexpr int32 CURRENT_VERSION = 7;
   int32 version = CURRENT_VERSION;
@@ -451,7 +451,7 @@ class MessageUnsupported : public MessageContent {
   }
 };
 
-class MessageCall : public MessageContent {
+class MessageCall final : public MessageContent {
  public:
   int64 call_id;
   int32 duration;
@@ -468,7 +468,7 @@ class MessageCall : public MessageContent {
   }
 };
 
-class MessageInvoice : public MessageContent {
+class MessageInvoice final : public MessageContent {
  public:
   InputInvoice input_invoice;
 
@@ -481,7 +481,7 @@ class MessageInvoice : public MessageContent {
   }
 };
 
-class MessagePaymentSuccessful : public MessageContent {
+class MessagePaymentSuccessful final : public MessageContent {
  public:
   DialogId invoice_dialog_id;
   MessageId invoice_message_id;
@@ -509,7 +509,7 @@ class MessagePaymentSuccessful : public MessageContent {
   }
 };
 
-class MessageVideoNote : public MessageContent {
+class MessageVideoNote final : public MessageContent {
  public:
   FileId file_id;
 
@@ -524,14 +524,14 @@ class MessageVideoNote : public MessageContent {
   }
 };
 
-class MessageContactRegistered : public MessageContent {
+class MessageContactRegistered final : public MessageContent {
  public:
   MessageContentType get_type() const final {
     return MessageContentType::ContactRegistered;
   }
 };
 
-class MessageExpiredPhoto : public MessageContent {
+class MessageExpiredPhoto final : public MessageContent {
  public:
   MessageExpiredPhoto() = default;
 
@@ -540,7 +540,7 @@ class MessageExpiredPhoto : public MessageContent {
   }
 };
 
-class MessageExpiredVideo : public MessageContent {
+class MessageExpiredVideo final : public MessageContent {
  public:
   MessageExpiredVideo() = default;
 
@@ -549,7 +549,7 @@ class MessageExpiredVideo : public MessageContent {
   }
 };
 
-class MessageLiveLocation : public MessageContent {
+class MessageLiveLocation final : public MessageContent {
  public:
   Location location;
   int32 period = 0;
@@ -579,7 +579,7 @@ class MessageLiveLocation : public MessageContent {
   }
 };
 
-class MessageCustomServiceAction : public MessageContent {
+class MessageCustomServiceAction final : public MessageContent {
  public:
   string message;
 
@@ -592,7 +592,7 @@ class MessageCustomServiceAction : public MessageContent {
   }
 };
 
-class MessageWebsiteConnected : public MessageContent {
+class MessageWebsiteConnected final : public MessageContent {
  public:
   string domain_name;
 
@@ -605,7 +605,7 @@ class MessageWebsiteConnected : public MessageContent {
   }
 };
 
-class MessagePassportDataSent : public MessageContent {
+class MessagePassportDataSent final : public MessageContent {
  public:
   vector<SecureValueType> types;
 
@@ -618,7 +618,7 @@ class MessagePassportDataSent : public MessageContent {
   }
 };
 
-class MessagePassportDataReceived : public MessageContent {
+class MessagePassportDataReceived final : public MessageContent {
  public:
   vector<EncryptedSecureValue> values;
   EncryptedSecureCredentials credentials;
@@ -633,7 +633,7 @@ class MessagePassportDataReceived : public MessageContent {
   }
 };
 
-class MessagePoll : public MessageContent {
+class MessagePoll final : public MessageContent {
  public:
   PollId poll_id;
 
@@ -646,7 +646,7 @@ class MessagePoll : public MessageContent {
   }
 };
 
-class MessageDice : public MessageContent {
+class MessageDice final : public MessageContent {
  public:
   string emoji;
   int32 dice_value = 0;
@@ -676,7 +676,7 @@ class MessageDice : public MessageContent {
 
 constexpr const char *MessageDice::DEFAULT_EMOJI;
 
-class MessageProximityAlertTriggered : public MessageContent {
+class MessageProximityAlertTriggered final : public MessageContent {
  public:
   DialogId traveler_dialog_id;
   DialogId watcher_dialog_id;
@@ -692,7 +692,7 @@ class MessageProximityAlertTriggered : public MessageContent {
   }
 };
 
-class MessageGroupCall : public MessageContent {
+class MessageGroupCall final : public MessageContent {
  public:
   InputGroupCallId input_group_call_id;
   int32 duration = -1;
@@ -708,7 +708,7 @@ class MessageGroupCall : public MessageContent {
   }
 };
 
-class MessageInviteToGroupCall : public MessageContent {
+class MessageInviteToGroupCall final : public MessageContent {
  public:
   InputGroupCallId input_group_call_id;
   vector<UserId> user_ids;
diff --git a/td/telegram/MessagesDb.cpp b/td/telegram/MessagesDb.cpp
index 1cd2a5853..1c67f58ce 100644
--- a/td/telegram/MessagesDb.cpp
+++ b/td/telegram/MessagesDb.cpp
@@ -177,7 +177,7 @@ Status drop_messages_db(SqliteDb &db, int32 version) {
   return db.exec("DROP TABLE IF EXISTS messages");
 }
 
-class MessagesDbImpl : public MessagesDbSyncInterface {
+class MessagesDbImpl final : public MessagesDbSyncInterface {
  public:
   explicit MessagesDbImpl(SqliteDb db) : db_(std::move(db)) {
     init().ensure();
@@ -925,7 +925,7 @@ class MessagesDbImpl : public MessagesDbSyncInterface {
 
 std::shared_ptr<MessagesDbSyncSafeInterface> create_messages_db_sync(
     std::shared_ptr<SqliteConnectionSafe> sqlite_connection) {
-  class MessagesDbSyncSafe : public MessagesDbSyncSafeInterface {
+  class MessagesDbSyncSafe final : public MessagesDbSyncSafeInterface {
    public:
     explicit MessagesDbSyncSafe(std::shared_ptr<SqliteConnectionSafe> sqlite_connection)
         : lsls_db_([safe_connection = std::move(sqlite_connection)] {
@@ -942,7 +942,7 @@ std::shared_ptr<MessagesDbSyncSafeInterface> create_messages_db_sync(
   return std::make_shared<MessagesDbSyncSafe>(std::move(sqlite_connection));
 }
 
-class MessagesDbAsync : public MessagesDbAsyncInterface {
+class MessagesDbAsync final : public MessagesDbAsyncInterface {
  public:
   MessagesDbAsync(std::shared_ptr<MessagesDbSyncSafeInterface> sync_db, int32 scheduler_id) {
     impl_ = create_actor_on_scheduler<Impl>("MessagesDbActor", scheduler_id, std::move(sync_db));
@@ -1017,7 +1017,7 @@ class MessagesDbAsync : public MessagesDbAsyncInterface {
   }
 
  private:
-  class Impl : public Actor {
+  class Impl final : public Actor {
    public:
     explicit Impl(std::shared_ptr<MessagesDbSyncSafeInterface> sync_db_safe) : sync_db_safe_(std::move(sync_db_safe)) {
     }
diff --git a/td/telegram/MessagesManager.cpp b/td/telegram/MessagesManager.cpp
index d72356fcf..9b8f825d6 100644
--- a/td/telegram/MessagesManager.cpp
+++ b/td/telegram/MessagesManager.cpp
@@ -84,7 +84,7 @@
 
 namespace td {
 
-class GetDialogFiltersQuery : public Td::ResultHandler {
+class GetDialogFiltersQuery final : public Td::ResultHandler {
   Promise<vector<tl_object_ptr<telegram_api::dialogFilter>>> promise_;
 
  public:
@@ -110,7 +110,7 @@ class GetDialogFiltersQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateDialogFilterQuery : public Td::ResultHandler {
+class UpdateDialogFilterQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -142,7 +142,7 @@ class UpdateDialogFilterQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateDialogFiltersOrderQuery : public Td::ResultHandler {
+class UpdateDialogFiltersOrderQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -169,7 +169,7 @@ class UpdateDialogFiltersOrderQuery : public Td::ResultHandler {
   }
 };
 
-class GetSuggestedDialogFiltersQuery : public Td::ResultHandler {
+class GetSuggestedDialogFiltersQuery final : public Td::ResultHandler {
   Promise<vector<tl_object_ptr<telegram_api::dialogFilterSuggested>>> promise_;
 
  public:
@@ -195,7 +195,7 @@ class GetSuggestedDialogFiltersQuery : public Td::ResultHandler {
   }
 };
 
-class GetOnlinesQuery : public Td::ResultHandler {
+class GetOnlinesQuery final : public Td::ResultHandler {
   DialogId dialog_id_;
 
  public:
@@ -226,7 +226,7 @@ class GetOnlinesQuery : public Td::ResultHandler {
   }
 };
 
-class GetAllDraftsQuery : public Td::ResultHandler {
+class GetAllDraftsQuery final : public Td::ResultHandler {
  public:
   void send() {
     send_query(G()->net_query_creator().create(telegram_api::messages_getAllDrafts()));
@@ -251,7 +251,7 @@ class GetAllDraftsQuery : public Td::ResultHandler {
   }
 };
 
-class GetDialogQuery : public Td::ResultHandler {
+class GetDialogQuery final : public Td::ResultHandler {
   DialogId dialog_id_;
 
  public:
@@ -293,7 +293,7 @@ class GetDialogQuery : public Td::ResultHandler {
   }
 };
 
-class GetDialogsQuery : public Td::ResultHandler {
+class GetDialogsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -329,7 +329,7 @@ class GetDialogsQuery : public Td::ResultHandler {
   }
 };
 
-class GetPinnedDialogsActor : public NetActorOnce {
+class GetPinnedDialogsActor final : public NetActorOnce {
   FolderId folder_id_;
   Promise<Unit> promise_;
 
@@ -366,7 +366,7 @@ class GetPinnedDialogsActor : public NetActorOnce {
   }
 };
 
-class GetDialogUnreadMarksQuery : public Td::ResultHandler {
+class GetDialogUnreadMarksQuery final : public Td::ResultHandler {
  public:
   void send() {
     send_query(G()->net_query_creator().create(telegram_api::messages_getDialogUnreadMarks()));
@@ -394,7 +394,7 @@ class GetDialogUnreadMarksQuery : public Td::ResultHandler {
   }
 };
 
-class GetDiscussionMessageQuery : public Td::ResultHandler {
+class GetDiscussionMessageQuery final : public Td::ResultHandler {
   Promise<vector<FullMessageId>> promise_;
   DialogId dialog_id_;
   MessageId message_id_;
@@ -435,7 +435,7 @@ class GetDiscussionMessageQuery : public Td::ResultHandler {
   }
 };
 
-class GetMessagesQuery : public Td::ResultHandler {
+class GetMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -469,7 +469,7 @@ class GetMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class GetChannelMessagesQuery : public Td::ResultHandler {
+class GetChannelMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -530,7 +530,7 @@ class GetChannelMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class GetScheduledMessagesQuery : public Td::ResultHandler {
+class GetScheduledMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -570,7 +570,7 @@ class GetScheduledMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateDialogPinnedMessageQuery : public Td::ResultHandler {
+class UpdateDialogPinnedMessageQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -618,7 +618,7 @@ class UpdateDialogPinnedMessageQuery : public Td::ResultHandler {
   }
 };
 
-class UnpinAllMessagesQuery : public Td::ResultHandler {
+class UnpinAllMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -679,7 +679,7 @@ class UnpinAllMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class ExportChannelMessageLinkQuery : public Td::ResultHandler {
+class ExportChannelMessageLinkQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   MessageId message_id_;
@@ -730,7 +730,7 @@ class ExportChannelMessageLinkQuery : public Td::ResultHandler {
   }
 };
 
-class GetDialogListActor : public NetActorOnce {
+class GetDialogListActor final : public NetActorOnce {
   FolderId folder_id_;
   Promise<Unit> promise_;
 
@@ -792,7 +792,7 @@ class GetDialogListActor : public NetActorOnce {
   }
 };
 
-class SearchPublicDialogsQuery : public Td::ResultHandler {
+class SearchPublicDialogsQuery final : public Td::ResultHandler {
   string query_;
 
  public:
@@ -823,7 +823,7 @@ class SearchPublicDialogsQuery : public Td::ResultHandler {
   }
 };
 
-class GetCommonDialogsQuery : public Td::ResultHandler {
+class GetCommonDialogsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   UserId user_id_;
   int32 offset_chat_id_ = 0;
@@ -877,7 +877,7 @@ class GetCommonDialogsQuery : public Td::ResultHandler {
   }
 };
 
-class GetBlockedDialogsQuery : public Td::ResultHandler {
+class GetBlockedDialogsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int32 offset_;
   int32 limit_;
@@ -937,7 +937,7 @@ class GetBlockedDialogsQuery : public Td::ResultHandler {
   }
 };
 
-class CreateChatQuery : public Td::ResultHandler {
+class CreateChatQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int64 random_id_;
 
@@ -967,7 +967,7 @@ class CreateChatQuery : public Td::ResultHandler {
   }
 };
 
-class CreateChannelQuery : public Td::ResultHandler {
+class CreateChannelQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int64 random_id_;
 
@@ -1013,7 +1013,7 @@ class CreateChannelQuery : public Td::ResultHandler {
   }
 };
 
-class CheckHistoryImportQuery : public Td::ResultHandler {
+class CheckHistoryImportQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::MessageFileType>> promise_;
 
  public:
@@ -1050,7 +1050,7 @@ class CheckHistoryImportQuery : public Td::ResultHandler {
   }
 };
 
-class CheckHistoryImportPeerQuery : public Td::ResultHandler {
+class CheckHistoryImportPeerQuery final : public Td::ResultHandler {
   Promise<string> promise_;
   DialogId dialog_id_;
 
@@ -1082,7 +1082,7 @@ class CheckHistoryImportPeerQuery : public Td::ResultHandler {
   }
 };
 
-class InitHistoryImportQuery : public Td::ResultHandler {
+class InitHistoryImportQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   FileId file_id_;
   DialogId dialog_id_;
@@ -1133,7 +1133,7 @@ class InitHistoryImportQuery : public Td::ResultHandler {
   }
 };
 
-class UploadImportedMediaQuery : public Td::ResultHandler {
+class UploadImportedMediaQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   int64 import_id_;
@@ -1186,7 +1186,7 @@ class UploadImportedMediaQuery : public Td::ResultHandler {
   }
 };
 
-class StartImportHistoryQuery : public Td::ResultHandler {
+class StartImportHistoryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -1222,7 +1222,7 @@ class StartImportHistoryQuery : public Td::ResultHandler {
   }
 };
 
-class EditDialogPhotoQuery : public Td::ResultHandler {
+class EditDialogPhotoQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   FileId file_id_;
   bool was_uploaded_ = false;
@@ -1306,7 +1306,7 @@ class EditDialogPhotoQuery : public Td::ResultHandler {
   }
 };
 
-class EditDialogTitleQuery : public Td::ResultHandler {
+class EditDialogTitleQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -1362,7 +1362,7 @@ class EditDialogTitleQuery : public Td::ResultHandler {
   }
 };
 
-class SetHistoryTtlQuery : public Td::ResultHandler {
+class SetHistoryTtlQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -1403,7 +1403,7 @@ class SetHistoryTtlQuery : public Td::ResultHandler {
   }
 };
 
-class EditChatDefaultBannedRightsQuery : public Td::ResultHandler {
+class EditChatDefaultBannedRightsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -1443,7 +1443,7 @@ class EditChatDefaultBannedRightsQuery : public Td::ResultHandler {
   }
 };
 
-class SaveDraftMessageQuery : public Td::ResultHandler {
+class SaveDraftMessageQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -1507,7 +1507,7 @@ class SaveDraftMessageQuery : public Td::ResultHandler {
   }
 };
 
-class ClearAllDraftsQuery : public Td::ResultHandler {
+class ClearAllDraftsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -1542,7 +1542,7 @@ class ClearAllDraftsQuery : public Td::ResultHandler {
   }
 };
 
-class ToggleDialogPinQuery : public Td::ResultHandler {
+class ToggleDialogPinQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   bool is_pinned_;
@@ -1592,7 +1592,7 @@ class ToggleDialogPinQuery : public Td::ResultHandler {
   }
 };
 
-class ReorderPinnedDialogsQuery : public Td::ResultHandler {
+class ReorderPinnedDialogsQuery final : public Td::ResultHandler {
   FolderId folder_id_;
   Promise<Unit> promise_;
 
@@ -1632,7 +1632,7 @@ class ReorderPinnedDialogsQuery : public Td::ResultHandler {
   }
 };
 
-class ToggleDialogUnreadMarkQuery : public Td::ResultHandler {
+class ToggleDialogUnreadMarkQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   bool is_marked_as_unread_;
@@ -1683,7 +1683,7 @@ class ToggleDialogUnreadMarkQuery : public Td::ResultHandler {
   }
 };
 
-class ToggleDialogIsBlockedQuery : public Td::ResultHandler {
+class ToggleDialogIsBlockedQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   bool is_blocked_;
@@ -1732,7 +1732,7 @@ class ToggleDialogIsBlockedQuery : public Td::ResultHandler {
   }
 };
 
-class GetMessagesViewsQuery : public Td::ResultHandler {
+class GetMessagesViewsQuery final : public Td::ResultHandler {
   DialogId dialog_id_;
   vector<MessageId> message_ids_;
 
@@ -1785,7 +1785,7 @@ class GetMessagesViewsQuery : public Td::ResultHandler {
   }
 };
 
-class ReadMessagesContentsQuery : public Td::ResultHandler {
+class ReadMessagesContentsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -1825,7 +1825,7 @@ class ReadMessagesContentsQuery : public Td::ResultHandler {
   }
 };
 
-class ReadChannelMessagesContentsQuery : public Td::ResultHandler {
+class ReadChannelMessagesContentsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -1869,7 +1869,7 @@ class ReadChannelMessagesContentsQuery : public Td::ResultHandler {
   }
 };
 
-class GetDialogMessageByDateQuery : public Td::ResultHandler {
+class GetDialogMessageByDateQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   int32 date_;
@@ -1924,7 +1924,7 @@ class GetDialogMessageByDateQuery : public Td::ResultHandler {
   }
 };
 
-class GetHistoryQuery : public Td::ResultHandler {
+class GetHistoryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   MessageId from_message_id_;
@@ -2000,7 +2000,7 @@ class GetHistoryQuery : public Td::ResultHandler {
   }
 };
 
-class ReadHistoryQuery : public Td::ResultHandler {
+class ReadHistoryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -2043,7 +2043,7 @@ class ReadHistoryQuery : public Td::ResultHandler {
   }
 };
 
-class ReadChannelHistoryQuery : public Td::ResultHandler {
+class ReadChannelHistoryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
 
@@ -2077,7 +2077,7 @@ class ReadChannelHistoryQuery : public Td::ResultHandler {
   }
 };
 
-class ReadDiscussionQuery : public Td::ResultHandler {
+class ReadDiscussionQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -2109,7 +2109,7 @@ class ReadDiscussionQuery : public Td::ResultHandler {
   }
 };
 
-class SearchMessagesQuery : public Td::ResultHandler {
+class SearchMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   string query_;
@@ -2218,7 +2218,7 @@ class SearchMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class SearchMessagesGlobalQuery : public Td::ResultHandler {
+class SearchMessagesGlobalQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   string query_;
   int32 offset_date_;
@@ -2279,7 +2279,7 @@ class SearchMessagesGlobalQuery : public Td::ResultHandler {
   }
 };
 
-class GetAllScheduledMessagesQuery : public Td::ResultHandler {
+class GetAllScheduledMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   uint32 generation_;
@@ -2321,7 +2321,7 @@ class GetAllScheduledMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class GetRecentLocationsQuery : public Td::ResultHandler {
+class GetRecentLocationsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   int32 limit_;
@@ -2375,7 +2375,7 @@ class GetRecentLocationsQuery : public Td::ResultHandler {
   }
 };
 
-class GetMessagePublicForwardsQuery : public Td::ResultHandler {
+class GetMessagePublicForwardsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   int32 limit_;
@@ -2420,7 +2420,7 @@ class GetMessagePublicForwardsQuery : public Td::ResultHandler {
   }
 };
 
-class HidePromoDataQuery : public Td::ResultHandler {
+class HidePromoDataQuery final : public Td::ResultHandler {
   DialogId dialog_id_;
 
  public:
@@ -2447,7 +2447,7 @@ class HidePromoDataQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteHistoryQuery : public Td::ResultHandler {
+class DeleteHistoryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   MessageId max_message_id_;
@@ -2516,7 +2516,7 @@ class DeleteHistoryQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteChannelHistoryQuery : public Td::ResultHandler {
+class DeleteChannelHistoryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   MessageId max_message_id_;
@@ -2558,7 +2558,7 @@ class DeleteChannelHistoryQuery : public Td::ResultHandler {
   }
 };
 
-class DeletePhoneCallHistoryQuery : public Td::ResultHandler {
+class DeletePhoneCallHistoryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   bool revoke_;
 
@@ -2613,7 +2613,7 @@ class DeletePhoneCallHistoryQuery : public Td::ResultHandler {
   }
 };
 
-class BlockFromRepliesQuery : public Td::ResultHandler {
+class BlockFromRepliesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -2651,7 +2651,7 @@ class BlockFromRepliesQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteUserHistoryQuery : public Td::ResultHandler {
+class DeleteUserHistoryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   UserId user_id_;
@@ -2712,7 +2712,7 @@ class DeleteUserHistoryQuery : public Td::ResultHandler {
   }
 };
 
-class ReadMentionsQuery : public Td::ResultHandler {
+class ReadMentionsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -2772,7 +2772,7 @@ class ReadMentionsQuery : public Td::ResultHandler {
   }
 };
 
-class SendSecretMessageActor : public NetActor {
+class SendSecretMessageActor final : public NetActor {
   int64 random_id_;
 
  public:
@@ -2822,7 +2822,7 @@ class SendSecretMessageActor : public NetActor {
   }
 };
 
-class SendMessageActor : public NetActorOnce {
+class SendMessageActor final : public NetActorOnce {
   int64 random_id_;
   DialogId dialog_id_;
 
@@ -2907,7 +2907,7 @@ class SendMessageActor : public NetActorOnce {
   }
 };
 
-class StartBotQuery : public Td::ResultHandler {
+class StartBotQuery final : public Td::ResultHandler {
   int64 random_id_;
   DialogId dialog_id_;
 
@@ -2957,7 +2957,7 @@ class StartBotQuery : public Td::ResultHandler {
   }
 };
 
-class SendInlineBotResultQuery : public Td::ResultHandler {
+class SendInlineBotResultQuery final : public Td::ResultHandler {
   int64 random_id_;
   DialogId dialog_id_;
 
@@ -3001,7 +3001,7 @@ class SendInlineBotResultQuery : public Td::ResultHandler {
   }
 };
 
-class SendMultiMediaActor : public NetActorOnce {
+class SendMultiMediaActor final : public NetActorOnce {
   vector<FileId> file_ids_;
   vector<string> file_references_;
   vector<int64> random_ids_;
@@ -3107,7 +3107,7 @@ class SendMultiMediaActor : public NetActorOnce {
   }
 };
 
-class SendMediaActor : public NetActorOnce {
+class SendMediaActor final : public NetActorOnce {
   int64 random_id_ = 0;
   FileId file_id_;
   FileId thumbnail_file_id_;
@@ -3216,7 +3216,7 @@ class SendMediaActor : public NetActorOnce {
   }
 };
 
-class UploadMediaQuery : public Td::ResultHandler {
+class UploadMediaQuery final : public Td::ResultHandler {
   DialogId dialog_id_;
   MessageId message_id_;
   FileId file_id_;
@@ -3295,7 +3295,7 @@ class UploadMediaQuery : public Td::ResultHandler {
   }
 };
 
-class SendScheduledMessageActor : public NetActorOnce {
+class SendScheduledMessageActor final : public NetActorOnce {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -3342,7 +3342,7 @@ class SendScheduledMessageActor : public NetActorOnce {
   }
 };
 
-class EditMessageActor : public NetActorOnce {
+class EditMessageActor final : public NetActorOnce {
   Promise<int32> promise_;
   DialogId dialog_id_;
 
@@ -3431,7 +3431,7 @@ class EditMessageActor : public NetActorOnce {
   }
 };
 
-class EditInlineMessageQuery : public Td::ResultHandler {
+class EditInlineMessageQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -3487,7 +3487,7 @@ class EditInlineMessageQuery : public Td::ResultHandler {
   }
 };
 
-class SetGameScoreActor : public NetActorOnce {
+class SetGameScoreActor final : public NetActorOnce {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -3544,7 +3544,7 @@ class SetGameScoreActor : public NetActorOnce {
   }
 };
 
-class SetInlineGameScoreQuery : public Td::ResultHandler {
+class SetInlineGameScoreQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -3589,7 +3589,7 @@ class SetInlineGameScoreQuery : public Td::ResultHandler {
   }
 };
 
-class GetGameHighScoresQuery : public Td::ResultHandler {
+class GetGameHighScoresQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   int64 random_id_;
@@ -3629,7 +3629,7 @@ class GetGameHighScoresQuery : public Td::ResultHandler {
   }
 };
 
-class GetInlineGameHighScoresQuery : public Td::ResultHandler {
+class GetInlineGameHighScoresQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int64 random_id_;
 
@@ -3667,7 +3667,7 @@ class GetInlineGameHighScoresQuery : public Td::ResultHandler {
   }
 };
 
-class ForwardMessagesActor : public NetActorOnce {
+class ForwardMessagesActor final : public NetActorOnce {
   Promise<Unit> promise_;
   vector<int64> random_ids_;
   DialogId to_dialog_id_;
@@ -3773,7 +3773,7 @@ class ForwardMessagesActor : public NetActorOnce {
   }
 };
 
-class SendScreenshotNotificationQuery : public Td::ResultHandler {
+class SendScreenshotNotificationQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int64 random_id_;
   DialogId dialog_id_;
@@ -3819,7 +3819,7 @@ class SendScreenshotNotificationQuery : public Td::ResultHandler {
   }
 };
 
-class SetTypingQuery : public Td::ResultHandler {
+class SetTypingQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -3866,7 +3866,7 @@ class SetTypingQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteMessagesQuery : public Td::ResultHandler {
+class DeleteMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   int32 query_count_;
@@ -3929,7 +3929,7 @@ class DeleteMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteChannelMessagesQuery : public Td::ResultHandler {
+class DeleteChannelMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int32 query_count_;
   ChannelId channel_id_;
@@ -3988,7 +3988,7 @@ class DeleteChannelMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteScheduledMessagesQuery : public Td::ResultHandler {
+class DeleteScheduledMessagesQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -4027,7 +4027,7 @@ class DeleteScheduledMessagesQuery : public Td::ResultHandler {
   }
 };
 
-class GetDialogNotifySettingsQuery : public Td::ResultHandler {
+class GetDialogNotifySettingsQuery final : public Td::ResultHandler {
   DialogId dialog_id_;
 
  public:
@@ -4055,7 +4055,7 @@ class GetDialogNotifySettingsQuery : public Td::ResultHandler {
   }
 };
 
-class GetNotifySettingsExceptionsQuery : public Td::ResultHandler {
+class GetNotifySettingsExceptionsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -4117,7 +4117,7 @@ class GetNotifySettingsExceptionsQuery : public Td::ResultHandler {
   }
 };
 
-class GetScopeNotifySettingsQuery : public Td::ResultHandler {
+class GetScopeNotifySettingsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   NotificationSettingsScope scope_;
 
@@ -4149,7 +4149,7 @@ class GetScopeNotifySettingsQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateDialogNotifySettingsQuery : public Td::ResultHandler {
+class UpdateDialogNotifySettingsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -4212,7 +4212,7 @@ class UpdateDialogNotifySettingsQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateScopeNotifySettingsQuery : public Td::ResultHandler {
+class UpdateScopeNotifySettingsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   NotificationSettingsScope scope_;
 
@@ -4259,7 +4259,7 @@ class UpdateScopeNotifySettingsQuery : public Td::ResultHandler {
   }
 };
 
-class ResetNotifySettingsQuery : public Td::ResultHandler {
+class ResetNotifySettingsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -4292,7 +4292,7 @@ class ResetNotifySettingsQuery : public Td::ResultHandler {
   }
 };
 
-class GetPeerSettingsQuery : public Td::ResultHandler {
+class GetPeerSettingsQuery final : public Td::ResultHandler {
   DialogId dialog_id_;
 
  public:
@@ -4320,7 +4320,7 @@ class GetPeerSettingsQuery : public Td::ResultHandler {
   }
 };
 
-class UpdatePeerSettingsQuery : public Td::ResultHandler {
+class UpdatePeerSettingsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -4370,7 +4370,7 @@ class UpdatePeerSettingsQuery : public Td::ResultHandler {
   }
 };
 
-class ReportEncryptedSpamQuery : public Td::ResultHandler {
+class ReportEncryptedSpamQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -4414,7 +4414,7 @@ class ReportEncryptedSpamQuery : public Td::ResultHandler {
   }
 };
 
-class ReportPeerQuery : public Td::ResultHandler {
+class ReportPeerQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -4463,7 +4463,7 @@ class ReportPeerQuery : public Td::ResultHandler {
   }
 };
 
-class ReportProfilePhotoQuery : public Td::ResultHandler {
+class ReportProfilePhotoQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
   FileId file_id_;
@@ -4527,7 +4527,7 @@ class ReportProfilePhotoQuery : public Td::ResultHandler {
   }
 };
 
-class EditPeerFoldersQuery : public Td::ResultHandler {
+class EditPeerFoldersQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -4570,7 +4570,7 @@ class EditPeerFoldersQuery : public Td::ResultHandler {
   }
 };
 
-class GetStatsUrlQuery : public Td::ResultHandler {
+class GetStatsUrlQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::httpUrl>> promise_;
   DialogId dialog_id_;
 
@@ -4606,7 +4606,7 @@ class GetStatsUrlQuery : public Td::ResultHandler {
   }
 };
 
-class GetChannelDifferenceQuery : public Td::ResultHandler {
+class GetChannelDifferenceQuery final : public Td::ResultHandler {
   DialogId dialog_id_;
   int32 pts_;
   int32 limit_;
@@ -4647,7 +4647,7 @@ class GetChannelDifferenceQuery : public Td::ResultHandler {
   }
 };
 
-class ResolveUsernameQuery : public Td::ResultHandler {
+class ResolveUsernameQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   string username_;
 
@@ -4686,7 +4686,7 @@ class ResolveUsernameQuery : public Td::ResultHandler {
   }
 };
 
-class GetChannelAdminLogQuery : public Td::ResultHandler {
+class GetChannelAdminLogQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   ChannelId channel_id_;
   int64 random_id_;
@@ -4733,7 +4733,7 @@ class GetChannelAdminLogQuery : public Td::ResultHandler {
   }
 };
 
-class MessagesManager::UploadMediaCallback : public FileManager::UploadCallback {
+class MessagesManager::UploadMediaCallback final : public FileManager::UploadCallback {
  public:
   void on_progress(FileId file_id) final {
   }
@@ -4753,7 +4753,7 @@ class MessagesManager::UploadMediaCallback : public FileManager::UploadCallback
   }
 };
 
-class MessagesManager::UploadThumbnailCallback : public FileManager::UploadCallback {
+class MessagesManager::UploadThumbnailCallback final : public FileManager::UploadCallback {
  public:
   void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) final {
     send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_thumbnail, file_id, std::move(input_file));
@@ -4769,7 +4769,7 @@ class MessagesManager::UploadThumbnailCallback : public FileManager::UploadCallb
   }
 };
 
-class MessagesManager::UploadDialogPhotoCallback : public FileManager::UploadCallback {
+class MessagesManager::UploadDialogPhotoCallback final : public FileManager::UploadCallback {
  public:
   void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) final {
     send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_dialog_photo, file_id,
@@ -4787,7 +4787,7 @@ class MessagesManager::UploadDialogPhotoCallback : public FileManager::UploadCal
   }
 };
 
-class MessagesManager::UploadImportedMessagesCallback : public FileManager::UploadCallback {
+class MessagesManager::UploadImportedMessagesCallback final : public FileManager::UploadCallback {
  public:
   void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) final {
     send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_imported_messages, file_id,
@@ -4805,7 +4805,7 @@ class MessagesManager::UploadImportedMessagesCallback : public FileManager::Uplo
   }
 };
 
-class MessagesManager::UploadImportedMessageAttachmentCallback : public FileManager::UploadCallback {
+class MessagesManager::UploadImportedMessageAttachmentCallback final : public FileManager::UploadCallback {
  public:
   void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) final {
     send_closure_later(G()->messages_manager(), &MessagesManager::on_upload_imported_message_attachment, file_id,
@@ -8500,7 +8500,7 @@ Result<string> MessagesManager::get_login_button_url(FullMessageId full_message_
 }
 
 void MessagesManager::load_secret_thumbnail(FileId thumbnail_file_id) {
-  class Callback : public FileManager::DownloadCallback {
+  class Callback final : public FileManager::DownloadCallback {
    public:
     explicit Callback(Promise<> download_promise) : download_promise_(std::move(download_promise)) {
     }
diff --git a/td/telegram/MessagesManager.h b/td/telegram/MessagesManager.h
index 540dd1161..9641fc8a1 100644
--- a/td/telegram/MessagesManager.h
+++ b/td/telegram/MessagesManager.h
@@ -89,7 +89,7 @@ class MessageContent;
 class MultiSequenceDispatcher;
 class Td;
 
-class MessagesManager : public Actor {
+class MessagesManager final : public Actor {
  public:
   //  static constexpr int32 MESSAGE_FLAG_IS_UNREAD = 1 << 0;
   static constexpr int32 MESSAGE_FLAG_IS_OUT = 1 << 1;
@@ -1539,7 +1539,7 @@ class MessagesManager : public Actor {
     }
   };
 
-  class MessagesIterator : public MessagesIteratorBase {
+  class MessagesIterator final : public MessagesIteratorBase {
    public:
     MessagesIterator() = default;
 
@@ -1553,7 +1553,7 @@ class MessagesManager : public Actor {
     }
   };
 
-  class MessagesConstIterator : public MessagesIteratorBase {
+  class MessagesConstIterator final : public MessagesIteratorBase {
    public:
     MessagesConstIterator() = default;
 
@@ -2988,7 +2988,7 @@ class MessagesManager : public Actor {
       being_loaded_secret_thumbnails_;  // thumbnail_file_id -> ...
 
   // TTL
-  class TtlNode : private HeapNode {
+  class TtlNode final : private HeapNode {
    public:
     TtlNode(DialogId dialog_id, MessageId message_id, bool by_ttl_period)
         : full_message_id_(dialog_id, message_id), by_ttl_period_(by_ttl_period) {
diff --git a/td/telegram/NotificationManager.cpp b/td/telegram/NotificationManager.cpp
index 8362341af..1beb52f97 100644
--- a/td/telegram/NotificationManager.cpp
+++ b/td/telegram/NotificationManager.cpp
@@ -67,7 +67,7 @@ namespace td {
 
 int VERBOSITY_NAME(notifications) = VERBOSITY_NAME(INFO);
 
-class SetContactSignUpNotificationQuery : public Td::ResultHandler {
+class SetContactSignUpNotificationQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -95,7 +95,7 @@ class SetContactSignUpNotificationQuery : public Td::ResultHandler {
   }
 };
 
-class GetContactSignUpNotificationQuery : public Td::ResultHandler {
+class GetContactSignUpNotificationQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -288,7 +288,7 @@ void NotificationManager::init() {
     }
   }
 
-  class StateCallback : public StateManager::Callback {
+  class StateCallback final : public StateManager::Callback {
    public:
     explicit StateCallback(ActorId<NotificationManager> parent) : parent_(std::move(parent)) {
     }
diff --git a/td/telegram/NotificationManager.h b/td/telegram/NotificationManager.h
index 8f1ee4810..0f5f251e5 100644
--- a/td/telegram/NotificationManager.h
+++ b/td/telegram/NotificationManager.h
@@ -42,7 +42,7 @@ struct BinlogEvent;
 
 class Td;
 
-class NotificationManager : public Actor {
+class NotificationManager final : public Actor {
  public:
   static constexpr int32 MIN_NOTIFICATION_GROUP_COUNT_MAX = 0;
   static constexpr int32 MAX_NOTIFICATION_GROUP_COUNT_MAX = 25;
diff --git a/td/telegram/NotificationType.cpp b/td/telegram/NotificationType.cpp
index 479fc42c4..033587cde 100644
--- a/td/telegram/NotificationType.cpp
+++ b/td/telegram/NotificationType.cpp
@@ -24,7 +24,7 @@
 
 namespace td {
 
-class NotificationTypeMessage : public NotificationType {
+class NotificationTypeMessage final : public NotificationType {
   bool can_be_delayed() const final {
     return message_id_.is_valid() && message_id_.is_server();
   }
@@ -60,7 +60,7 @@ class NotificationTypeMessage : public NotificationType {
   }
 };
 
-class NotificationTypeSecretChat : public NotificationType {
+class NotificationTypeSecretChat final : public NotificationType {
   bool can_be_delayed() const final {
     return false;
   }
@@ -90,7 +90,7 @@ class NotificationTypeSecretChat : public NotificationType {
   }
 };
 
-class NotificationTypeCall : public NotificationType {
+class NotificationTypeCall final : public NotificationType {
   bool can_be_delayed() const final {
     return false;
   }
@@ -122,7 +122,7 @@ class NotificationTypeCall : public NotificationType {
   }
 };
 
-class NotificationTypePushMessage : public NotificationType {
+class NotificationTypePushMessage final : public NotificationType {
   bool can_be_delayed() const final {
     return false;
   }
diff --git a/td/telegram/PasswordManager.h b/td/telegram/PasswordManager.h
index 13d6b09d1..d622352db 100644
--- a/td/telegram/PasswordManager.h
+++ b/td/telegram/PasswordManager.h
@@ -49,7 +49,7 @@ struct TempPasswordState {
   }
 };
 
-class PasswordManager : public NetQueryCallback {
+class PasswordManager final : public NetQueryCallback {
  public:
   using State = tl_object_ptr<td_api::passwordState>;
   using TempState = tl_object_ptr<td_api::temporaryPasswordState>;
diff --git a/td/telegram/Payments.cpp b/td/telegram/Payments.cpp
index e9072ce37..932118418 100644
--- a/td/telegram/Payments.cpp
+++ b/td/telegram/Payments.cpp
@@ -31,7 +31,7 @@
 
 namespace td {
 
-class SetBotShippingAnswerQuery : public Td::ResultHandler {
+class SetBotShippingAnswerQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -69,7 +69,7 @@ class SetBotShippingAnswerQuery : public Td::ResultHandler {
   }
 };
 
-class SetBotPreCheckoutAnswerQuery : public Td::ResultHandler {
+class SetBotPreCheckoutAnswerQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -259,7 +259,7 @@ static tl_object_ptr<td_api::savedCredentials> convert_saved_credentials(
                                                   std::move(saved_credentials->title_));
 }
 
-class GetPaymentFormQuery : public Td::ResultHandler {
+class GetPaymentFormQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::paymentForm>> promise_;
   DialogId dialog_id_;
 
@@ -322,7 +322,7 @@ class GetPaymentFormQuery : public Td::ResultHandler {
   }
 };
 
-class ValidateRequestedInfoQuery : public Td::ResultHandler {
+class ValidateRequestedInfoQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::validatedOrderInfo>> promise_;
   DialogId dialog_id_;
 
@@ -371,7 +371,7 @@ class ValidateRequestedInfoQuery : public Td::ResultHandler {
   }
 };
 
-class SendPaymentFormQuery : public Td::ResultHandler {
+class SendPaymentFormQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::paymentResult>> promise_;
   DialogId dialog_id_;
 
@@ -440,7 +440,7 @@ class SendPaymentFormQuery : public Td::ResultHandler {
   }
 };
 
-class GetPaymentReceiptQuery : public Td::ResultHandler {
+class GetPaymentReceiptQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::paymentReceipt>> promise_;
   DialogId dialog_id_;
 
@@ -498,7 +498,7 @@ class GetPaymentReceiptQuery : public Td::ResultHandler {
   }
 };
 
-class GetSavedInfoQuery : public Td::ResultHandler {
+class GetSavedInfoQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::orderInfo>> promise_;
 
  public:
@@ -525,7 +525,7 @@ class GetSavedInfoQuery : public Td::ResultHandler {
   }
 };
 
-class ClearSavedInfoQuery : public Td::ResultHandler {
+class ClearSavedInfoQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -559,7 +559,7 @@ class ClearSavedInfoQuery : public Td::ResultHandler {
   }
 };
 
-class GetBankCardInfoQuery : public Td::ResultHandler {
+class GetBankCardInfoQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::bankCardInfo>> promise_;
 
  public:
diff --git a/td/telegram/PhoneNumberManager.h b/td/telegram/PhoneNumberManager.h
index c622d3127..da71ce238 100644
--- a/td/telegram/PhoneNumberManager.h
+++ b/td/telegram/PhoneNumberManager.h
@@ -18,7 +18,7 @@
 
 namespace td {
 
-class PhoneNumberManager : public NetActor {
+class PhoneNumberManager final : public NetActor {
  public:
   enum class Type : int32 { ChangePhone, VerifyPhone, ConfirmPhone };
   PhoneNumberManager(Type type, ActorShared<> parent);
diff --git a/td/telegram/Photo.h b/td/telegram/Photo.h
index 1d594262c..47a87847c 100644
--- a/td/telegram/Photo.h
+++ b/td/telegram/Photo.h
@@ -40,7 +40,7 @@ struct DialogPhoto {
   bool has_animation = false;
 };
 
-struct ProfilePhoto : public DialogPhoto {
+struct ProfilePhoto final : public DialogPhoto {
   int64 id = 0;
 };
 
@@ -52,7 +52,7 @@ struct PhotoSize {
   vector<int32> progressive_sizes;
 };
 
-struct AnimationSize : public PhotoSize {
+struct AnimationSize final : public PhotoSize {
   double main_frame_timestamp = 0.0;
 };
 
diff --git a/td/telegram/PhotoSizeSource.h b/td/telegram/PhotoSizeSource.h
index baf801b72..c67f5c69e 100644
--- a/td/telegram/PhotoSizeSource.h
+++ b/td/telegram/PhotoSizeSource.h
@@ -65,11 +65,11 @@ struct PhotoSizeSource {
     int64 dialog_access_hash = 0;
   };
 
-  struct DialogPhotoSmall : public DialogPhoto {
+  struct DialogPhotoSmall final : public DialogPhoto {
     using DialogPhoto::DialogPhoto;
   };
 
-  struct DialogPhotoBig : public DialogPhoto {
+  struct DialogPhotoBig final : public DialogPhoto {
     using DialogPhoto::DialogPhoto;
   };
 
@@ -111,16 +111,16 @@ struct PhotoSizeSource {
     int32 local_id = 0;
   };
 
-  struct DialogPhotoSmallLegacy : public DialogPhotoLegacy {
+  struct DialogPhotoSmallLegacy final : public DialogPhotoLegacy {
     using DialogPhotoLegacy::DialogPhotoLegacy;
   };
 
-  struct DialogPhotoBigLegacy : public DialogPhotoLegacy {
+  struct DialogPhotoBigLegacy final : public DialogPhotoLegacy {
     using DialogPhotoLegacy::DialogPhotoLegacy;
   };
 
   // for legacy sticker set thumbnails
-  struct StickerSetThumbnailLegacy : public StickerSetThumbnail {
+  struct StickerSetThumbnailLegacy final : public StickerSetThumbnail {
     StickerSetThumbnailLegacy() = default;
     StickerSetThumbnailLegacy(int64 sticker_set_id, int64 sticker_set_access_hash, int64 volume_id, int32 local_id)
         : StickerSetThumbnail(sticker_set_id, sticker_set_access_hash), volume_id(volume_id), local_id(local_id) {
@@ -131,7 +131,7 @@ struct PhotoSizeSource {
   };
 
   // for sticker set thumbnails identified by version
-  struct StickerSetThumbnailVersion : public StickerSetThumbnail {
+  struct StickerSetThumbnailVersion final : public StickerSetThumbnail {
     StickerSetThumbnailVersion() = default;
     StickerSetThumbnailVersion(int64 sticker_set_id, int64 sticker_set_access_hash, int32 version)
         : StickerSetThumbnail(sticker_set_id, sticker_set_access_hash), version(version) {
diff --git a/td/telegram/PollManager.cpp b/td/telegram/PollManager.cpp
index ab634428b..28b88c1d3 100644
--- a/td/telegram/PollManager.cpp
+++ b/td/telegram/PollManager.cpp
@@ -48,7 +48,7 @@
 
 namespace td {
 
-class GetPollResultsQuery : public Td::ResultHandler {
+class GetPollResultsQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::Updates>> promise_;
   PollId poll_id_;
   DialogId dialog_id_;
@@ -89,7 +89,7 @@ class GetPollResultsQuery : public Td::ResultHandler {
   }
 };
 
-class GetPollVotersQuery : public Td::ResultHandler {
+class GetPollVotersQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::messages_votesList>> promise_;
   PollId poll_id_;
   DialogId dialog_id_;
@@ -137,7 +137,7 @@ class GetPollVotersQuery : public Td::ResultHandler {
   }
 };
 
-class SetPollAnswerActor : public NetActorOnce {
+class SetPollAnswerActor final : public NetActorOnce {
   Promise<tl_object_ptr<telegram_api::Updates>> promise_;
   DialogId dialog_id_;
 
@@ -179,7 +179,7 @@ class SetPollAnswerActor : public NetActorOnce {
   }
 };
 
-class StopPollActor : public NetActorOnce {
+class StopPollActor final : public NetActorOnce {
   Promise<Unit> promise_;
   DialogId dialog_id_;
 
@@ -247,7 +247,7 @@ PollManager::PollManager(Td *td, ActorShared<> parent) : td_(td), parent_(std::m
 }
 
 void PollManager::start_up() {
-  class StateCallback : public StateManager::Callback {
+  class StateCallback final : public StateManager::Callback {
    public:
     explicit StateCallback(ActorId<PollManager> parent) : parent_(std::move(parent)) {
     }
diff --git a/td/telegram/PollManager.h b/td/telegram/PollManager.h
index 367616b2e..c26ab5a59 100644
--- a/td/telegram/PollManager.h
+++ b/td/telegram/PollManager.h
@@ -33,7 +33,7 @@ struct BinlogEvent;
 
 class Td;
 
-class PollManager : public Actor {
+class PollManager final : public Actor {
  public:
   PollManager(Td *td, ActorShared<> parent);
 
diff --git a/td/telegram/PrivacyManager.h b/td/telegram/PrivacyManager.h
index febf09e7b..7567bb9dc 100644
--- a/td/telegram/PrivacyManager.h
+++ b/td/telegram/PrivacyManager.h
@@ -22,7 +22,7 @@
 
 namespace td {
 
-class PrivacyManager : public NetQueryCallback {
+class PrivacyManager final : public NetQueryCallback {
  public:
   explicit PrivacyManager(ActorShared<> parent) : parent_(std::move(parent)) {
   }
diff --git a/td/telegram/QueryCombiner.h b/td/telegram/QueryCombiner.h
index 5ff29b2f1..140a0b79c 100644
--- a/td/telegram/QueryCombiner.h
+++ b/td/telegram/QueryCombiner.h
@@ -19,7 +19,7 @@
 namespace td {
 
 // combines identical queries into one request
-class QueryCombiner : public Actor {
+class QueryCombiner final : public Actor {
  public:
   QueryCombiner(Slice name, double min_delay);
 
diff --git a/td/telegram/SecretChatActor.h b/td/telegram/SecretChatActor.h
index 838fd43ec..4726bb540 100644
--- a/td/telegram/SecretChatActor.h
+++ b/td/telegram/SecretChatActor.h
@@ -46,7 +46,7 @@ namespace td {
 class BinlogInterface;
 class NetQueryCreator;
 
-class SecretChatActor : public NetQueryCallback {
+class SecretChatActor final : public NetQueryCallback {
  public:
   enum : int32 {
     DEFAULT_LAYER = 73,
diff --git a/td/telegram/SecretChatsManager.cpp b/td/telegram/SecretChatsManager.cpp
index f37a89b87..2ca5cfd15 100644
--- a/td/telegram/SecretChatsManager.cpp
+++ b/td/telegram/SecretChatsManager.cpp
@@ -82,7 +82,7 @@ void SecretChatsManager::start_up() {
     return;
   }
 
-  class StateCallback : public StateManager::Callback {
+  class StateCallback final : public StateManager::Callback {
    public:
     explicit StateCallback(ActorId<SecretChatsManager> parent) : parent_(std::move(parent)) {
     }
@@ -291,7 +291,7 @@ ActorId<SecretChatActor> SecretChatsManager::create_chat_actor(int32 id) {
 }
 
 unique_ptr<SecretChatActor::Context> SecretChatsManager::make_secret_chat_context(int32 id) {
-  class Context : public SecretChatActor::Context {
+  class Context final : public SecretChatActor::Context {
    public:
     Context(int32 id, ActorShared<SecretChatsManager> parent, unique_ptr<SecretChatDb> secret_chat_db)
         : secret_chat_id_(SecretChatId(id)), parent_(std::move(parent)), secret_chat_db_(std::move(secret_chat_db)) {
diff --git a/td/telegram/SecretChatsManager.h b/td/telegram/SecretChatsManager.h
index 0265af504..c11eba855 100644
--- a/td/telegram/SecretChatsManager.h
+++ b/td/telegram/SecretChatsManager.h
@@ -27,7 +27,7 @@ namespace td {
 
 struct BinlogEvent;
 
-class SecretChatsManager : public Actor {
+class SecretChatsManager final : public Actor {
  public:
   explicit SecretChatsManager(ActorShared<> parent);
 
diff --git a/td/telegram/SecureManager.cpp b/td/telegram/SecureManager.cpp
index 96a0a13cd..41db3ed1b 100644
--- a/td/telegram/SecureManager.cpp
+++ b/td/telegram/SecureManager.cpp
@@ -29,7 +29,7 @@
 
 namespace td {
 
-class GetSecureValue : public NetQueryCallback {
+class GetSecureValue final : public NetQueryCallback {
  public:
   GetSecureValue(ActorShared<SecureManager> parent, std::string password, SecureValueType type,
                  Promise<SecureValueWithCredentials> promise);
@@ -50,7 +50,7 @@ class GetSecureValue : public NetQueryCallback {
   void on_result(NetQueryPtr query) final;
 };
 
-class GetAllSecureValues : public NetQueryCallback {
+class GetAllSecureValues final : public NetQueryCallback {
  public:
   GetAllSecureValues(ActorShared<SecureManager> parent, std::string password, Promise<TdApiSecureValues> promise);
 
@@ -69,7 +69,7 @@ class GetAllSecureValues : public NetQueryCallback {
   void on_result(NetQueryPtr query) final;
 };
 
-class SetSecureValue : public NetQueryCallback {
+class SetSecureValue final : public NetQueryCallback {
  public:
   SetSecureValue(ActorShared<SecureManager> parent, string password, SecureValue secure_value,
                  Promise<SecureValueWithCredentials> promise);
@@ -94,7 +94,7 @@ class SetSecureValue : public NetQueryCallback {
 
   enum class State : int32 { WaitSecret, WaitSetValue } state_ = State::WaitSecret;
 
-  class UploadCallback : public FileManager::UploadCallback {
+  class UploadCallback final : public FileManager::UploadCallback {
    public:
     UploadCallback(ActorId<SetSecureValue> actor_id, uint32 upload_generation);
 
@@ -128,7 +128,7 @@ class SetSecureValue : public NetQueryCallback {
   void merge(FileManager *file_manager, FileId file_id, EncryptedSecureFile &encrypted_file);
 };
 
-class SetSecureValueErrorsQuery : public Td::ResultHandler {
+class SetSecureValueErrorsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -652,7 +652,7 @@ void SetSecureValue::merge(FileManager *file_manager, FileId file_id, EncryptedS
   LOG_IF(ERROR, status.is_error()) << status.error();
 }
 
-class DeleteSecureValue : public NetQueryCallback {
+class DeleteSecureValue final : public NetQueryCallback {
  public:
   DeleteSecureValue(ActorShared<SecureManager> parent, SecureValueType type, Promise<Unit> promise)
       : parent_(std::move(parent)), type_(std::move(type)), promise_(std::move(promise)) {
@@ -681,7 +681,7 @@ class DeleteSecureValue : public NetQueryCallback {
   }
 };
 
-class GetPassportAuthorizationForm : public NetQueryCallback {
+class GetPassportAuthorizationForm final : public NetQueryCallback {
  public:
   GetPassportAuthorizationForm(ActorShared<SecureManager> parent, UserId bot_user_id, string scope, string public_key,
                                Promise<telegram_api::object_ptr<telegram_api::account_authorizationForm>> promise)
@@ -752,7 +752,7 @@ void SecureManager::get_secure_value(std::string password, SecureValueType type,
       .release();
 }
 
-class GetPassportConfig : public NetQueryCallback {
+class GetPassportConfig final : public NetQueryCallback {
  public:
   GetPassportConfig(ActorShared<SecureManager> parent, string country_code,
                     Promise<td_api::object_ptr<td_api::text>> promise)
diff --git a/td/telegram/SecureManager.h b/td/telegram/SecureManager.h
index fade3bea3..3ac79bb3c 100644
--- a/td/telegram/SecureManager.h
+++ b/td/telegram/SecureManager.h
@@ -34,7 +34,7 @@ using TdApiSecureValues = td_api::object_ptr<td_api::passportElements>;
 using TdApiSecureValuesWithErrors = td_api::object_ptr<td_api::passportElementsWithErrors>;
 using TdApiAuthorizationForm = td_api::object_ptr<td_api::passportAuthorizationForm>;
 
-class SecureManager : public NetQueryCallback {
+class SecureManager final : public NetQueryCallback {
  public:
   explicit SecureManager(ActorShared<> parent);
 
diff --git a/td/telegram/SecureStorage.cpp b/td/telegram/SecureStorage.cpp
index dd57dab7c..74d25dedb 100644
--- a/td/telegram/SecureStorage.cpp
+++ b/td/telegram/SecureStorage.cpp
@@ -90,7 +90,7 @@ BufferSlice gen_random_prefix(int64 data_size) {
   return buff;
 }
 
-class FileDataView : public DataView {
+class FileDataView final : public DataView {
  public:
   FileDataView(FileFd &fd, int64 size);
 
diff --git a/td/telegram/SecureStorage.h b/td/telegram/SecureStorage.h
index 8ffd365b7..0a4d45979 100644
--- a/td/telegram/SecureStorage.h
+++ b/td/telegram/SecureStorage.h
@@ -74,7 +74,7 @@ class DataView {
   virtual ~DataView() = default;
 };
 
-class BufferSliceDataView : public DataView {
+class BufferSliceDataView final : public DataView {
  public:
   explicit BufferSliceDataView(BufferSlice buffer_slice);
   int64 size() const final;
@@ -84,7 +84,7 @@ class BufferSliceDataView : public DataView {
   BufferSlice buffer_slice_;
 };
 
-class ConcatDataView : public DataView {
+class ConcatDataView final : public DataView {
  public:
   ConcatDataView(const DataView &left, const DataView &right);
   int64 size() const final;
@@ -161,7 +161,7 @@ class Decryptor {
 };
 
 // Encryption
-class Encryptor : public DataView {
+class Encryptor final : public DataView {
  public:
   Encryptor(AesCbcState aes_cbc_state, const DataView &data_view);
   int64 size() const final;
diff --git a/td/telegram/SequenceDispatcher.h b/td/telegram/SequenceDispatcher.h
index 5a39df42c..1a4d1858c 100644
--- a/td/telegram/SequenceDispatcher.h
+++ b/td/telegram/SequenceDispatcher.h
@@ -18,7 +18,7 @@
 
 namespace td {
 
-class SequenceDispatcher : public NetQueryCallback {
+class SequenceDispatcher final : public NetQueryCallback {
  public:
   class Parent : public Actor {
    public:
@@ -73,7 +73,7 @@ class SequenceDispatcher : public NetQueryCallback {
   void tear_down() final;
 };
 
-class MultiSequenceDispatcher : public SequenceDispatcher::Parent {
+class MultiSequenceDispatcher final : public SequenceDispatcher::Parent {
  public:
   void send_with_callback(NetQueryPtr query, ActorShared<NetQueryCallback> callback, uint64 sequence_id);
 
diff --git a/td/telegram/StickersManager.cpp b/td/telegram/StickersManager.cpp
index 74501be42..b8a47477d 100644
--- a/td/telegram/StickersManager.cpp
+++ b/td/telegram/StickersManager.cpp
@@ -61,7 +61,7 @@
 
 namespace td {
 
-class GetAllStickersQuery : public Td::ResultHandler {
+class GetAllStickersQuery final : public Td::ResultHandler {
   bool is_masks_;
 
  public:
@@ -96,7 +96,7 @@ class GetAllStickersQuery : public Td::ResultHandler {
   }
 };
 
-class SearchStickersQuery : public Td::ResultHandler {
+class SearchStickersQuery final : public Td::ResultHandler {
   string emoji_;
 
  public:
@@ -124,7 +124,7 @@ class SearchStickersQuery : public Td::ResultHandler {
   }
 };
 
-class GetEmojiKeywordsLanguageQuery : public Td::ResultHandler {
+class GetEmojiKeywordsLanguageQuery final : public Td::ResultHandler {
   Promise<vector<string>> promise_;
 
  public:
@@ -151,7 +151,7 @@ class GetEmojiKeywordsLanguageQuery : public Td::ResultHandler {
   }
 };
 
-class GetEmojiKeywordsQuery : public Td::ResultHandler {
+class GetEmojiKeywordsQuery final : public Td::ResultHandler {
   Promise<telegram_api::object_ptr<telegram_api::emojiKeywordsDifference>> promise_;
 
  public:
@@ -177,7 +177,7 @@ class GetEmojiKeywordsQuery : public Td::ResultHandler {
   }
 };
 
-class GetEmojiKeywordsDifferenceQuery : public Td::ResultHandler {
+class GetEmojiKeywordsDifferenceQuery final : public Td::ResultHandler {
   Promise<telegram_api::object_ptr<telegram_api::emojiKeywordsDifference>> promise_;
 
  public:
@@ -205,7 +205,7 @@ class GetEmojiKeywordsDifferenceQuery : public Td::ResultHandler {
   }
 };
 
-class GetEmojiUrlQuery : public Td::ResultHandler {
+class GetEmojiUrlQuery final : public Td::ResultHandler {
   Promise<telegram_api::object_ptr<telegram_api::emojiURL>> promise_;
 
  public:
@@ -231,7 +231,7 @@ class GetEmojiUrlQuery : public Td::ResultHandler {
   }
 };
 
-class GetArchivedStickerSetsQuery : public Td::ResultHandler {
+class GetArchivedStickerSetsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   StickerSetId offset_sticker_set_id_;
   bool is_masks_;
@@ -275,7 +275,7 @@ class GetArchivedStickerSetsQuery : public Td::ResultHandler {
   }
 };
 
-class GetFeaturedStickerSetsQuery : public Td::ResultHandler {
+class GetFeaturedStickerSetsQuery final : public Td::ResultHandler {
  public:
   void send(int32 hash) {
     LOG(INFO) << "Get trending sticker sets with hash " << hash;
@@ -298,7 +298,7 @@ class GetFeaturedStickerSetsQuery : public Td::ResultHandler {
   }
 };
 
-class GetOldFeaturedStickerSetsQuery : public Td::ResultHandler {
+class GetOldFeaturedStickerSetsQuery final : public Td::ResultHandler {
   int32 offset_;
   int32 limit_;
   uint32 generation_;
@@ -328,7 +328,7 @@ class GetOldFeaturedStickerSetsQuery : public Td::ResultHandler {
   }
 };
 
-class GetAttachedStickerSetsQuery : public Td::ResultHandler {
+class GetAttachedStickerSetsQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   FileId file_id_;
   string file_reference_;
@@ -377,7 +377,7 @@ class GetAttachedStickerSetsQuery : public Td::ResultHandler {
   }
 };
 
-class GetRecentStickersQuery : public Td::ResultHandler {
+class GetRecentStickersQuery final : public Td::ResultHandler {
   bool is_repair_ = false;
   bool is_attached_ = false;
 
@@ -414,7 +414,7 @@ class GetRecentStickersQuery : public Td::ResultHandler {
   }
 };
 
-class SaveRecentStickerQuery : public Td::ResultHandler {
+class SaveRecentStickerQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   FileId file_id_;
   string file_reference_;
@@ -483,7 +483,7 @@ class SaveRecentStickerQuery : public Td::ResultHandler {
   }
 };
 
-class ClearRecentStickersQuery : public Td::ResultHandler {
+class ClearRecentStickersQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   bool is_attached_;
 
@@ -527,7 +527,7 @@ class ClearRecentStickersQuery : public Td::ResultHandler {
   }
 };
 
-class GetFavedStickersQuery : public Td::ResultHandler {
+class GetFavedStickersQuery final : public Td::ResultHandler {
   bool is_repair_ = false;
 
  public:
@@ -555,7 +555,7 @@ class GetFavedStickersQuery : public Td::ResultHandler {
   }
 };
 
-class FaveStickerQuery : public Td::ResultHandler {
+class FaveStickerQuery final : public Td::ResultHandler {
   FileId file_id_;
   string file_reference_;
   bool unsave_ = false;
@@ -616,7 +616,7 @@ class FaveStickerQuery : public Td::ResultHandler {
   }
 };
 
-class ReorderStickerSetsQuery : public Td::ResultHandler {
+class ReorderStickerSetsQuery final : public Td::ResultHandler {
   bool is_masks_;
 
  public:
@@ -650,7 +650,7 @@ class ReorderStickerSetsQuery : public Td::ResultHandler {
   }
 };
 
-class GetStickerSetQuery : public Td::ResultHandler {
+class GetStickerSetQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   StickerSetId sticker_set_id_;
   string sticker_set_name_;
@@ -699,7 +699,7 @@ class GetStickerSetQuery : public Td::ResultHandler {
   }
 };
 
-class ReloadSpecialStickerSetQuery : public Td::ResultHandler {
+class ReloadSpecialStickerSetQuery final : public Td::ResultHandler {
   SpecialStickerSetType type_;
 
  public:
@@ -729,7 +729,7 @@ class ReloadSpecialStickerSetQuery : public Td::ResultHandler {
   }
 };
 
-class SearchStickerSetsQuery : public Td::ResultHandler {
+class SearchStickerSetsQuery final : public Td::ResultHandler {
   string query_;
 
  public:
@@ -758,7 +758,7 @@ class SearchStickerSetsQuery : public Td::ResultHandler {
   }
 };
 
-class InstallStickerSetQuery : public Td::ResultHandler {
+class InstallStickerSetQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   StickerSetId set_id_;
   bool is_archived_;
@@ -791,7 +791,7 @@ class InstallStickerSetQuery : public Td::ResultHandler {
   }
 };
 
-class UninstallStickerSetQuery : public Td::ResultHandler {
+class UninstallStickerSetQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   StickerSetId set_id_;
 
@@ -826,7 +826,7 @@ class UninstallStickerSetQuery : public Td::ResultHandler {
   }
 };
 
-class ReadFeaturedStickerSetsQuery : public Td::ResultHandler {
+class ReadFeaturedStickerSetsQuery final : public Td::ResultHandler {
  public:
   void send(vector<StickerSetId> sticker_set_ids) {
     LOG(INFO) << "Read trending sticker sets " << format::as_array(sticker_set_ids);
@@ -852,7 +852,7 @@ class ReadFeaturedStickerSetsQuery : public Td::ResultHandler {
   }
 };
 
-class UploadStickerFileQuery : public Td::ResultHandler {
+class UploadStickerFileQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   FileId file_id_;
   bool was_uploaded_ = false;
@@ -900,7 +900,7 @@ class UploadStickerFileQuery : public Td::ResultHandler {
   }
 };
 
-class SuggestStickerSetShortNameQuery : public Td::ResultHandler {
+class SuggestStickerSetShortNameQuery final : public Td::ResultHandler {
   Promise<string> promise_;
 
  public:
@@ -928,7 +928,7 @@ class SuggestStickerSetShortNameQuery : public Td::ResultHandler {
   }
 };
 
-class CheckStickerSetShortNameQuery : public Td::ResultHandler {
+class CheckStickerSetShortNameQuery final : public Td::ResultHandler {
   Promise<bool> promise_;
 
  public:
@@ -953,7 +953,7 @@ class CheckStickerSetShortNameQuery : public Td::ResultHandler {
   }
 };
 
-class CreateNewStickerSetQuery : public Td::ResultHandler {
+class CreateNewStickerSetQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -999,7 +999,7 @@ class CreateNewStickerSetQuery : public Td::ResultHandler {
   }
 };
 
-class AddStickerToSetQuery : public Td::ResultHandler {
+class AddStickerToSetQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -1029,7 +1029,7 @@ class AddStickerToSetQuery : public Td::ResultHandler {
   }
 };
 
-class SetStickerSetThumbnailQuery : public Td::ResultHandler {
+class SetStickerSetThumbnailQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -1059,7 +1059,7 @@ class SetStickerSetThumbnailQuery : public Td::ResultHandler {
   }
 };
 
-class SetStickerPositionQuery : public Td::ResultHandler {
+class SetStickerPositionQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -1089,7 +1089,7 @@ class SetStickerPositionQuery : public Td::ResultHandler {
   }
 };
 
-class DeleteStickerFromSetQuery : public Td::ResultHandler {
+class DeleteStickerFromSetQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -1167,7 +1167,7 @@ class StickersManager::StickerSetListLogEvent {
   }
 };
 
-class StickersManager::UploadStickerFileCallback : public FileManager::UploadCallback {
+class StickersManager::UploadStickerFileCallback final : public FileManager::UploadCallback {
  public:
   void on_upload_ok(FileId file_id, tl_object_ptr<telegram_api::InputFile> input_file) final {
     send_closure_later(G()->stickers_manager(), &StickersManager::on_upload_sticker_file, file_id,
diff --git a/td/telegram/StickersManager.h b/td/telegram/StickersManager.h
index 8697e7e2a..b19311c7b 100644
--- a/td/telegram/StickersManager.h
+++ b/td/telegram/StickersManager.h
@@ -38,7 +38,7 @@ namespace td {
 
 class Td;
 
-class StickersManager : public Actor {
+class StickersManager final : public Actor {
  public:
   static constexpr int64 GREAT_MINDS_SET_ID = 1842540969984001;
 
diff --git a/td/telegram/StorageManager.h b/td/telegram/StorageManager.h
index b05dedf5b..b6715df78 100644
--- a/td/telegram/StorageManager.h
+++ b/td/telegram/StorageManager.h
@@ -29,7 +29,7 @@ struct DatabaseStats {
   tl_object_ptr<td_api::databaseStatistics> get_database_statistics_object() const;
 };
 
-class StorageManager : public Actor {
+class StorageManager final : public Actor {
  public:
   StorageManager(ActorShared<> parent, int32 scheduler_id);
   void get_storage_stats(bool need_all_files, int32 dialog_limit, Promise<FileStats> promise);
diff --git a/td/telegram/Td.cpp b/td/telegram/Td.cpp
index 9a8b66e39..74109e706 100644
--- a/td/telegram/Td.cpp
+++ b/td/telegram/Td.cpp
@@ -170,7 +170,7 @@ void Td::ResultHandler::send_query(NetQueryPtr query) {
   td->send(std::move(query));
 }
 
-class GetPromoDataQuery : public Td::ResultHandler {
+class GetPromoDataQuery final : public Td::ResultHandler {
   Promise<telegram_api::object_ptr<telegram_api::help_PromoData>> promise_;
 
  public:
@@ -197,7 +197,7 @@ class GetPromoDataQuery : public Td::ResultHandler {
   }
 };
 
-class GetRecentMeUrlsQuery : public Td::ResultHandler {
+class GetRecentMeUrlsQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<td_api::tMeUrls>> promise_;
 
  public:
@@ -296,7 +296,7 @@ class GetRecentMeUrlsQuery : public Td::ResultHandler {
   }
 };
 
-class SendCustomRequestQuery : public Td::ResultHandler {
+class SendCustomRequestQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::customRequestResult>> promise_;
 
  public:
@@ -324,7 +324,7 @@ class SendCustomRequestQuery : public Td::ResultHandler {
   }
 };
 
-class AnswerCustomQueryQuery : public Td::ResultHandler {
+class AnswerCustomQueryQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -354,7 +354,7 @@ class AnswerCustomQueryQuery : public Td::ResultHandler {
   }
 };
 
-class SetBotUpdatesStatusQuery : public Td::ResultHandler {
+class SetBotUpdatesStatusQuery final : public Td::ResultHandler {
  public:
   void send(int32 pending_update_count, const string &error_message) {
     send_query(
@@ -379,7 +379,7 @@ class SetBotUpdatesStatusQuery : public Td::ResultHandler {
   }
 };
 
-class UpdateStatusQuery : public Td::ResultHandler {
+class UpdateStatusQuery final : public Td::ResultHandler {
   bool is_offline_;
 
  public:
@@ -410,7 +410,7 @@ class UpdateStatusQuery : public Td::ResultHandler {
   }
 };
 
-class GetInviteTextQuery : public Td::ResultHandler {
+class GetInviteTextQuery final : public Td::ResultHandler {
   Promise<string> promise_;
 
  public:
@@ -436,7 +436,7 @@ class GetInviteTextQuery : public Td::ResultHandler {
   }
 };
 
-class GetDeepLinkInfoQuery : public Td::ResultHandler {
+class GetDeepLinkInfoQuery final : public Td::ResultHandler {
   Promise<td_api::object_ptr<td_api::deepLinkInfo>> promise_;
 
  public:
@@ -497,7 +497,7 @@ class GetDeepLinkInfoQuery : public Td::ResultHandler {
   }
 };
 
-class SaveAppLogQuery : public Td::ResultHandler {
+class SaveAppLogQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
@@ -528,7 +528,7 @@ class SaveAppLogQuery : public Td::ResultHandler {
   }
 };
 
-class TestQuery : public Td::ResultHandler {
+class TestQuery final : public Td::ResultHandler {
  public:
   explicit TestQuery(uint64 request_id) : request_id_(request_id) {
   }
@@ -556,7 +556,7 @@ class TestQuery : public Td::ResultHandler {
   uint64 request_id_;
 };
 
-class TestProxyRequest : public RequestOnceActor {
+class TestProxyRequest final : public RequestOnceActor {
   Proxy proxy_;
   int16 dc_id_;
   double timeout_;
@@ -604,7 +604,7 @@ class TestProxyRequest : public RequestOnceActor {
     if (r_data.is_error()) {
       return promise_.set_error(r_data.move_as_error());
     }
-    class HandshakeContext : public mtproto::AuthKeyHandshakeContext {
+    class HandshakeContext final : public mtproto::AuthKeyHandshakeContext {
      public:
       DhCallback *get_dh_callback() final {
         return nullptr;
@@ -664,7 +664,7 @@ class TestProxyRequest : public RequestOnceActor {
   }
 };
 
-class GetMeRequest : public RequestActor<> {
+class GetMeRequest final : public RequestActor<> {
   UserId user_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -680,7 +680,7 @@ class GetMeRequest : public RequestActor<> {
   }
 };
 
-class GetUserRequest : public RequestActor<> {
+class GetUserRequest final : public RequestActor<> {
   UserId user_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -698,7 +698,7 @@ class GetUserRequest : public RequestActor<> {
   }
 };
 
-class GetUserFullInfoRequest : public RequestActor<> {
+class GetUserFullInfoRequest final : public RequestActor<> {
   UserId user_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -715,7 +715,7 @@ class GetUserFullInfoRequest : public RequestActor<> {
   }
 };
 
-class GetGroupRequest : public RequestActor<> {
+class GetGroupRequest final : public RequestActor<> {
   ChatId chat_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -733,7 +733,7 @@ class GetGroupRequest : public RequestActor<> {
   }
 };
 
-class GetGroupFullInfoRequest : public RequestActor<> {
+class GetGroupFullInfoRequest final : public RequestActor<> {
   ChatId chat_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -750,7 +750,7 @@ class GetGroupFullInfoRequest : public RequestActor<> {
   }
 };
 
-class GetSupergroupRequest : public RequestActor<> {
+class GetSupergroupRequest final : public RequestActor<> {
   ChannelId channel_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -768,7 +768,7 @@ class GetSupergroupRequest : public RequestActor<> {
   }
 };
 
-class GetSupergroupFullInfoRequest : public RequestActor<> {
+class GetSupergroupFullInfoRequest final : public RequestActor<> {
   ChannelId channel_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -785,7 +785,7 @@ class GetSupergroupFullInfoRequest : public RequestActor<> {
   }
 };
 
-class GetSecretChatRequest : public RequestActor<> {
+class GetSecretChatRequest final : public RequestActor<> {
   SecretChatId secret_chat_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -802,7 +802,7 @@ class GetSecretChatRequest : public RequestActor<> {
   }
 };
 
-class GetChatRequest : public RequestActor<> {
+class GetChatRequest final : public RequestActor<> {
   DialogId dialog_id_;
 
   bool dialog_found_ = false;
@@ -826,7 +826,7 @@ class GetChatRequest : public RequestActor<> {
   }
 };
 
-class GetChatFilterRequest : public RequestActor<> {
+class GetChatFilterRequest final : public RequestActor<> {
   DialogFilterId dialog_filter_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -844,7 +844,7 @@ class GetChatFilterRequest : public RequestActor<> {
   }
 };
 
-class GetChatsRequest : public RequestActor<> {
+class GetChatsRequest final : public RequestActor<> {
   DialogListId dialog_list_id_;
   DialogDate offset_;
   int32 limit_;
@@ -872,7 +872,7 @@ class GetChatsRequest : public RequestActor<> {
   }
 };
 
-class SearchPublicChatRequest : public RequestActor<> {
+class SearchPublicChatRequest final : public RequestActor<> {
   string username_;
 
   DialogId dialog_id_;
@@ -892,7 +892,7 @@ class SearchPublicChatRequest : public RequestActor<> {
   }
 };
 
-class SearchPublicChatsRequest : public RequestActor<> {
+class SearchPublicChatsRequest final : public RequestActor<> {
   string query_;
 
   vector<DialogId> dialog_ids_;
@@ -911,7 +911,7 @@ class SearchPublicChatsRequest : public RequestActor<> {
   }
 };
 
-class SearchChatsRequest : public RequestActor<> {
+class SearchChatsRequest final : public RequestActor<> {
   string query_;
   int32 limit_;
 
@@ -931,7 +931,7 @@ class SearchChatsRequest : public RequestActor<> {
   }
 };
 
-class SearchChatsOnServerRequest : public RequestActor<> {
+class SearchChatsOnServerRequest final : public RequestActor<> {
   string query_;
   int32 limit_;
 
@@ -951,7 +951,7 @@ class SearchChatsOnServerRequest : public RequestActor<> {
   }
 };
 
-class GetGroupsInCommonRequest : public RequestActor<> {
+class GetGroupsInCommonRequest final : public RequestActor<> {
   UserId user_id_;
   DialogId offset_dialog_id_;
   int32 limit_;
@@ -973,7 +973,7 @@ class GetGroupsInCommonRequest : public RequestActor<> {
   }
 };
 
-class GetCreatedPublicChatsRequest : public RequestActor<> {
+class GetCreatedPublicChatsRequest final : public RequestActor<> {
   vector<DialogId> dialog_ids_;
   PublicDialogType type_;
 
@@ -991,7 +991,7 @@ class GetCreatedPublicChatsRequest : public RequestActor<> {
   }
 };
 
-class GetSuitableDiscussionChatsRequest : public RequestActor<> {
+class GetSuitableDiscussionChatsRequest final : public RequestActor<> {
   vector<DialogId> dialog_ids_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -1007,7 +1007,7 @@ class GetSuitableDiscussionChatsRequest : public RequestActor<> {
   }
 };
 
-class GetInactiveSupergroupChatsRequest : public RequestActor<> {
+class GetInactiveSupergroupChatsRequest final : public RequestActor<> {
   vector<DialogId> dialog_ids_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -1023,7 +1023,7 @@ class GetInactiveSupergroupChatsRequest : public RequestActor<> {
   }
 };
 
-class GetMessageRequest : public RequestOnceActor {
+class GetMessageRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -1040,7 +1040,7 @@ class GetMessageRequest : public RequestOnceActor {
   }
 };
 
-class GetRepliedMessageRequest : public RequestOnceActor {
+class GetRepliedMessageRequest final : public RequestOnceActor {
   DialogId dialog_id_;
   MessageId message_id_;
 
@@ -1062,7 +1062,7 @@ class GetRepliedMessageRequest : public RequestOnceActor {
   }
 };
 
-class GetMessageThreadRequest : public RequestActor<MessagesManager::MessageThreadInfo> {
+class GetMessageThreadRequest final : public RequestActor<MessagesManager::MessageThreadInfo> {
   DialogId dialog_id_;
   MessageId message_id_;
 
@@ -1090,7 +1090,7 @@ class GetMessageThreadRequest : public RequestActor<MessagesManager::MessageThre
   }
 };
 
-class GetChatPinnedMessageRequest : public RequestOnceActor {
+class GetChatPinnedMessageRequest final : public RequestOnceActor {
   DialogId dialog_id_;
 
   MessageId pinned_message_id_;
@@ -1110,7 +1110,7 @@ class GetChatPinnedMessageRequest : public RequestOnceActor {
   }
 };
 
-class GetCallbackQueryMessageRequest : public RequestOnceActor {
+class GetCallbackQueryMessageRequest final : public RequestOnceActor {
   DialogId dialog_id_;
   MessageId message_id_;
   int64 callback_query_id_;
@@ -1133,7 +1133,7 @@ class GetCallbackQueryMessageRequest : public RequestOnceActor {
   }
 };
 
-class GetMessagesRequest : public RequestOnceActor {
+class GetMessagesRequest final : public RequestOnceActor {
   DialogId dialog_id_;
   vector<MessageId> message_ids_;
 
@@ -1153,7 +1153,7 @@ class GetMessagesRequest : public RequestOnceActor {
   }
 };
 
-class GetMessageEmbeddingCodeRequest : public RequestActor<> {
+class GetMessageEmbeddingCodeRequest final : public RequestActor<> {
   FullMessageId full_message_id_;
   bool for_group_;
 
@@ -1176,7 +1176,7 @@ class GetMessageEmbeddingCodeRequest : public RequestActor<> {
   }
 };
 
-class GetMessageLinkInfoRequest : public RequestActor<MessageLinkInfo> {
+class GetMessageLinkInfoRequest final : public RequestActor<MessageLinkInfo> {
   string url_;
 
   MessageLinkInfo message_link_info_;
@@ -1203,7 +1203,7 @@ class GetMessageLinkInfoRequest : public RequestActor<MessageLinkInfo> {
   }
 };
 
-class EditMessageTextRequest : public RequestOnceActor {
+class EditMessageTextRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
   tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
   tl_object_ptr<td_api::InputMessageContent> input_message_content_;
@@ -1228,7 +1228,7 @@ class EditMessageTextRequest : public RequestOnceActor {
   }
 };
 
-class EditMessageLiveLocationRequest : public RequestOnceActor {
+class EditMessageLiveLocationRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
   tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
   tl_object_ptr<td_api::location> location_;
@@ -1257,7 +1257,7 @@ class EditMessageLiveLocationRequest : public RequestOnceActor {
   }
 };
 
-class EditMessageMediaRequest : public RequestOnceActor {
+class EditMessageMediaRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
   tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
   tl_object_ptr<td_api::InputMessageContent> input_message_content_;
@@ -1282,7 +1282,7 @@ class EditMessageMediaRequest : public RequestOnceActor {
   }
 };
 
-class EditMessageCaptionRequest : public RequestOnceActor {
+class EditMessageCaptionRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
   tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
   tl_object_ptr<td_api::formattedText> caption_;
@@ -1307,7 +1307,7 @@ class EditMessageCaptionRequest : public RequestOnceActor {
   }
 };
 
-class EditMessageReplyMarkupRequest : public RequestOnceActor {
+class EditMessageReplyMarkupRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
   tl_object_ptr<td_api::ReplyMarkup> reply_markup_;
 
@@ -1328,7 +1328,7 @@ class EditMessageReplyMarkupRequest : public RequestOnceActor {
   }
 };
 
-class SetGameScoreRequest : public RequestOnceActor {
+class SetGameScoreRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
   bool edit_message_;
   UserId user_id_;
@@ -1356,7 +1356,7 @@ class SetGameScoreRequest : public RequestOnceActor {
   }
 };
 
-class GetGameHighScoresRequest : public RequestOnceActor {
+class GetGameHighScoresRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
   UserId user_id_;
 
@@ -1380,7 +1380,7 @@ class GetGameHighScoresRequest : public RequestOnceActor {
   }
 };
 
-class GetInlineGameHighScoresRequest : public RequestOnceActor {
+class GetInlineGameHighScoresRequest final : public RequestOnceActor {
   string inline_message_id_;
   UserId user_id_;
 
@@ -1404,7 +1404,7 @@ class GetInlineGameHighScoresRequest : public RequestOnceActor {
   }
 };
 
-class GetChatHistoryRequest : public RequestActor<> {
+class GetChatHistoryRequest final : public RequestActor<> {
   DialogId dialog_id_;
   MessageId from_message_id_;
   int32 offset_;
@@ -1437,7 +1437,7 @@ class GetChatHistoryRequest : public RequestActor<> {
   }
 };
 
-class GetMessageThreadHistoryRequest : public RequestActor<> {
+class GetMessageThreadHistoryRequest final : public RequestActor<> {
   DialogId dialog_id_;
   MessageId message_id_;
   MessageId from_message_id_;
@@ -1470,7 +1470,7 @@ class GetMessageThreadHistoryRequest : public RequestActor<> {
   }
 };
 
-class SearchChatMessagesRequest : public RequestActor<> {
+class SearchChatMessagesRequest final : public RequestActor<> {
   DialogId dialog_id_;
   string query_;
   td_api::object_ptr<td_api::MessageSender> sender_;
@@ -1520,7 +1520,7 @@ class SearchChatMessagesRequest : public RequestActor<> {
   }
 };
 
-class SearchSecretMessagesRequest : public RequestActor<> {
+class SearchSecretMessagesRequest final : public RequestActor<> {
   DialogId dialog_id_;
   string query_;
   string offset_;
@@ -1552,7 +1552,7 @@ class SearchSecretMessagesRequest : public RequestActor<> {
   }
 };
 
-class SearchMessagesRequest : public RequestActor<> {
+class SearchMessagesRequest final : public RequestActor<> {
   FolderId folder_id_;
   bool ignore_folder_id_;
   string query_;
@@ -1605,7 +1605,7 @@ class SearchMessagesRequest : public RequestActor<> {
   }
 };
 
-class SearchCallMessagesRequest : public RequestActor<> {
+class SearchCallMessagesRequest final : public RequestActor<> {
   MessageId from_message_id_;
   int32 limit_;
   bool only_missed_;
@@ -1633,7 +1633,7 @@ class SearchCallMessagesRequest : public RequestActor<> {
   }
 };
 
-class SearchChatRecentLocationMessagesRequest : public RequestActor<> {
+class SearchChatRecentLocationMessagesRequest final : public RequestActor<> {
   DialogId dialog_id_;
   int32 limit_;
   int64 random_id_;
@@ -1655,7 +1655,7 @@ class SearchChatRecentLocationMessagesRequest : public RequestActor<> {
   }
 };
 
-class GetActiveLiveLocationMessagesRequest : public RequestActor<> {
+class GetActiveLiveLocationMessagesRequest final : public RequestActor<> {
   vector<FullMessageId> full_message_ids_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -1672,7 +1672,7 @@ class GetActiveLiveLocationMessagesRequest : public RequestActor<> {
   }
 };
 
-class GetChatMessageByDateRequest : public RequestOnceActor {
+class GetChatMessageByDateRequest final : public RequestOnceActor {
   DialogId dialog_id_;
   int32 date_;
 
@@ -1692,7 +1692,7 @@ class GetChatMessageByDateRequest : public RequestOnceActor {
   }
 };
 
-class GetChatMessageCountRequest : public RequestActor<> {
+class GetChatMessageCountRequest final : public RequestActor<> {
   DialogId dialog_id_;
   MessageSearchFilter filter_;
   bool return_local_;
@@ -1720,7 +1720,7 @@ class GetChatMessageCountRequest : public RequestActor<> {
   }
 };
 
-class GetChatScheduledMessagesRequest : public RequestActor<> {
+class GetChatScheduledMessagesRequest final : public RequestActor<> {
   DialogId dialog_id_;
 
   vector<MessageId> message_ids_;
@@ -1741,7 +1741,7 @@ class GetChatScheduledMessagesRequest : public RequestActor<> {
   }
 };
 
-class GetMessagePublicForwardsRequest : public RequestActor<> {
+class GetMessagePublicForwardsRequest final : public RequestActor<> {
   FullMessageId full_message_id_;
   string offset_;
   int32 limit_;
@@ -1769,7 +1769,7 @@ class GetMessagePublicForwardsRequest : public RequestActor<> {
   }
 };
 
-class GetWebPagePreviewRequest : public RequestOnceActor {
+class GetWebPagePreviewRequest final : public RequestOnceActor {
   td_api::object_ptr<td_api::formattedText> text_;
 
   int64 request_id_ = 0;
@@ -1788,7 +1788,7 @@ class GetWebPagePreviewRequest : public RequestOnceActor {
   }
 };
 
-class GetWebPageInstantViewRequest : public RequestActor<> {
+class GetWebPageInstantViewRequest final : public RequestActor<> {
   string url_;
   bool force_full_;
 
@@ -1810,7 +1810,7 @@ class GetWebPageInstantViewRequest : public RequestActor<> {
   }
 };
 
-class CreateChatRequest : public RequestActor<> {
+class CreateChatRequest final : public RequestActor<> {
   DialogId dialog_id_;
   bool force_;
 
@@ -1828,7 +1828,7 @@ class CreateChatRequest : public RequestActor<> {
   }
 };
 
-class CreateNewGroupChatRequest : public RequestActor<> {
+class CreateNewGroupChatRequest final : public RequestActor<> {
   vector<UserId> user_ids_;
   string title_;
   int64 random_id_;
@@ -1853,7 +1853,7 @@ class CreateNewGroupChatRequest : public RequestActor<> {
   }
 };
 
-class CreateNewSecretChatRequest : public RequestActor<SecretChatId> {
+class CreateNewSecretChatRequest final : public RequestActor<SecretChatId> {
   UserId user_id_;
   SecretChatId secret_chat_id_;
 
@@ -1888,7 +1888,7 @@ class CreateNewSecretChatRequest : public RequestActor<SecretChatId> {
   }
 };
 
-class CreateNewSupergroupChatRequest : public RequestActor<> {
+class CreateNewSupergroupChatRequest final : public RequestActor<> {
   string title_;
   bool is_megagroup_;
   string description_;
@@ -1922,7 +1922,7 @@ class CreateNewSupergroupChatRequest : public RequestActor<> {
   }
 };
 
-class UpgradeGroupChatToSupergroupChatRequest : public RequestActor<> {
+class UpgradeGroupChatToSupergroupChatRequest final : public RequestActor<> {
   string title_;
   DialogId dialog_id_;
 
@@ -1943,7 +1943,7 @@ class UpgradeGroupChatToSupergroupChatRequest : public RequestActor<> {
   }
 };
 
-class GetChatMemberRequest : public RequestActor<> {
+class GetChatMemberRequest final : public RequestActor<> {
   DialogId dialog_id_;
   DialogId participant_dialog_id_;
   int64 random_id_;
@@ -1974,7 +1974,7 @@ class GetChatMemberRequest : public RequestActor<> {
   }
 };
 
-class GetChatAdministratorsRequest : public RequestActor<> {
+class GetChatAdministratorsRequest final : public RequestActor<> {
   DialogId dialog_id_;
 
   vector<DialogAdministrator> administrators_;
@@ -1998,7 +1998,7 @@ class GetChatAdministratorsRequest : public RequestActor<> {
   }
 };
 
-class CheckChatInviteLinkRequest : public RequestActor<> {
+class CheckChatInviteLinkRequest final : public RequestActor<> {
   string invite_link_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2017,7 +2017,7 @@ class CheckChatInviteLinkRequest : public RequestActor<> {
   }
 };
 
-class JoinChatByInviteLinkRequest : public RequestActor<DialogId> {
+class JoinChatByInviteLinkRequest final : public RequestActor<DialogId> {
   string invite_link_;
 
   DialogId dialog_id_;
@@ -2046,7 +2046,7 @@ class JoinChatByInviteLinkRequest : public RequestActor<DialogId> {
   }
 };
 
-class GetChatEventLogRequest : public RequestOnceActor {
+class GetChatEventLogRequest final : public RequestOnceActor {
   DialogId dialog_id_;
   string query_;
   int64 from_event_id_;
@@ -2079,7 +2079,7 @@ class GetChatEventLogRequest : public RequestOnceActor {
   }
 };
 
-class GetBlockedMessageSendersRequest : public RequestActor<> {
+class GetBlockedMessageSendersRequest final : public RequestActor<> {
   int32 offset_;
   int32 limit_;
   int64 random_id_;
@@ -2104,7 +2104,7 @@ class GetBlockedMessageSendersRequest : public RequestActor<> {
   }
 };
 
-class ImportContactsRequest : public RequestActor<> {
+class ImportContactsRequest final : public RequestActor<> {
   vector<tl_object_ptr<td_api::contact>> contacts_;
   int64 random_id_;
 
@@ -2132,7 +2132,7 @@ class ImportContactsRequest : public RequestActor<> {
   }
 };
 
-class SearchContactsRequest : public RequestActor<> {
+class SearchContactsRequest final : public RequestActor<> {
   string query_;
   int32 limit_;
 
@@ -2152,7 +2152,7 @@ class SearchContactsRequest : public RequestActor<> {
   }
 };
 
-class RemoveContactsRequest : public RequestActor<> {
+class RemoveContactsRequest final : public RequestActor<> {
   vector<UserId> user_ids_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2166,7 +2166,7 @@ class RemoveContactsRequest : public RequestActor<> {
   }
 };
 
-class GetImportedContactCountRequest : public RequestActor<> {
+class GetImportedContactCountRequest final : public RequestActor<> {
   int32 imported_contact_count_ = 0;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2182,7 +2182,7 @@ class GetImportedContactCountRequest : public RequestActor<> {
   }
 };
 
-class ChangeImportedContactsRequest : public RequestActor<> {
+class ChangeImportedContactsRequest final : public RequestActor<> {
   vector<tl_object_ptr<td_api::contact>> contacts_;
   size_t contacts_size_;
   int64 random_id_;
@@ -2216,7 +2216,7 @@ class ChangeImportedContactsRequest : public RequestActor<> {
   }
 };
 
-class GetRecentInlineBotsRequest : public RequestActor<> {
+class GetRecentInlineBotsRequest final : public RequestActor<> {
   vector<UserId> user_ids_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2232,7 +2232,7 @@ class GetRecentInlineBotsRequest : public RequestActor<> {
   }
 };
 
-class GetUserProfilePhotosRequest : public RequestActor<> {
+class GetUserProfilePhotosRequest final : public RequestActor<> {
   UserId user_id_;
   int32 offset_;
   int32 limit_;
@@ -2259,7 +2259,7 @@ class GetUserProfilePhotosRequest : public RequestActor<> {
   }
 };
 
-class GetChatNotificationSettingsExceptionsRequest : public RequestActor<> {
+class GetChatNotificationSettingsExceptionsRequest final : public RequestActor<> {
   NotificationSettingsScope scope_;
   bool filter_scope_;
   bool compare_sound_;
@@ -2286,7 +2286,7 @@ class GetChatNotificationSettingsExceptionsRequest : public RequestActor<> {
   }
 };
 
-class GetScopeNotificationSettingsRequest : public RequestActor<> {
+class GetScopeNotificationSettingsRequest final : public RequestActor<> {
   NotificationSettingsScope scope_;
 
   const ScopeNotificationSettings *notification_settings_ = nullptr;
@@ -2306,7 +2306,7 @@ class GetScopeNotificationSettingsRequest : public RequestActor<> {
   }
 };
 
-class GetStickersRequest : public RequestActor<> {
+class GetStickersRequest final : public RequestActor<> {
   string emoji_;
   int32 limit_;
 
@@ -2327,7 +2327,7 @@ class GetStickersRequest : public RequestActor<> {
   }
 };
 
-class SearchStickersRequest : public RequestActor<> {
+class SearchStickersRequest final : public RequestActor<> {
   string emoji_;
   int32 limit_;
 
@@ -2347,7 +2347,7 @@ class SearchStickersRequest : public RequestActor<> {
   }
 };
 
-class GetInstalledStickerSetsRequest : public RequestActor<> {
+class GetInstalledStickerSetsRequest final : public RequestActor<> {
   bool is_masks_;
 
   vector<StickerSetId> sticker_set_ids_;
@@ -2366,7 +2366,7 @@ class GetInstalledStickerSetsRequest : public RequestActor<> {
   }
 };
 
-class GetArchivedStickerSetsRequest : public RequestActor<> {
+class GetArchivedStickerSetsRequest final : public RequestActor<> {
   bool is_masks_;
   StickerSetId offset_sticker_set_id_;
   int32 limit_;
@@ -2393,7 +2393,7 @@ class GetArchivedStickerSetsRequest : public RequestActor<> {
   }
 };
 
-class GetTrendingStickerSetsRequest : public RequestActor<> {
+class GetTrendingStickerSetsRequest final : public RequestActor<> {
   std::pair<int32, vector<StickerSetId>> sticker_set_ids_;
   int32 offset_;
   int32 limit_;
@@ -2413,7 +2413,7 @@ class GetTrendingStickerSetsRequest : public RequestActor<> {
   }
 };
 
-class GetAttachedStickerSetsRequest : public RequestActor<> {
+class GetAttachedStickerSetsRequest final : public RequestActor<> {
   FileId file_id_;
 
   vector<StickerSetId> sticker_set_ids_;
@@ -2432,7 +2432,7 @@ class GetAttachedStickerSetsRequest : public RequestActor<> {
   }
 };
 
-class GetStickerSetRequest : public RequestActor<> {
+class GetStickerSetRequest final : public RequestActor<> {
   StickerSetId set_id_;
 
   StickerSetId sticker_set_id_;
@@ -2452,7 +2452,7 @@ class GetStickerSetRequest : public RequestActor<> {
   }
 };
 
-class SearchStickerSetRequest : public RequestActor<> {
+class SearchStickerSetRequest final : public RequestActor<> {
   string name_;
 
   StickerSetId sticker_set_id_;
@@ -2472,7 +2472,7 @@ class SearchStickerSetRequest : public RequestActor<> {
   }
 };
 
-class SearchInstalledStickerSetsRequest : public RequestActor<> {
+class SearchInstalledStickerSetsRequest final : public RequestActor<> {
   bool is_masks_;
   string query_;
   int32 limit_;
@@ -2494,7 +2494,7 @@ class SearchInstalledStickerSetsRequest : public RequestActor<> {
   }
 };
 
-class SearchStickerSetsRequest : public RequestActor<> {
+class SearchStickerSetsRequest final : public RequestActor<> {
   string query_;
 
   vector<StickerSetId> sticker_set_ids_;
@@ -2513,7 +2513,7 @@ class SearchStickerSetsRequest : public RequestActor<> {
   }
 };
 
-class ChangeStickerSetRequest : public RequestOnceActor {
+class ChangeStickerSetRequest final : public RequestOnceActor {
   StickerSetId set_id_;
   bool is_installed_;
   bool is_archived_;
@@ -2532,7 +2532,7 @@ class ChangeStickerSetRequest : public RequestOnceActor {
   }
 };
 
-class UploadStickerFileRequest : public RequestOnceActor {
+class UploadStickerFileRequest final : public RequestOnceActor {
   UserId user_id_;
   tl_object_ptr<td_api::InputSticker> sticker_;
 
@@ -2553,7 +2553,7 @@ class UploadStickerFileRequest : public RequestOnceActor {
   }
 };
 
-class CreateNewStickerSetRequest : public RequestOnceActor {
+class CreateNewStickerSetRequest final : public RequestOnceActor {
   UserId user_id_;
   string title_;
   string name_;
@@ -2587,7 +2587,7 @@ class CreateNewStickerSetRequest : public RequestOnceActor {
   }
 };
 
-class AddStickerToSetRequest : public RequestOnceActor {
+class AddStickerToSetRequest final : public RequestOnceActor {
   UserId user_id_;
   string name_;
   tl_object_ptr<td_api::InputSticker> sticker_;
@@ -2614,7 +2614,7 @@ class AddStickerToSetRequest : public RequestOnceActor {
   }
 };
 
-class SetStickerSetThumbnailRequest : public RequestOnceActor {
+class SetStickerSetThumbnailRequest final : public RequestOnceActor {
   UserId user_id_;
   string name_;
   tl_object_ptr<td_api::InputFile> thumbnail_;
@@ -2641,7 +2641,7 @@ class SetStickerSetThumbnailRequest : public RequestOnceActor {
   }
 };
 
-class GetRecentStickersRequest : public RequestActor<> {
+class GetRecentStickersRequest final : public RequestActor<> {
   bool is_attached_;
 
   vector<FileId> sticker_ids_;
@@ -2660,7 +2660,7 @@ class GetRecentStickersRequest : public RequestActor<> {
   }
 };
 
-class AddRecentStickerRequest : public RequestActor<> {
+class AddRecentStickerRequest final : public RequestActor<> {
   bool is_attached_;
   tl_object_ptr<td_api::InputFile> input_file_;
 
@@ -2676,7 +2676,7 @@ class AddRecentStickerRequest : public RequestActor<> {
   }
 };
 
-class RemoveRecentStickerRequest : public RequestActor<> {
+class RemoveRecentStickerRequest final : public RequestActor<> {
   bool is_attached_;
   tl_object_ptr<td_api::InputFile> input_file_;
 
@@ -2692,7 +2692,7 @@ class RemoveRecentStickerRequest : public RequestActor<> {
   }
 };
 
-class ClearRecentStickersRequest : public RequestActor<> {
+class ClearRecentStickersRequest final : public RequestActor<> {
   bool is_attached_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2706,7 +2706,7 @@ class ClearRecentStickersRequest : public RequestActor<> {
   }
 };
 
-class GetFavoriteStickersRequest : public RequestActor<> {
+class GetFavoriteStickersRequest final : public RequestActor<> {
   vector<FileId> sticker_ids_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2722,7 +2722,7 @@ class GetFavoriteStickersRequest : public RequestActor<> {
   }
 };
 
-class AddFavoriteStickerRequest : public RequestOnceActor {
+class AddFavoriteStickerRequest final : public RequestOnceActor {
   tl_object_ptr<td_api::InputFile> input_file_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2736,7 +2736,7 @@ class AddFavoriteStickerRequest : public RequestOnceActor {
   }
 };
 
-class RemoveFavoriteStickerRequest : public RequestOnceActor {
+class RemoveFavoriteStickerRequest final : public RequestOnceActor {
   tl_object_ptr<td_api::InputFile> input_file_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2750,7 +2750,7 @@ class RemoveFavoriteStickerRequest : public RequestOnceActor {
   }
 };
 
-class GetStickerEmojisRequest : public RequestActor<> {
+class GetStickerEmojisRequest final : public RequestActor<> {
   tl_object_ptr<td_api::InputFile> input_file_;
 
   vector<string> emojis_;
@@ -2770,7 +2770,7 @@ class GetStickerEmojisRequest : public RequestActor<> {
   }
 };
 
-class SearchEmojisRequest : public RequestActor<> {
+class SearchEmojisRequest final : public RequestActor<> {
   string text_;
   bool exact_match_;
   vector<string> input_language_codes_;
@@ -2797,7 +2797,7 @@ class SearchEmojisRequest : public RequestActor<> {
   }
 };
 
-class GetEmojiSuggestionsUrlRequest : public RequestOnceActor {
+class GetEmojiSuggestionsUrlRequest final : public RequestOnceActor {
   string language_code_;
 
   int64 random_id_;
@@ -2816,7 +2816,7 @@ class GetEmojiSuggestionsUrlRequest : public RequestOnceActor {
   }
 };
 
-class GetSavedAnimationsRequest : public RequestActor<> {
+class GetSavedAnimationsRequest final : public RequestActor<> {
   vector<FileId> animation_ids_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2834,7 +2834,7 @@ class GetSavedAnimationsRequest : public RequestActor<> {
   }
 };
 
-class AddSavedAnimationRequest : public RequestOnceActor {
+class AddSavedAnimationRequest final : public RequestOnceActor {
   tl_object_ptr<td_api::InputFile> input_file_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2848,7 +2848,7 @@ class AddSavedAnimationRequest : public RequestOnceActor {
   }
 };
 
-class RemoveSavedAnimationRequest : public RequestOnceActor {
+class RemoveSavedAnimationRequest final : public RequestOnceActor {
   tl_object_ptr<td_api::InputFile> input_file_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2862,7 +2862,7 @@ class RemoveSavedAnimationRequest : public RequestOnceActor {
   }
 };
 
-class GetInlineQueryResultsRequest : public RequestOnceActor {
+class GetInlineQueryResultsRequest final : public RequestOnceActor {
   UserId bot_user_id_;
   DialogId dialog_id_;
   Location user_location_;
@@ -2893,7 +2893,7 @@ class GetInlineQueryResultsRequest : public RequestOnceActor {
   }
 };
 
-class GetCallbackQueryAnswerRequest : public RequestOnceActor {
+class GetCallbackQueryAnswerRequest final : public RequestOnceActor {
   FullMessageId full_message_id_;
   tl_object_ptr<td_api::CallbackQueryPayload> payload_;
 
@@ -2925,7 +2925,7 @@ class GetCallbackQueryAnswerRequest : public RequestOnceActor {
   }
 };
 
-class GetSupportUserRequest : public RequestActor<> {
+class GetSupportUserRequest final : public RequestActor<> {
   UserId user_id_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2941,7 +2941,7 @@ class GetSupportUserRequest : public RequestActor<> {
   }
 };
 
-class GetBackgroundsRequest : public RequestOnceActor {
+class GetBackgroundsRequest final : public RequestOnceActor {
   bool for_dark_theme_;
 
   void do_run(Promise<Unit> &&promise) final {
@@ -2958,7 +2958,7 @@ class GetBackgroundsRequest : public RequestOnceActor {
   }
 };
 
-class SearchBackgroundRequest : public RequestActor<> {
+class SearchBackgroundRequest final : public RequestActor<> {
   string name_;
 
   std::pair<BackgroundId, BackgroundType> background_;
@@ -2978,7 +2978,7 @@ class SearchBackgroundRequest : public RequestActor<> {
   }
 };
 
-class SetBackgroundRequest : public RequestActor<> {
+class SetBackgroundRequest final : public RequestActor<> {
   td_api::object_ptr<td_api::InputBackground> input_background_;
   td_api::object_ptr<td_api::BackgroundType> background_type_;
   bool for_dark_theme_ = false;
@@ -4056,7 +4056,7 @@ void Td::close_impl(bool destroy_flag) {
   send_closure_later(actor_id(this), &Td::dec_request_actor_refcnt);  // remove guard
 }
 
-class Td::DownloadFileCallback : public FileManager::DownloadCallback {
+class Td::DownloadFileCallback final : public FileManager::DownloadCallback {
  public:
   void on_progress(FileId file_id) final {
   }
@@ -4070,7 +4070,7 @@ class Td::DownloadFileCallback : public FileManager::DownloadCallback {
   }
 };
 
-class Td::UploadFileCallback : public FileManager::UploadCallback {
+class Td::UploadFileCallback final : public FileManager::UploadCallback {
  public:
   void on_progress(FileId file_id) final {
   }
@@ -4246,7 +4246,7 @@ Status Td::init(DbKey key) {
 
 void Td::init_options_and_network() {
   VLOG(td_init) << "Create StateManager";
-  class StateManagerCallback : public StateManager::Callback {
+  class StateManagerCallback final : public StateManager::Callback {
    public:
     explicit StateManagerCallback(ActorShared<Td> td) : td_(std::move(td)) {
     }
@@ -4298,7 +4298,7 @@ void Td::init_options_and_network() {
   G()->set_config_manager(config_manager_.get());
 
   VLOG(td_init) << "Set ConfigShared callback";
-  class ConfigSharedCallback : public ConfigShared::Callback {
+  class ConfigSharedCallback final : public ConfigShared::Callback {
    public:
     void on_option_updated(const string &name, const string &value) const final {
       send_closure(G()->td(), &Td::on_config_option_updated, name);
@@ -4357,7 +4357,7 @@ void Td::init_file_manager() {
   download_file_callback_ = std::make_shared<DownloadFileCallback>();
   upload_file_callback_ = std::make_shared<UploadFileCallback>();
 
-  class FileManagerContext : public FileManager::Context {
+  class FileManagerContext final : public FileManager::Context {
    public:
     explicit FileManagerContext(Td *td) : td_(td) {
     }
diff --git a/td/telegram/TermsOfService.cpp b/td/telegram/TermsOfService.cpp
index 1201ee9bd..654be4697 100644
--- a/td/telegram/TermsOfService.cpp
+++ b/td/telegram/TermsOfService.cpp
@@ -17,7 +17,7 @@
 
 namespace td {
 
-class GetTermsOfServiceUpdateQuery : public Td::ResultHandler {
+class GetTermsOfServiceUpdateQuery final : public Td::ResultHandler {
   Promise<std::pair<int32, TermsOfService>> promise_;
 
  public:
@@ -58,7 +58,7 @@ class GetTermsOfServiceUpdateQuery : public Td::ResultHandler {
   }
 };
 
-class AcceptTermsOfServiceQuery : public Td::ResultHandler {
+class AcceptTermsOfServiceQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
 
  public:
diff --git a/td/telegram/TopDialogManager.h b/td/telegram/TopDialogManager.h
index ad996abc3..dedb31d13 100644
--- a/td/telegram/TopDialogManager.h
+++ b/td/telegram/TopDialogManager.h
@@ -22,7 +22,7 @@
 
 namespace td {
 
-class TopDialogManager : public NetQueryCallback {
+class TopDialogManager final : public NetQueryCallback {
  public:
   explicit TopDialogManager(ActorShared<> parent) : parent_(std::move(parent)) {
   }
diff --git a/td/telegram/UpdatesManager.cpp b/td/telegram/UpdatesManager.cpp
index 9c8419811..4748242fe 100644
--- a/td/telegram/UpdatesManager.cpp
+++ b/td/telegram/UpdatesManager.cpp
@@ -86,7 +86,7 @@ class OnUpdate {
   }
 };
 
-class GetUpdatesStateQuery : public Td::ResultHandler {
+class GetUpdatesStateQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::updates_state>> promise_;
 
  public:
@@ -112,7 +112,7 @@ class GetUpdatesStateQuery : public Td::ResultHandler {
   }
 };
 
-class PingServerQuery : public Td::ResultHandler {
+class PingServerQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::updates_state>> promise_;
 
  public:
@@ -138,7 +138,7 @@ class PingServerQuery : public Td::ResultHandler {
   }
 };
 
-class GetDifferenceQuery : public Td::ResultHandler {
+class GetDifferenceQuery final : public Td::ResultHandler {
   Promise<tl_object_ptr<telegram_api::updates_Difference>> promise_;
 
  public:
diff --git a/td/telegram/UpdatesManager.h b/td/telegram/UpdatesManager.h
index fee234470..4013dd882 100644
--- a/td/telegram/UpdatesManager.h
+++ b/td/telegram/UpdatesManager.h
@@ -33,7 +33,7 @@ extern int VERBOSITY_NAME(get_difference);
 
 class Td;
 
-class dummyUpdate : public telegram_api::Update {
+class dummyUpdate final : public telegram_api::Update {
  public:
   static constexpr int32 ID = 1234567891;
   int32 get_id() const final {
@@ -54,7 +54,7 @@ class dummyUpdate : public telegram_api::Update {
   }
 };
 
-class updateSentMessage : public telegram_api::Update {
+class updateSentMessage final : public telegram_api::Update {
  public:
   int64 random_id_;
   MessageId message_id_;
@@ -88,7 +88,7 @@ class updateSentMessage : public telegram_api::Update {
   }
 };
 
-class UpdatesManager : public Actor {
+class UpdatesManager final : public Actor {
  public:
   UpdatesManager(Td *td, ActorShared<> parent);
 
diff --git a/td/telegram/WebPageBlock.cpp b/td/telegram/WebPageBlock.cpp
index 791157552..4e7a9068f 100644
--- a/td/telegram/WebPageBlock.cpp
+++ b/td/telegram/WebPageBlock.cpp
@@ -432,7 +432,7 @@ class RelatedArticle {
   }
 };
 
-class WebPageBlockTitle : public WebPageBlock {
+class WebPageBlockTitle final : public WebPageBlock {
   RichText title;
 
  public:
@@ -466,7 +466,7 @@ class WebPageBlockTitle : public WebPageBlock {
   }
 };
 
-class WebPageBlockSubtitle : public WebPageBlock {
+class WebPageBlockSubtitle final : public WebPageBlock {
   RichText subtitle;
 
  public:
@@ -499,7 +499,7 @@ class WebPageBlockSubtitle : public WebPageBlock {
   }
 };
 
-class WebPageBlockAuthorDate : public WebPageBlock {
+class WebPageBlockAuthorDate final : public WebPageBlock {
   RichText author;
   int32 date = 0;
 
@@ -535,7 +535,7 @@ class WebPageBlockAuthorDate : public WebPageBlock {
   }
 };
 
-class WebPageBlockHeader : public WebPageBlock {
+class WebPageBlockHeader final : public WebPageBlock {
   RichText header;
 
  public:
@@ -568,7 +568,7 @@ class WebPageBlockHeader : public WebPageBlock {
   }
 };
 
-class WebPageBlockSubheader : public WebPageBlock {
+class WebPageBlockSubheader final : public WebPageBlock {
   RichText subheader;
 
  public:
@@ -601,7 +601,7 @@ class WebPageBlockSubheader : public WebPageBlock {
   }
 };
 
-class WebPageBlockKicker : public WebPageBlock {
+class WebPageBlockKicker final : public WebPageBlock {
   RichText kicker;
 
  public:
@@ -634,7 +634,7 @@ class WebPageBlockKicker : public WebPageBlock {
   }
 };
 
-class WebPageBlockParagraph : public WebPageBlock {
+class WebPageBlockParagraph final : public WebPageBlock {
   RichText text;
 
  public:
@@ -667,7 +667,7 @@ class WebPageBlockParagraph : public WebPageBlock {
   }
 };
 
-class WebPageBlockPreformatted : public WebPageBlock {
+class WebPageBlockPreformatted final : public WebPageBlock {
   RichText text;
   string language;
 
@@ -703,7 +703,7 @@ class WebPageBlockPreformatted : public WebPageBlock {
   }
 };
 
-class WebPageBlockFooter : public WebPageBlock {
+class WebPageBlockFooter final : public WebPageBlock {
   RichText footer;
 
  public:
@@ -736,7 +736,7 @@ class WebPageBlockFooter : public WebPageBlock {
   }
 };
 
-class WebPageBlockDivider : public WebPageBlock {
+class WebPageBlockDivider final : public WebPageBlock {
  public:
   Type get_type() const final {
     return Type::Divider;
@@ -758,7 +758,7 @@ class WebPageBlockDivider : public WebPageBlock {
   }
 };
 
-class WebPageBlockAnchor : public WebPageBlock {
+class WebPageBlockAnchor final : public WebPageBlock {
   string name;
 
  public:
@@ -793,7 +793,7 @@ class WebPageBlockAnchor : public WebPageBlock {
   }
 };
 
-class WebPageBlockList : public WebPageBlock {
+class WebPageBlockList final : public WebPageBlock {
  public:
   struct Item {
     string label;
@@ -883,7 +883,7 @@ class WebPageBlockList : public WebPageBlock {
   }
 };
 
-class WebPageBlockBlockQuote : public WebPageBlock {
+class WebPageBlockBlockQuote final : public WebPageBlock {
   RichText text;
   RichText credit;
 
@@ -921,7 +921,7 @@ class WebPageBlockBlockQuote : public WebPageBlock {
   }
 };
 
-class WebPageBlockPullQuote : public WebPageBlock {
+class WebPageBlockPullQuote final : public WebPageBlock {
   RichText text;
   RichText credit;
 
@@ -959,7 +959,7 @@ class WebPageBlockPullQuote : public WebPageBlock {
   }
 };
 
-class WebPageBlockAnimation : public WebPageBlock {
+class WebPageBlockAnimation final : public WebPageBlock {
   FileId animation_file_id;
   WebPageBlockCaption caption;
   bool need_autoplay = false;
@@ -1025,7 +1025,7 @@ class WebPageBlockAnimation : public WebPageBlock {
   }
 };
 
-class WebPageBlockPhoto : public WebPageBlock {
+class WebPageBlockPhoto final : public WebPageBlock {
   Photo photo;
   WebPageBlockCaption caption;
   string url;
@@ -1075,7 +1075,7 @@ class WebPageBlockPhoto : public WebPageBlock {
   }
 };
 
-class WebPageBlockVideo : public WebPageBlock {
+class WebPageBlockVideo final : public WebPageBlock {
   FileId video_file_id;
   WebPageBlockCaption caption;
   bool need_autoplay = false;
@@ -1144,7 +1144,7 @@ class WebPageBlockVideo : public WebPageBlock {
   }
 };
 
-class WebPageBlockCover : public WebPageBlock {
+class WebPageBlockCover final : public WebPageBlock {
   unique_ptr<WebPageBlock> cover;
 
  public:
@@ -1177,7 +1177,7 @@ class WebPageBlockCover : public WebPageBlock {
   }
 };
 
-class WebPageBlockEmbedded : public WebPageBlock {
+class WebPageBlockEmbedded final : public WebPageBlock {
   string url;
   string html;
   Photo poster_photo;
@@ -1245,7 +1245,7 @@ class WebPageBlockEmbedded : public WebPageBlock {
   }
 };
 
-class WebPageBlockEmbeddedPost : public WebPageBlock {
+class WebPageBlockEmbeddedPost final : public WebPageBlock {
   string url;
   string author;
   Photo author_photo;
@@ -1306,7 +1306,7 @@ class WebPageBlockEmbeddedPost : public WebPageBlock {
   }
 };
 
-class WebPageBlockCollage : public WebPageBlock {
+class WebPageBlockCollage final : public WebPageBlock {
   vector<unique_ptr<WebPageBlock>> page_blocks;
   WebPageBlockCaption caption;
 
@@ -1347,7 +1347,7 @@ class WebPageBlockCollage : public WebPageBlock {
   }
 };
 
-class WebPageBlockSlideshow : public WebPageBlock {
+class WebPageBlockSlideshow final : public WebPageBlock {
   vector<unique_ptr<WebPageBlock>> page_blocks;
   WebPageBlockCaption caption;
 
@@ -1388,7 +1388,7 @@ class WebPageBlockSlideshow : public WebPageBlock {
   }
 };
 
-class WebPageBlockChatLink : public WebPageBlock {
+class WebPageBlockChatLink final : public WebPageBlock {
   string title;
   DialogPhoto photo;
   string username;
@@ -1429,7 +1429,7 @@ class WebPageBlockChatLink : public WebPageBlock {
   }
 };
 
-class WebPageBlockAudio : public WebPageBlock {
+class WebPageBlockAudio final : public WebPageBlock {
   FileId audio_file_id;
   WebPageBlockCaption caption;
 
@@ -1498,7 +1498,7 @@ class WebPageBlockAudio : public WebPageBlock {
   }
 };
 
-class WebPageBlockTable : public WebPageBlock {
+class WebPageBlockTable final : public WebPageBlock {
   RichText title;
   vector<vector<WebPageBlockTableCell>> cells;
   bool is_bordered = false;
@@ -1556,7 +1556,7 @@ class WebPageBlockTable : public WebPageBlock {
   }
 };
 
-class WebPageBlockDetails : public WebPageBlock {
+class WebPageBlockDetails final : public WebPageBlock {
   RichText header;
   vector<unique_ptr<WebPageBlock>> page_blocks;
   bool is_open;
@@ -1604,7 +1604,7 @@ class WebPageBlockDetails : public WebPageBlock {
   }
 };
 
-class WebPageBlockRelatedArticles : public WebPageBlock {
+class WebPageBlockRelatedArticles final : public WebPageBlock {
   RichText header;
   vector<RelatedArticle> related_articles;
 
@@ -1652,7 +1652,7 @@ class WebPageBlockRelatedArticles : public WebPageBlock {
   }
 };
 
-class WebPageBlockMap : public WebPageBlock {
+class WebPageBlockMap final : public WebPageBlock {
   Location location;
   int32 zoom = 0;
   Dimensions dimensions;
@@ -1696,7 +1696,7 @@ class WebPageBlockMap : public WebPageBlock {
   }
 };
 
-class WebPageBlockVoiceNote : public WebPageBlock {
+class WebPageBlockVoiceNote final : public WebPageBlock {
   FileId voice_note_file_id;
   WebPageBlockCaption caption;
 
diff --git a/td/telegram/WebPagesManager.cpp b/td/telegram/WebPagesManager.cpp
index 0bae16567..bb3195a21 100644
--- a/td/telegram/WebPagesManager.cpp
+++ b/td/telegram/WebPagesManager.cpp
@@ -53,7 +53,7 @@
 
 namespace td {
 
-class GetWebPagePreviewQuery : public Td::ResultHandler {
+class GetWebPagePreviewQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   int64 request_id_;
   string url_;
@@ -92,7 +92,7 @@ class GetWebPagePreviewQuery : public Td::ResultHandler {
   }
 };
 
-class GetWebPageQuery : public Td::ResultHandler {
+class GetWebPageQuery final : public Td::ResultHandler {
   Promise<Unit> promise_;
   WebPageId web_page_id_;
   string url_;
diff --git a/td/telegram/WebPagesManager.h b/td/telegram/WebPagesManager.h
index 96f4b0b47..dff35a444 100644
--- a/td/telegram/WebPagesManager.h
+++ b/td/telegram/WebPagesManager.h
@@ -33,7 +33,7 @@ struct BinlogEvent;
 
 class Td;
 
-class WebPagesManager : public Actor {
+class WebPagesManager final : public Actor {
  public:
   WebPagesManager(Td *td, ActorShared<> parent);
 
diff --git a/td/telegram/cli.cpp b/td/telegram/cli.cpp
index 2da425263..20c30f969 100644
--- a/td/telegram/cli.cpp
+++ b/td/telegram/cli.cpp
@@ -190,7 +190,7 @@ static char **tg_cli_completion(const char *text, int start, int end) {
 }
 #endif
 
-class CliLog : public LogInterface {
+class CliLog final : public LogInterface {
   void do_append(int log_level, CSlice slice) final {
 #ifdef USE_READLINE
     deactivate_readline();
@@ -915,7 +915,7 @@ class CliClient final : public Actor {
     }
 
     LOG(WARNING) << "Creating new TD " << name << " with generation " << generation_ + 1;
-    class TdCallbackImpl : public TdCallback {
+    class TdCallbackImpl final : public TdCallback {
      public:
       TdCallbackImpl(CliClient *client, uint64 generation) : client_(client), generation_(generation) {
       }
@@ -4594,7 +4594,7 @@ void main(int argc, char **argv) {
     ConcurrentScheduler scheduler;
     scheduler.init(3);
 
-    class CreateClient : public Actor {
+    class CreateClient final : public Actor {
      public:
       CreateClient(ConcurrentScheduler *scheduler, bool use_test_dc, bool get_chat_list, bool disable_network,
                    int32 api_id, std::string api_hash)
diff --git a/td/telegram/files/FileDb.cpp b/td/telegram/files/FileDb.cpp
index 99ae0ee07..e9d2ad5ac 100644
--- a/td/telegram/files/FileDb.cpp
+++ b/td/telegram/files/FileDb.cpp
@@ -57,9 +57,9 @@ Status init_file_db(SqliteDb &db, int32 version) {
   return Status::OK();
 }
 
-class FileDb : public FileDbInterface {
+class FileDb final : public FileDbInterface {
  public:
-  class FileDbActor : public Actor {
+  class FileDbActor final : public Actor {
    public:
     FileDbActor(FileDbId current_pmc_id, std::shared_ptr<SqliteKeyValueSafe> file_kv_safe)
         : current_pmc_id_(current_pmc_id), file_kv_safe_(std::move(file_kv_safe)) {
diff --git a/td/telegram/files/FileDownloader.h b/td/telegram/files/FileDownloader.h
index c78e33ccc..bb03cab18 100644
--- a/td/telegram/files/FileDownloader.h
+++ b/td/telegram/files/FileDownloader.h
@@ -23,7 +23,7 @@
 #include <utility>
 
 namespace td {
-class FileDownloader : public FileLoader {
+class FileDownloader final : public FileLoader {
  public:
   class Callback : public FileLoader::Callback {
    public:
diff --git a/td/telegram/files/FileFromBytes.h b/td/telegram/files/FileFromBytes.h
index 7d9125447..73ec0a00e 100644
--- a/td/telegram/files/FileFromBytes.h
+++ b/td/telegram/files/FileFromBytes.h
@@ -18,7 +18,7 @@
 #include "td/utils/Status.h"
 
 namespace td {
-class FileFromBytes : public FileLoaderActor {
+class FileFromBytes final : public FileLoaderActor {
  public:
   class Callback {
    public:
diff --git a/td/telegram/files/FileGcWorker.h b/td/telegram/files/FileGcWorker.h
index ae91fb179..e7e6f8dbc 100644
--- a/td/telegram/files/FileGcWorker.h
+++ b/td/telegram/files/FileGcWorker.h
@@ -24,7 +24,7 @@ struct FileGcResult {
   FileStats removed_file_stats_;
 };
 
-class FileGcWorker : public Actor {
+class FileGcWorker final : public Actor {
  public:
   FileGcWorker(ActorShared<> parent, CancellationToken token) : parent_(std::move(parent)), token_(std::move(token)) {
   }
diff --git a/td/telegram/files/FileGenerateManager.cpp b/td/telegram/files/FileGenerateManager.cpp
index 886bcea99..0af04cb75 100644
--- a/td/telegram/files/FileGenerateManager.cpp
+++ b/td/telegram/files/FileGenerateManager.cpp
@@ -44,7 +44,7 @@ class FileGenerateActor : public Actor {
   virtual void file_generate_finish(Status status, Promise<> promise) = 0;
 };
 
-class FileDownloadGenerateActor : public FileGenerateActor {
+class FileDownloadGenerateActor final : public FileGenerateActor {
  public:
   FileDownloadGenerateActor(FileType file_type, FileId file_id, unique_ptr<FileGenerateCallback> callback,
                             ActorShared<> parent)
@@ -65,7 +65,7 @@ class FileDownloadGenerateActor : public FileGenerateActor {
 
   void start_up() final {
     LOG(INFO) << "Generate by downloading " << file_id_;
-    class Callback : public FileManager::DownloadCallback {
+    class Callback final : public FileManager::DownloadCallback {
      public:
       explicit Callback(ActorId<FileDownloadGenerateActor> parent) : parent_(std::move(parent)) {
       }
@@ -112,7 +112,7 @@ class FileDownloadGenerateActor : public FileGenerateActor {
   }
 };
 
-class MapDownloadGenerateActor : public FileGenerateActor {
+class MapDownloadGenerateActor final : public FileGenerateActor {
  public:
   MapDownloadGenerateActor(string conversion, unique_ptr<FileGenerateCallback> callback, ActorShared<> parent)
       : conversion_(std::move(conversion)), callback_(std::move(callback)), parent_(std::move(parent)) {
@@ -130,7 +130,7 @@ class MapDownloadGenerateActor : public FileGenerateActor {
   ActorShared<> parent_;
   string file_name_;
 
-  class Callback : public NetQueryCallback {
+  class Callback final : public NetQueryCallback {
     ActorId<MapDownloadGenerateActor> parent_;
 
    public:
@@ -236,7 +236,7 @@ class MapDownloadGenerateActor : public FileGenerateActor {
   }
 };
 
-class FileExternalGenerateActor : public FileGenerateActor {
+class FileExternalGenerateActor final : public FileGenerateActor {
  public:
   FileExternalGenerateActor(uint64 query_id, const FullGenerateFileLocation &generate_location,
                             const LocalFileLocation &local_location, string name,
diff --git a/td/telegram/files/FileGenerateManager.h b/td/telegram/files/FileGenerateManager.h
index 7088aaecf..a5063e7b3 100644
--- a/td/telegram/files/FileGenerateManager.h
+++ b/td/telegram/files/FileGenerateManager.h
@@ -31,7 +31,7 @@ class FileGenerateCallback {
   virtual void on_error(Status error) = 0;
 };
 
-class FileGenerateManager : public Actor {
+class FileGenerateManager final : public Actor {
  public:
   explicit FileGenerateManager(ActorShared<> parent) : parent_(std::move(parent)) {
   }
diff --git a/td/telegram/files/FileHashUploader.h b/td/telegram/files/FileHashUploader.h
index 516169f0d..3652cfd2b 100644
--- a/td/telegram/files/FileHashUploader.h
+++ b/td/telegram/files/FileHashUploader.h
@@ -19,7 +19,7 @@
 
 namespace td {
 
-class FileHashUploader : public FileLoaderActor {
+class FileHashUploader final : public FileLoaderActor {
  public:
   class Callback {
    public:
diff --git a/td/telegram/files/FileLoadManager.h b/td/telegram/files/FileLoadManager.h
index 6fa82357e..47fdaf85c 100644
--- a/td/telegram/files/FileLoadManager.h
+++ b/td/telegram/files/FileLoadManager.h
@@ -93,7 +93,7 @@ class FileLoadManager final : public Actor {
   void on_error(Status status);
   void on_error_impl(NodeId node_id, Status status);
 
-  class FileDownloaderCallback : public FileDownloader::Callback {
+  class FileDownloaderCallback final : public FileDownloader::Callback {
    public:
     explicit FileDownloaderCallback(ActorShared<FileLoadManager> actor_id) : actor_id_(std::move(actor_id)) {
     }
@@ -115,7 +115,7 @@ class FileLoadManager final : public Actor {
     }
   };
 
-  class FileUploaderCallback : public FileUploader::Callback {
+  class FileUploaderCallback final : public FileUploader::Callback {
    public:
     explicit FileUploaderCallback(ActorShared<FileLoadManager> actor_id) : actor_id_(std::move(actor_id)) {
     }
@@ -136,7 +136,7 @@ class FileLoadManager final : public Actor {
       send_closure(std::move(actor_id_), &FileLoadManager::on_error, std::move(status));
     }
   };
-  class FileHashUploaderCallback : public FileHashUploader::Callback {
+  class FileHashUploaderCallback final : public FileHashUploader::Callback {
    public:
     explicit FileHashUploaderCallback(ActorShared<FileLoadManager> actor_id) : actor_id_(std::move(actor_id)) {
     }
@@ -152,7 +152,7 @@ class FileLoadManager final : public Actor {
     }
   };
 
-  class FileFromBytesCallback : public FileFromBytes::Callback {
+  class FileFromBytesCallback final : public FileFromBytes::Callback {
    public:
     explicit FileFromBytesCallback(ActorShared<FileLoadManager> actor_id) : actor_id_(std::move(actor_id)) {
     }
diff --git a/td/telegram/files/FileManager.cpp b/td/telegram/files/FileManager.cpp
index e7660c591..85e82c9a6 100644
--- a/td/telegram/files/FileManager.cpp
+++ b/td/telegram/files/FileManager.cpp
@@ -2327,7 +2327,7 @@ void FileManager::run_download(FileNodePtr node, bool force_update_priority) {
                download_limit, priority);
 }
 
-class FileManager::ForceUploadActor : public Actor {
+class FileManager::ForceUploadActor final : public Actor {
  public:
   ForceUploadActor(FileManager *file_manager, FileId file_id, std::shared_ptr<FileManager::UploadCallback> callback,
                    int32 new_priority, uint64 upload_order, bool prefer_small, ActorShared<> parent)
@@ -2351,7 +2351,7 @@ class FileManager::ForceUploadActor : public Actor {
   bool is_active_{false};
   int attempt_{0};
 
-  class UploadCallback : public FileManager::UploadCallback {
+  class UploadCallback final : public FileManager::UploadCallback {
    public:
     explicit UploadCallback(ActorId<ForceUploadActor> callback) : callback_(std::move(callback)) {
     }
@@ -2678,7 +2678,7 @@ void FileManager::run_generate(FileNodePtr node) {
   node->generate_id_ = id;
   send_closure(file_generate_manager_, &FileGenerateManager::generate_file, id, *node->generate_, node->local_,
                node->suggested_path(), [file_manager = this, id] {
-                 class Callback : public FileGenerateCallback {
+                 class Callback final : public FileGenerateCallback {
                    ActorId<FileManager> actor_;
                    uint64 query_id_;
 
diff --git a/td/telegram/files/FileManager.h b/td/telegram/files/FileManager.h
index 857c56442..5d16b5ad3 100644
--- a/td/telegram/files/FileManager.h
+++ b/td/telegram/files/FileManager.h
@@ -341,7 +341,7 @@ class FileView {
   static string get_persistent_id(const FullRemoteFileLocation &location);
 };
 
-class FileManager : public FileLoadManager::Callback {
+class FileManager final : public FileLoadManager::Callback {
  public:
   class DownloadCallback {
    public:
diff --git a/td/telegram/files/FileStatsWorker.h b/td/telegram/files/FileStatsWorker.h
index ff5516f4c..c3f545c02 100644
--- a/td/telegram/files/FileStatsWorker.h
+++ b/td/telegram/files/FileStatsWorker.h
@@ -15,7 +15,7 @@
 
 namespace td {
 
-class FileStatsWorker : public Actor {
+class FileStatsWorker final : public Actor {
  public:
   FileStatsWorker(ActorShared<> parent, CancellationToken token)
       : parent_(std::move(parent)), token_(std::move(token)) {
diff --git a/td/telegram/files/FileUploader.h b/td/telegram/files/FileUploader.h
index 1eea72476..81a89e24d 100644
--- a/td/telegram/files/FileUploader.h
+++ b/td/telegram/files/FileUploader.h
@@ -19,7 +19,7 @@
 
 namespace td {
 
-class FileUploader : public FileLoader {
+class FileUploader final : public FileLoader {
  public:
   class Callback : public FileLoader::Callback {
    public:
diff --git a/td/telegram/files/ResourceManager.h b/td/telegram/files/ResourceManager.h
index 3a2b4a9bc..1fe1753ec 100644
--- a/td/telegram/files/ResourceManager.h
+++ b/td/telegram/files/ResourceManager.h
@@ -18,7 +18,7 @@
 
 namespace td {
 
-class ResourceManager : public Actor {
+class ResourceManager final : public Actor {
  public:
   enum class Mode : int32 { Baseline, Greedy };
   explicit ResourceManager(Mode mode) : mode_(mode) {
@@ -34,7 +34,7 @@ class ResourceManager : public Actor {
  private:
   Mode mode_;
   using NodeId = uint64;
-  struct Node : public HeapNode {
+  struct Node final : public HeapNode {
     NodeId node_id;
 
     ResourceState resource_state_;
diff --git a/td/telegram/logevent/LogEvent.h b/td/telegram/logevent/LogEvent.h
index 1c17dec3e..e8f5195c2 100644
--- a/td/telegram/logevent/LogEvent.h
+++ b/td/telegram/logevent/LogEvent.h
@@ -169,7 +169,7 @@ Result<unique_ptr<DestT>> from_buffer_slice(BufferSlice slice) {
 }
 
 template <class T>
-class StorerImpl : public Storer {
+class StorerImpl final : public Storer {
  public:
   explicit StorerImpl(const T &event) : event_(event) {
   }
@@ -211,7 +211,7 @@ class LogEventBase : public LogEvent {
   }
 };
 
-class LogEventParser : public WithVersion<WithContext<TlParser, Global *>> {
+class LogEventParser final : public WithVersion<WithContext<TlParser, Global *>> {
  public:
   explicit LogEventParser(Slice data) : WithVersion<WithContext<TlParser, Global *>>(data) {
     set_version(fetch_int());
@@ -220,7 +220,7 @@ class LogEventParser : public WithVersion<WithContext<TlParser, Global *>> {
   }
 };
 
-class LogEventStorerCalcLength : public WithContext<TlStorerCalcLength, Global *> {
+class LogEventStorerCalcLength final : public WithContext<TlStorerCalcLength, Global *> {
  public:
   LogEventStorerCalcLength() : WithContext<TlStorerCalcLength, Global *>() {
     store_int(static_cast<int32>(Version::Next) - 1);
@@ -228,7 +228,7 @@ class LogEventStorerCalcLength : public WithContext<TlStorerCalcLength, Global *
   }
 };
 
-class LogEventStorerUnsafe : public WithContext<TlStorerUnsafe, Global *> {
+class LogEventStorerUnsafe final : public WithContext<TlStorerUnsafe, Global *> {
  public:
   explicit LogEventStorerUnsafe(unsigned char *buf) : WithContext<TlStorerUnsafe, Global *>(buf) {
     store_int(static_cast<int32>(Version::Next) - 1);
@@ -237,7 +237,7 @@ class LogEventStorerUnsafe : public WithContext<TlStorerUnsafe, Global *> {
 };
 
 template <class T>
-class LogEventStorerImpl : public Storer {
+class LogEventStorerImpl final : public Storer {
  public:
   explicit LogEventStorerImpl(const T &event) : event_(event) {
   }
diff --git a/td/telegram/logevent/SecretChatEvent.h b/td/telegram/logevent/SecretChatEvent.h
index 3b6872b8d..128070151 100644
--- a/td/telegram/logevent/SecretChatEvent.h
+++ b/td/telegram/logevent/SecretChatEvent.h
@@ -200,7 +200,7 @@ inline StringBuilder &operator<<(StringBuilder &sb, const EncryptedFileLocation
 
 // LogEvents
 // TODO: Qts and SeqNoState could be just Logevents that are updated during regenerate
-class InboundSecretMessage : public SecretChatLogEventBase<InboundSecretMessage> {
+class InboundSecretMessage final : public SecretChatLogEventBase<InboundSecretMessage> {
  public:
   static constexpr Type type = SecretChatEvent::Type::InboundSecretMessage;
 
@@ -301,7 +301,7 @@ class InboundSecretMessage : public SecretChatLogEventBase<InboundSecretMessage>
   }
 };
 
-class OutboundSecretMessage : public SecretChatLogEventBase<OutboundSecretMessage> {
+class OutboundSecretMessage final : public SecretChatLogEventBase<OutboundSecretMessage> {
  public:
   static constexpr Type type = SecretChatEvent::Type::OutboundSecretMessage;
 
@@ -407,7 +407,7 @@ class OutboundSecretMessage : public SecretChatLogEventBase<OutboundSecretMessag
   }
 };
 
-class CloseSecretChat : public SecretChatLogEventBase<CloseSecretChat> {
+class CloseSecretChat final : public SecretChatLogEventBase<CloseSecretChat> {
  public:
   static constexpr Type type = SecretChatEvent::Type::CloseSecretChat;
   int32 chat_id = 0;
@@ -442,7 +442,7 @@ class CloseSecretChat : public SecretChatLogEventBase<CloseSecretChat> {
   }
 };
 
-class CreateSecretChat : public SecretChatLogEventBase<CreateSecretChat> {
+class CreateSecretChat final : public SecretChatLogEventBase<CreateSecretChat> {
  public:
   static constexpr Type type = SecretChatEvent::Type::CreateSecretChat;
   int32 random_id = 0;
diff --git a/td/telegram/net/AuthDataShared.cpp b/td/telegram/net/AuthDataShared.cpp
index a17fee056..2dc28eaca 100644
--- a/td/telegram/net/AuthDataShared.cpp
+++ b/td/telegram/net/AuthDataShared.cpp
@@ -18,7 +18,7 @@
 
 namespace td {
 
-class AuthDataSharedImpl : public AuthDataShared {
+class AuthDataSharedImpl final : public AuthDataShared {
  public:
   AuthDataSharedImpl(DcId dc_id, std::shared_ptr<PublicRsaKeyShared> public_rsa_key, std::shared_ptr<Guard> guard)
       : dc_id_(dc_id), public_rsa_key_(std::move(public_rsa_key)), guard_(std::move(guard)) {
diff --git a/td/telegram/net/ConnectionCreator.cpp b/td/telegram/net/ConnectionCreator.cpp
index 8c466800c..00a0636a6 100644
--- a/td/telegram/net/ConnectionCreator.cpp
+++ b/td/telegram/net/ConnectionCreator.cpp
@@ -747,7 +747,7 @@ ActorOwn<> ConnectionCreator::prepare_connection(IPAddress ip_address, SocketFd
                                                  Promise<ConnectionData> promise) {
   if (proxy.use_socks5_proxy() || proxy.use_http_tcp_proxy() || transport_type.secret.emulate_tls()) {
     VLOG(connections) << "Create new transparent proxy connection " << debug_str;
-    class Callback : public TransparentProxy::Callback {
+    class Callback final : public TransparentProxy::Callback {
      public:
       explicit Callback(Promise<ConnectionData> promise, IPAddress ip_address,
                         unique_ptr<mtproto::RawConnection::StatsCallback> stats_callback, bool use_connection_token,
@@ -1086,7 +1086,7 @@ void ConnectionCreator::update_mtproto_header(const Proxy &proxy) {
 }
 
 void ConnectionCreator::start_up() {
-  class StateCallback : public StateManager::Callback {
+  class StateCallback final : public StateManager::Callback {
    public:
     explicit StateCallback(ActorId<ConnectionCreator> connection_creator)
         : connection_creator_(std::move(connection_creator)) {
diff --git a/td/telegram/net/ConnectionCreator.h b/td/telegram/net/ConnectionCreator.h
index a831f5f99..21537c76b 100644
--- a/td/telegram/net/ConnectionCreator.h
+++ b/td/telegram/net/ConnectionCreator.h
@@ -54,7 +54,7 @@ namespace td {
 
 extern int VERBOSITY_NAME(connections);
 
-class ConnectionCreator : public NetQueryCallback {
+class ConnectionCreator final : public NetQueryCallback {
  public:
   explicit ConnectionCreator(ActorShared<> parent);
   ConnectionCreator(ConnectionCreator &&other);
diff --git a/td/telegram/net/DcAuthManager.cpp b/td/telegram/net/DcAuthManager.cpp
index 9866ab3e6..39f830f16 100644
--- a/td/telegram/net/DcAuthManager.cpp
+++ b/td/telegram/net/DcAuthManager.cpp
@@ -43,7 +43,7 @@ DcAuthManager::DcAuthManager(ActorShared<> parent) {
 
 void DcAuthManager::add_dc(std::shared_ptr<AuthDataShared> auth_data) {
   VLOG(dc) << "Register " << auth_data->dc_id();
-  class Listener : public AuthDataShared::Listener {
+  class Listener final : public AuthDataShared::Listener {
    public:
     explicit Listener(ActorShared<DcAuthManager> dc_manager) : dc_manager_(std::move(dc_manager)) {
     }
diff --git a/td/telegram/net/DcAuthManager.h b/td/telegram/net/DcAuthManager.h
index 310e0eca7..612bf61a9 100644
--- a/td/telegram/net/DcAuthManager.h
+++ b/td/telegram/net/DcAuthManager.h
@@ -23,7 +23,7 @@ namespace td {
 
 extern int VERBOSITY_NAME(dc);
 
-class DcAuthManager : public NetQueryCallback {
+class DcAuthManager final : public NetQueryCallback {
  public:
   explicit DcAuthManager(ActorShared<> parent);
 
diff --git a/td/telegram/net/NetQuery.h b/td/telegram/net/NetQuery.h
index 7a5897f6d..8684e661d 100644
--- a/td/telegram/net/NetQuery.h
+++ b/td/telegram/net/NetQuery.h
@@ -43,7 +43,7 @@ class NetQueryCallback : public Actor {
   virtual void on_result_resendable(NetQueryPtr query, Promise<NetQueryPtr> promise);
 };
 
-class NetQuery : public TsListNode<NetQueryDebug> {
+class NetQuery final : public TsListNode<NetQueryDebug> {
  public:
   NetQuery() = default;
 
@@ -296,7 +296,7 @@ class NetQuery : public TsListNode<NetQueryDebug> {
   int8 priority_{0};
 
   template <class T>
-  struct movable_atomic : public std::atomic<T> {
+  struct movable_atomic final : public std::atomic<T> {
     movable_atomic() = default;
     movable_atomic(T &&x) : std::atomic<T>(std::forward<T>(x)) {
     }
diff --git a/td/telegram/net/NetQueryDelayer.h b/td/telegram/net/NetQueryDelayer.h
index 2e5e056af..c6f5bf68a 100644
--- a/td/telegram/net/NetQueryDelayer.h
+++ b/td/telegram/net/NetQueryDelayer.h
@@ -15,7 +15,7 @@
 
 namespace td {
 
-class NetQueryDelayer : public Actor {
+class NetQueryDelayer final : public Actor {
  public:
   explicit NetQueryDelayer(ActorShared<> parent) : parent_(std::move(parent)) {
   }
diff --git a/td/telegram/net/NetStatsManager.cpp b/td/telegram/net/NetStatsManager.cpp
index d032deac3..ce64866c8 100644
--- a/td/telegram/net/NetStatsManager.cpp
+++ b/td/telegram/net/NetStatsManager.cpp
@@ -48,7 +48,7 @@ static void parse(NetStatsData &net_stats, ParserT &parser) {
 
 void NetStatsManager::init() {
   LOG_CHECK(!empty()) << G()->close_flag();
-  class NetStatsInternalCallback : public NetStats::Callback {
+  class NetStatsInternalCallback final : public NetStats::Callback {
    public:
     NetStatsInternalCallback(ActorId<NetStatsManager> parent, size_t id) : parent_(std::move(parent)), id_(id) {
     }
@@ -232,7 +232,7 @@ void NetStatsManager::start_up() {
     G()->td_db()->get_binlog_pmc()->set("net_stats_since", to_string(since_total_));
   }
 
-  class NetCallback : public StateManager::Callback {
+  class NetCallback final : public StateManager::Callback {
    public:
     explicit NetCallback(ActorId<NetStatsManager> net_stats_manager)
         : net_stats_manager_(std::move(net_stats_manager)) {
diff --git a/td/telegram/net/NetStatsManager.h b/td/telegram/net/NetStatsManager.h
index b1e3891be..98299abbd 100644
--- a/td/telegram/net/NetStatsManager.h
+++ b/td/telegram/net/NetStatsManager.h
@@ -61,7 +61,7 @@ struct NetworkStats {
   }
 };
 
-class NetStatsManager : public Actor {
+class NetStatsManager final : public Actor {
  public:
   explicit NetStatsManager(ActorShared<> parent) : parent_(std::move(parent)) {
   }
diff --git a/td/telegram/net/PublicRsaKeyShared.h b/td/telegram/net/PublicRsaKeyShared.h
index 406272aa5..fc16f23a7 100644
--- a/td/telegram/net/PublicRsaKeyShared.h
+++ b/td/telegram/net/PublicRsaKeyShared.h
@@ -18,7 +18,7 @@
 
 namespace td {
 
-class PublicRsaKeyShared : public PublicRsaKeyInterface {
+class PublicRsaKeyShared final : public PublicRsaKeyInterface {
  public:
   PublicRsaKeyShared(DcId dc_id, bool is_test);
 
diff --git a/td/telegram/net/PublicRsaKeyWatchdog.cpp b/td/telegram/net/PublicRsaKeyWatchdog.cpp
index 5954be555..cd2d054f5 100644
--- a/td/telegram/net/PublicRsaKeyWatchdog.cpp
+++ b/td/telegram/net/PublicRsaKeyWatchdog.cpp
@@ -23,7 +23,7 @@ PublicRsaKeyWatchdog::PublicRsaKeyWatchdog(ActorShared<> parent) : parent_(std::
 }
 
 void PublicRsaKeyWatchdog::add_public_rsa_key(std::shared_ptr<PublicRsaKeyShared> key) {
-  class Listener : public PublicRsaKeyShared::Listener {
+  class Listener final : public PublicRsaKeyShared::Listener {
    public:
     explicit Listener(ActorId<PublicRsaKeyWatchdog> parent) : parent_(std::move(parent)) {
     }
diff --git a/td/telegram/net/PublicRsaKeyWatchdog.h b/td/telegram/net/PublicRsaKeyWatchdog.h
index 202dd366a..632df9d2b 100644
--- a/td/telegram/net/PublicRsaKeyWatchdog.h
+++ b/td/telegram/net/PublicRsaKeyWatchdog.h
@@ -24,7 +24,7 @@
 
 namespace td {
 
-class PublicRsaKeyWatchdog : public NetActor {
+class PublicRsaKeyWatchdog final : public NetActor {
  public:
   explicit PublicRsaKeyWatchdog(ActorShared<> parent);
 
diff --git a/td/telegram/net/Session.cpp b/td/telegram/net/Session.cpp
index aac29d2ea..b0e628ba7 100644
--- a/td/telegram/net/Session.cpp
+++ b/td/telegram/net/Session.cpp
@@ -47,7 +47,7 @@ namespace td {
 
 namespace detail {
 
-class GenAuthKeyActor : public Actor {
+class GenAuthKeyActor final : public Actor {
  public:
   GenAuthKeyActor(Slice name, unique_ptr<mtproto::AuthKeyHandshake> handshake,
                   unique_ptr<mtproto::AuthKeyHandshakeContext> context,
@@ -190,7 +190,7 @@ bool Session::can_destroy_auth_key() const {
 }
 
 void Session::start_up() {
-  class StateCallback : public StateManager::Callback {
+  class StateCallback final : public StateManager::Callback {
    public:
     explicit StateCallback(ActorId<Session> session) : session_(std::move(session)) {
     }
@@ -1254,7 +1254,7 @@ void Session::create_gen_auth_key_actor(HandshakeId handshake_id) {
   if (!info.handshake_) {
     info.handshake_ = make_unique<mtproto::AuthKeyHandshake>(dc_id_, is_main && !is_cdn_ ? 0 : 24 * 60 * 60);
   }
-  class AuthKeyHandshakeContext : public mtproto::AuthKeyHandshakeContext {
+  class AuthKeyHandshakeContext final : public mtproto::AuthKeyHandshakeContext {
    public:
     AuthKeyHandshakeContext(DhCallback *dh_callback, std::shared_ptr<PublicRsaKeyInterface> public_rsa_key)
         : dh_callback_(dh_callback), public_rsa_key_(std::move(public_rsa_key)) {
diff --git a/td/telegram/net/Session.h b/td/telegram/net/Session.h
index f072fe0f5..32776fd6d 100644
--- a/td/telegram/net/Session.h
+++ b/td/telegram/net/Session.h
@@ -76,7 +76,7 @@ class Session final
   void close();
 
  private:
-  struct Query : private ListNode {
+  struct Query final : private ListNode {
     uint64 container_id;
     NetQueryPtr query;
 
diff --git a/td/telegram/net/SessionMultiProxy.cpp b/td/telegram/net/SessionMultiProxy.cpp
index b6141a923..5308aef7d 100644
--- a/td/telegram/net/SessionMultiProxy.cpp
+++ b/td/telegram/net/SessionMultiProxy.cpp
@@ -126,7 +126,7 @@ void SessionMultiProxy::init() {
                             << format::cond(session_count_ > 1, format::concat("#", i));
 
     SessionInfo info;
-    class Callback : public SessionProxy::Callback {
+    class Callback final : public SessionProxy::Callback {
      public:
       Callback(ActorId<SessionMultiProxy> parent, uint32 generation, int32 session_id)
           : parent_(parent), generation_(generation), session_id_(session_id) {
diff --git a/td/telegram/net/SessionMultiProxy.h b/td/telegram/net/SessionMultiProxy.h
index bd63220f0..8208c3d24 100644
--- a/td/telegram/net/SessionMultiProxy.h
+++ b/td/telegram/net/SessionMultiProxy.h
@@ -17,7 +17,7 @@ namespace td {
 
 class SessionProxy;
 
-class SessionMultiProxy : public Actor {
+class SessionMultiProxy final : public Actor {
  public:
   SessionMultiProxy();
   SessionMultiProxy(const SessionMultiProxy &other) = delete;
diff --git a/td/telegram/net/SessionProxy.cpp b/td/telegram/net/SessionProxy.cpp
index 7c1a0e1bb..b8c04f50f 100644
--- a/td/telegram/net/SessionProxy.cpp
+++ b/td/telegram/net/SessionProxy.cpp
@@ -28,7 +28,7 @@ namespace mtproto {
 class RawConnection;
 }  // namespace mtproto
 
-class SessionCallback : public Session::Callback {
+class SessionCallback final : public Session::Callback {
  public:
   SessionCallback(ActorShared<SessionProxy> parent, DcId dc_id, bool allow_media_only, bool is_media, size_t hash)
       : parent_(std::move(parent))
@@ -88,7 +88,7 @@ SessionProxy::SessionProxy(unique_ptr<Callback> callback, std::shared_ptr<AuthDa
 }
 
 void SessionProxy::start_up() {
-  class Listener : public AuthDataShared::Listener {
+  class Listener final : public AuthDataShared::Listener {
    public:
     explicit Listener(ActorShared<SessionProxy> session_proxy) : session_proxy_(std::move(session_proxy)) {
     }
diff --git a/td/telegram/net/SessionProxy.h b/td/telegram/net/SessionProxy.h
index f2db0ba7a..fef984f9d 100644
--- a/td/telegram/net/SessionProxy.h
+++ b/td/telegram/net/SessionProxy.h
@@ -20,7 +20,7 @@ namespace td {
 
 class Session;
 
-class SessionProxy : public Actor {
+class SessionProxy final : public Actor {
  public:
   friend class SessionCallback;
   class Callback {
diff --git a/td/telegram/net/TempAuthKeyWatchdog.h b/td/telegram/net/TempAuthKeyWatchdog.h
index b9384cb5b..388ae97d3 100644
--- a/td/telegram/net/TempAuthKeyWatchdog.h
+++ b/td/telegram/net/TempAuthKeyWatchdog.h
@@ -23,7 +23,7 @@
 
 namespace td {
 
-class TempAuthKeyWatchdog : public NetQueryCallback {
+class TempAuthKeyWatchdog final : public NetQueryCallback {
   class RegisteredAuthKeyImpl {
    public:
     explicit RegisteredAuthKeyImpl(int64 auth_key_id)
diff --git a/td/tl/tl_json.h b/td/tl/tl_json.h
index 4aa7daefc..2c77c8a9b 100644
--- a/td/tl/tl_json.h
+++ b/td/tl/tl_json.h
@@ -150,7 +150,7 @@ Status from_json(std::vector<T> &to, JsonValue from) {
 }
 
 template <class T>
-class DowncastHelper : public T {
+class DowncastHelper final : public T {
  public:
   explicit DowncastHelper(int32 constructor) : constructor_(constructor) {
   }
diff --git a/tdactor/example/example.cpp b/tdactor/example/example.cpp
index a58ad96ab..119d18d94 100644
--- a/tdactor/example/example.cpp
+++ b/tdactor/example/example.cpp
@@ -10,14 +10,14 @@
 #include "td/utils/logging.h"
 #include "td/utils/Time.h"
 
-class Worker : public td::Actor {
+class Worker final : public td::Actor {
  public:
   void ping(int x) {
     LOG(ERROR) << "Got ping " << x;
   }
 };
 
-class MainActor : public td::Actor {
+class MainActor final : public td::Actor {
  public:
   void start_up() final {
     LOG(ERROR) << "Start up";
diff --git a/tdactor/td/actor/ConcurrentScheduler.h b/tdactor/td/actor/ConcurrentScheduler.h
index a6ce6a916..e940e632c 100644
--- a/tdactor/td/actor/ConcurrentScheduler.h
+++ b/tdactor/td/actor/ConcurrentScheduler.h
@@ -24,7 +24,7 @@
 
 namespace td {
 
-class ConcurrentScheduler : private Scheduler::Callback {
+class ConcurrentScheduler final : private Scheduler::Callback {
  public:
   void init(int32 threads_n);
 
diff --git a/tdactor/td/actor/MultiPromise.h b/tdactor/td/actor/MultiPromise.h
index 8c69996ec..630a689ad 100644
--- a/tdactor/td/actor/MultiPromise.h
+++ b/tdactor/td/actor/MultiPromise.h
@@ -30,7 +30,7 @@ class MultiPromiseInterface {
   virtual ~MultiPromiseInterface() = default;
 };
 
-class MultiPromise : public MultiPromiseInterface {
+class MultiPromise final : public MultiPromiseInterface {
  public:
   void add_promise(Promise<> &&promise) final {
     impl_->add_promise(std::move(promise));
@@ -91,7 +91,7 @@ class MultiPromiseActor final
   }
 };
 
-class MultiPromiseActorSafe : public MultiPromiseInterface {
+class MultiPromiseActorSafe final : public MultiPromiseInterface {
  public:
   void add_promise(Promise<Unit> &&promise) final;
   Promise<Unit> get_promise() final;
diff --git a/tdactor/td/actor/PromiseFuture.h b/tdactor/td/actor/PromiseFuture.h
index cdd968130..92b3df822 100644
--- a/tdactor/td/actor/PromiseFuture.h
+++ b/tdactor/td/actor/PromiseFuture.h
@@ -69,7 +69,7 @@ class PromiseInterface {
 namespace detail {
 
 template <typename T>
-struct GetArg : public GetArg<decltype(&T::operator())> {};
+struct GetArg final : public GetArg<decltype(&T::operator())> {};
 
 template <class C, class R, class Arg>
 class GetArg<R (C::*)(Arg)> {
@@ -368,7 +368,7 @@ Promise<T> &Promise<T>::operator=(SafePromise<T> &&other) {
 
 namespace detail {
 
-class EventPromise : public PromiseInterface<Unit> {
+class EventPromise final : public PromiseInterface<Unit> {
  public:
   void set_value(Unit &&) final {
     ok_.try_emit();
@@ -407,7 +407,7 @@ class EventPromise : public PromiseInterface<Unit> {
 };
 
 template <class PromiseT>
-class CancellablePromise : public PromiseT {
+class CancellablePromise final : public PromiseT {
  public:
   template <class... ArgsT>
   CancellablePromise(CancellationToken cancellation_token, ArgsT &&... args)
@@ -425,7 +425,7 @@ class CancellablePromise : public PromiseT {
 };
 
 template <class... ArgsT>
-class JoinPromise : public PromiseInterface<Unit> {
+class JoinPromise final : public PromiseInterface<Unit> {
  public:
   explicit JoinPromise(ArgsT &&... arg) : promises_(std::forward<ArgsT>(arg)...) {
   }
diff --git a/tdactor/td/actor/SleepActor.h b/tdactor/td/actor/SleepActor.h
index 9eab389e7..659db5f1a 100644
--- a/tdactor/td/actor/SleepActor.h
+++ b/tdactor/td/actor/SleepActor.h
@@ -13,7 +13,7 @@
 
 namespace td {
 
-class SleepActor : public Actor {
+class SleepActor final : public Actor {
  public:
   SleepActor(double timeout, Promise<> promise) : timeout_(timeout), promise_(std::move(promise)) {
   }
diff --git a/tdactor/td/actor/Timeout.h b/tdactor/td/actor/Timeout.h
index f1407edf2..de4216546 100644
--- a/tdactor/td/actor/Timeout.h
+++ b/tdactor/td/actor/Timeout.h
@@ -69,7 +69,7 @@ class Timeout final : public Actor {
 
 // TODO optimize
 class MultiTimeout final : public Actor {
-  struct Item : public HeapNode {
+  struct Item final : public HeapNode {
     int64 key;
 
     explicit Item(int64 key) : key(key) {
diff --git a/tdactor/td/actor/impl/Event.h b/tdactor/td/actor/impl/Event.h
index 293d9933d..30d55d6f7 100644
--- a/tdactor/td/actor/impl/Event.h
+++ b/tdactor/td/actor/impl/Event.h
@@ -57,7 +57,7 @@ class CustomEvent {
 };
 
 template <class ClosureT>
-class ClosureEvent : public CustomEvent {
+class ClosureEvent final : public CustomEvent {
  public:
   void run(Actor *actor) final {
     closure_.run(static_cast<typename ClosureT::ActorType *>(actor));
@@ -88,7 +88,7 @@ class ClosureEvent : public CustomEvent {
 };
 
 template <class LambdaT>
-class LambdaEvent : public CustomEvent {
+class LambdaEvent final : public CustomEvent {
  public:
   void run(Actor *actor) final {
     f_();
diff --git a/tdactor/test/actors_bugs.cpp b/tdactor/test/actors_bugs.cpp
index dca054a60..683f1f74f 100644
--- a/tdactor/test/actors_bugs.cpp
+++ b/tdactor/test/actors_bugs.cpp
@@ -51,7 +51,7 @@ TEST(MultiTimeout, bug) {
   sched.finish();
 }
 
-class TimeoutManager : public Actor {
+class TimeoutManager final : public Actor {
  public:
   static int32 count;
 
diff --git a/tdactor/test/actors_main.cpp b/tdactor/test/actors_main.cpp
index edf2ee0df..aed69d216 100644
--- a/tdactor/test/actors_main.cpp
+++ b/tdactor/test/actors_main.cpp
@@ -182,7 +182,7 @@ class QueryActor final : public Actor {
 };
 
 class MainQueryActor final : public Actor {
-  class QueryActorCallback : public QueryActor::Callback {
+  class QueryActorCallback final : public QueryActor::Callback {
    public:
     void on_result(Query &&query) final {
       if (query.ready()) {
@@ -342,9 +342,9 @@ class SimpleActor final : public Actor {
 };
 }  // namespace
 
-class SendToDead : public Actor {
+class SendToDead final : public Actor {
  public:
-  class Parent : public Actor {
+  class Parent final : public Actor {
    public:
     explicit Parent(ActorShared<> parent, int ttl = 3) : parent_(std::move(parent)), ttl_(ttl) {
     }
@@ -439,7 +439,7 @@ TEST(Actors, main) {
   sched.finish();
 }
 
-class DoAfterStop : public Actor {
+class DoAfterStop final : public Actor {
  public:
   void loop() final {
     ptr = make_unique<int>(10);
@@ -467,7 +467,7 @@ TEST(Actors, do_after_stop) {
   sched.finish();
 }
 
-class XContext : public ActorContext {
+class XContext final : public ActorContext {
  public:
   int32 get_id() const final {
     return 123456789;
@@ -482,7 +482,7 @@ class XContext : public ActorContext {
   int x = 1234;
 };
 
-class WithXContext : public Actor {
+class WithXContext final : public Actor {
  public:
   void start_up() final {
     auto old_context = set_context(std::make_shared<XContext>());
diff --git a/tdactor/test/actors_simple.cpp b/tdactor/test/actors_simple.cpp
index 247b87beb..f360bde30 100644
--- a/tdactor/test/actors_simple.cpp
+++ b/tdactor/test/actors_simple.cpp
@@ -50,7 +50,7 @@ TEST(Actors, SendLater) {
   scheduler.init(0, {create_queue()}, nullptr);
 
   auto guard = scheduler.get_guard();
-  class Worker : public Actor {
+  class Worker final : public Actor {
    public:
     void f() {
       sb << "A";
@@ -327,7 +327,7 @@ class MsgActor : public Actor {
   virtual void msg() = 0;
 };
 
-class Slave : public Actor {
+class Slave final : public Actor {
  public:
   ActorId<MsgActor> msg;
   explicit Slave(ActorId<MsgActor> msg) : msg(msg) {
@@ -337,7 +337,7 @@ class Slave : public Actor {
   }
 };
 
-class MasterActor : public MsgActor {
+class MasterActor final : public MsgActor {
  public:
   void loop() final {
     alive_ = true;
@@ -372,7 +372,7 @@ TEST(Actors, call_after_destruct) {
   scheduler.run(Timestamp::now());
 }
 
-class LinkTokenSlave : public Actor {
+class LinkTokenSlave final : public Actor {
  public:
   explicit LinkTokenSlave(ActorShared<> parent) : parent_(std::move(parent)) {
   }
@@ -387,7 +387,7 @@ class LinkTokenSlave : public Actor {
   ActorShared<> parent_;
 };
 
-class LinkTokenMasterActor : public Actor {
+class LinkTokenMasterActor final : public Actor {
  public:
   explicit LinkTokenMasterActor(int cnt) : cnt_(cnt) {
   }
@@ -458,7 +458,7 @@ TEST(Actors, promise) {
   ASSERT_EQ(1, value);
 }
 
-class LaterSlave : public Actor {
+class LaterSlave final : public Actor {
  public:
   explicit LaterSlave(ActorShared<> parent) : parent_(std::move(parent)) {
   }
@@ -476,7 +476,7 @@ class LaterSlave : public Actor {
   }
 };
 
-class LaterMasterActor : public Actor {
+class LaterMasterActor final : public Actor {
   int cnt_ = 3;
   std::vector<ActorOwn<LaterSlave>> children_;
   void start_up() final {
@@ -509,7 +509,7 @@ TEST(Actors, later) {
   ASSERT_STREQ(sb.as_cslice().c_str(), "AAABBB");
 }
 
-class MultiPromise2 : public Actor {
+class MultiPromise2 final : public Actor {
  public:
   void start_up() final {
     auto promise = PromiseCreator::lambda([](Result<Unit> result) {
@@ -525,7 +525,7 @@ class MultiPromise2 : public Actor {
   }
 };
 
-class MultiPromise1 : public Actor {
+class MultiPromise1 final : public Actor {
  public:
   void start_up() final {
     auto promise = PromiseCreator::lambda([](Result<Unit> result) {
@@ -549,7 +549,7 @@ TEST(Actors, MultiPromise) {
   scheduler.finish();
 }
 
-class FastPromise : public Actor {
+class FastPromise final : public Actor {
  public:
   void start_up() final {
     PromiseFuture<int> pf;
@@ -573,7 +573,7 @@ TEST(Actors, FastPromise) {
   scheduler.finish();
 }
 
-class StopInTeardown : public Actor {
+class StopInTeardown final : public Actor {
   void loop() final {
     stop();
   }
@@ -595,7 +595,7 @@ TEST(Actors, stop_in_teardown) {
   scheduler.finish();
 }
 
-class AlwaysWaitForMailbox : public Actor {
+class AlwaysWaitForMailbox final : public Actor {
  public:
   void start_up() final {
     always_wait_for_mailbox();
@@ -637,7 +637,7 @@ TEST(Actors, send_from_other_threads) {
   ConcurrentScheduler scheduler;
   scheduler.init(1);
   int thread_n = 10;
-  class Listener : public Actor {
+  class Listener final : public Actor {
    public:
     explicit Listener(int cnt) : cnt_(cnt) {
     }
diff --git a/tdactor/test/actors_workers.cpp b/tdactor/test/actors_workers.cpp
index 43a44aad5..30492834c 100644
--- a/tdactor/test/actors_workers.cpp
+++ b/tdactor/test/actors_workers.cpp
@@ -56,7 +56,7 @@ class Manager final : public Actor {
       , query_size_(query_size) {
   }
 
-  class Callback : public PowerWorker::Callback {
+  class Callback final : public PowerWorker::Callback {
    public:
     Callback(ActorId<Manager> actor_id, int worker_id) : actor_id_(actor_id), worker_id_(worker_id) {
     }
diff --git a/tddb/td/db/BinlogKeyValue.h b/tddb/td/db/BinlogKeyValue.h
index b74aadef6..010f6d808 100644
--- a/tddb/td/db/BinlogKeyValue.h
+++ b/tddb/td/db/BinlogKeyValue.h
@@ -31,11 +31,11 @@
 namespace td {
 
 template <class BinlogT>
-class BinlogKeyValue : public KeyValueSyncInterface {
+class BinlogKeyValue final : public KeyValueSyncInterface {
  public:
   static constexpr int32 MAGIC = 0x2a280000;
 
-  struct Event : public Storer {
+  struct Event final : public Storer {
     Event() = default;
     Event(Slice key, Slice value) : key(key), value(value) {
     }
diff --git a/tddb/td/db/SqliteKeyValueAsync.cpp b/tddb/td/db/SqliteKeyValueAsync.cpp
index 08a3056ce..5f594e488 100644
--- a/tddb/td/db/SqliteKeyValueAsync.cpp
+++ b/tddb/td/db/SqliteKeyValueAsync.cpp
@@ -18,7 +18,7 @@
 
 namespace td {
 
-class SqliteKeyValueAsync : public SqliteKeyValueAsyncInterface {
+class SqliteKeyValueAsync final : public SqliteKeyValueAsyncInterface {
  public:
   explicit SqliteKeyValueAsync(std::shared_ptr<SqliteKeyValueSafe> kv_safe, int32 scheduler_id = -1) {
     impl_ = create_actor_on_scheduler<Impl>("KV", scheduler_id, std::move(kv_safe));
@@ -40,7 +40,7 @@ class SqliteKeyValueAsync : public SqliteKeyValueAsyncInterface {
   }
 
  private:
-  class Impl : public Actor {
+  class Impl final : public Actor {
    public:
     explicit Impl(std::shared_ptr<SqliteKeyValueSafe> kv_safe) : kv_safe_(std::move(kv_safe)) {
     }
diff --git a/tddb/td/db/TQueue.cpp b/tddb/td/db/TQueue.cpp
index 0534c29af..70095eb93 100644
--- a/tddb/td/db/TQueue.cpp
+++ b/tddb/td/db/TQueue.cpp
@@ -80,7 +80,7 @@ bool EventId::is_valid_id(int32 id) {
   return 0 <= id && id < MAX_ID;
 }
 
-class TQueueImpl : public TQueue {
+class TQueueImpl final : public TQueue {
   static constexpr size_t MAX_EVENT_LENGTH = 65536 * 8;
   static constexpr size_t MAX_QUEUE_EVENTS = 1000000;
   static constexpr size_t MAX_TOTAL_EVENT_LENGTH = 1 << 30;
@@ -383,7 +383,7 @@ unique_ptr<TQueue> TQueue::create() {
   return make_unique<TQueueImpl>();
 }
 
-struct TQueueLogEvent : public Storer {
+struct TQueueLogEvent final : public Storer {
   int64 queue_id;
   int32 event_id;
   int32 expires_at;
diff --git a/tddb/td/db/TQueue.h b/tddb/td/db/TQueue.h
index 76284af63..6301e20ba 100644
--- a/tddb/td/db/TQueue.h
+++ b/tddb/td/db/TQueue.h
@@ -122,7 +122,7 @@ StringBuilder &operator<<(StringBuilder &string_builder, const TQueue::EventId i
 struct BinlogEvent;
 
 template <class BinlogT>
-class TQueueBinlog : public TQueue::StorageCallback {
+class TQueueBinlog final : public TQueue::StorageCallback {
  public:
   uint64 push(QueueId queue_id, const RawEvent &event) final;
   void pop(uint64 log_event_id) final;
@@ -138,7 +138,7 @@ class TQueueBinlog : public TQueue::StorageCallback {
   static constexpr int32 BINLOG_EVENT_TYPE = 2314;
 };
 
-class TQueueMemoryStorage : public TQueue::StorageCallback {
+class TQueueMemoryStorage final : public TQueue::StorageCallback {
  public:
   uint64 push(QueueId queue_id, const RawEvent &event) final;
   void pop(uint64 log_event_id) final;
diff --git a/tddb/td/db/binlog/ConcurrentBinlog.cpp b/tddb/td/db/binlog/ConcurrentBinlog.cpp
index 7c3513172..ff0385603 100644
--- a/tddb/td/db/binlog/ConcurrentBinlog.cpp
+++ b/tddb/td/db/binlog/ConcurrentBinlog.cpp
@@ -15,7 +15,7 @@
 
 namespace td {
 namespace detail {
-class BinlogActor : public Actor {
+class BinlogActor final : public Actor {
  public:
   BinlogActor(unique_ptr<Binlog> binlog, uint64 seq_no) : binlog_(std::move(binlog)), processor_(seq_no) {
   }
diff --git a/tddb/td/db/binlog/ConcurrentBinlog.h b/tddb/td/db/binlog/ConcurrentBinlog.h
index 961a83b98..876572e05 100644
--- a/tddb/td/db/binlog/ConcurrentBinlog.h
+++ b/tddb/td/db/binlog/ConcurrentBinlog.h
@@ -27,7 +27,7 @@ namespace detail {
 class BinlogActor;
 }  // namespace detail
 
-class ConcurrentBinlog : public BinlogInterface {
+class ConcurrentBinlog final : public BinlogInterface {
  public:
   using Callback = std::function<void(const BinlogEvent &)>;
   Result<BinlogInfo> init(string path, const Callback &callback, DbKey db_key = DbKey::empty(),
diff --git a/tdnet/td/net/GetHostByNameActor.cpp b/tdnet/td/net/GetHostByNameActor.cpp
index c1f944c31..227780287 100644
--- a/tdnet/td/net/GetHostByNameActor.cpp
+++ b/tdnet/td/net/GetHostByNameActor.cpp
@@ -21,7 +21,7 @@
 namespace td {
 namespace detail {
 
-class GoogleDnsResolver : public Actor {
+class GoogleDnsResolver final : public Actor {
  public:
   GoogleDnsResolver(std::string host, bool prefer_ipv6, Promise<IPAddress> promise)
       : host_(std::move(host)), prefer_ipv6_(prefer_ipv6), promise_(std::move(promise)) {
@@ -86,7 +86,7 @@ class GoogleDnsResolver : public Actor {
   }
 };
 
-class NativeDnsResolver : public Actor {
+class NativeDnsResolver final : public Actor {
  public:
   NativeDnsResolver(std::string host, bool prefer_ipv6, Promise<IPAddress> promise)
       : host_(std::move(host)), prefer_ipv6_(prefer_ipv6), promise_(std::move(promise)) {
diff --git a/tdnet/td/net/HttpProxy.h b/tdnet/td/net/HttpProxy.h
index 613dfc513..3604af43b 100644
--- a/tdnet/td/net/HttpProxy.h
+++ b/tdnet/td/net/HttpProxy.h
@@ -12,7 +12,7 @@
 
 namespace td {
 
-class HttpProxy : public TransparentProxy {
+class HttpProxy final : public TransparentProxy {
  public:
   using TransparentProxy::TransparentProxy;
 
diff --git a/tdnet/td/net/NetStats.h b/tdnet/td/net/NetStats.h
index d3cc0ba4b..71478b025 100644
--- a/tdnet/td/net/NetStats.h
+++ b/tdnet/td/net/NetStats.h
@@ -91,7 +91,7 @@ class NetStats {
   }
 
  private:
-  class Impl : public NetStatsCallback {
+  class Impl final : public NetStatsCallback {
    public:
     NetStatsData get_stats() const {
       NetStatsData res;
diff --git a/tdnet/td/net/Socks5.h b/tdnet/td/net/Socks5.h
index 97531011f..3ad30eed2 100644
--- a/tdnet/td/net/Socks5.h
+++ b/tdnet/td/net/Socks5.h
@@ -12,7 +12,7 @@
 
 namespace td {
 
-class Socks5 : public TransparentProxy {
+class Socks5 final : public TransparentProxy {
  public:
   using TransparentProxy::TransparentProxy;
 
diff --git a/tdnet/td/net/SslStream.cpp b/tdnet/td/net/SslStream.cpp
index 8d43c43a0..b9061b94d 100644
--- a/tdnet/td/net/SslStream.cpp
+++ b/tdnet/td/net/SslStream.cpp
@@ -384,7 +384,7 @@ class SslStreamImpl {
     return size;
   }
 
-  class SslReadByteFlow : public ByteFlowBase {
+  class SslReadByteFlow final : public ByteFlowBase {
    public:
     explicit SslReadByteFlow(SslStreamImpl *stream) : stream_(stream) {
     }
@@ -411,7 +411,7 @@ class SslStreamImpl {
     SslStreamImpl *stream_;
   };
 
-  class SslWriteByteFlow : public ByteFlowBase {
+  class SslWriteByteFlow final : public ByteFlowBase {
    public:
     explicit SslWriteByteFlow(SslStreamImpl *stream) : stream_(stream) {
     }
diff --git a/tdnet/td/net/Wget.h b/tdnet/td/net/Wget.h
index 4f22a085e..723efda12 100644
--- a/tdnet/td/net/Wget.h
+++ b/tdnet/td/net/Wget.h
@@ -20,7 +20,7 @@
 
 namespace td {
 
-class Wget : public HttpOutboundConnection::Callback {
+class Wget final : public HttpOutboundConnection::Callback {
  public:
   explicit Wget(Promise<unique_ptr<HttpQuery>> promise, string url, std::vector<std::pair<string, string>> headers = {},
                 int32 timeout_in = 10, int32 ttl = 3, bool prefer_ipv6 = false,
diff --git a/tdutils/td/utils/AesCtrByteFlow.h b/tdutils/td/utils/AesCtrByteFlow.h
index f8143e10f..130a4284b 100644
--- a/tdutils/td/utils/AesCtrByteFlow.h
+++ b/tdutils/td/utils/AesCtrByteFlow.h
@@ -16,7 +16,7 @@
 namespace td {
 
 #if TD_HAVE_OPENSSL
-class AesCtrByteFlow : public ByteFlowInplaceBase {
+class AesCtrByteFlow final : public ByteFlowInplaceBase {
  public:
   void init(const UInt256 &key, const UInt128 &iv) {
     state_.init(as_slice(key), as_slice(iv));
diff --git a/tdutils/td/utils/BufferedFd.h b/tdutils/td/utils/BufferedFd.h
index cd092ea55..12fdbe1d1 100644
--- a/tdutils/td/utils/BufferedFd.h
+++ b/tdutils/td/utils/BufferedFd.h
@@ -54,7 +54,7 @@ class BufferedFdBase : public FdT {
 };
 
 template <class FdT>
-class BufferedFd : public BufferedFdBase<FdT> {
+class BufferedFd final : public BufferedFdBase<FdT> {
   using Parent = BufferedFdBase<FdT>;
   ChainBufferWriter input_writer_;
   ChainBufferReader input_reader_;
diff --git a/tdutils/td/utils/BufferedUdp.h b/tdutils/td/utils/BufferedUdp.h
index b99815baa..a4b13446e 100644
--- a/tdutils/td/utils/BufferedUdp.h
+++ b/tdutils/td/utils/BufferedUdp.h
@@ -108,7 +108,7 @@ class UdpReader {
 
 #endif
 
-class BufferedUdp : public UdpSocketFd {
+class BufferedUdp final : public UdpSocketFd {
  public:
   explicit BufferedUdp(UdpSocketFd fd) : UdpSocketFd(std::move(fd)) {
   }
diff --git a/tdutils/td/utils/ByteFlow.h b/tdutils/td/utils/ByteFlow.h
index fac133089..ec67f13d7 100644
--- a/tdutils/td/utils/ByteFlow.h
+++ b/tdutils/td/utils/ByteFlow.h
@@ -220,7 +220,7 @@ inline ByteFlowInterface &operator>>(ByteFlowInterface &from, ByteFlowInterface
   return to;
 }
 
-class ByteFlowSource : public ByteFlowInterface {
+class ByteFlowSource final : public ByteFlowInterface {
  public:
   ByteFlowSource() = default;
   explicit ByteFlowSource(ChainBufferReader *buffer) : buffer_(buffer) {
@@ -279,7 +279,7 @@ class ByteFlowSource : public ByteFlowInterface {
   ByteFlowInterface *parent_ = nullptr;
 };
 
-class ByteFlowSink : public ByteFlowInterface {
+class ByteFlowSink final : public ByteFlowInterface {
  public:
   void set_input(ChainBufferReader *input) final {
     CHECK(buffer_ == nullptr);
@@ -329,7 +329,7 @@ class ByteFlowSink : public ByteFlowInterface {
   ChainBufferReader *buffer_ = nullptr;
 };
 
-class ByteFlowMoveSink : public ByteFlowInterface {
+class ByteFlowMoveSink final : public ByteFlowInterface {
  public:
   ByteFlowMoveSink() = default;
   explicit ByteFlowMoveSink(ChainBufferWriter *output) {
diff --git a/tdutils/td/utils/CombinedLog.h b/tdutils/td/utils/CombinedLog.h
index d8ae953b4..fdb1c160e 100644
--- a/tdutils/td/utils/CombinedLog.h
+++ b/tdutils/td/utils/CombinedLog.h
@@ -13,7 +13,7 @@
 
 namespace td {
 
-class CombinedLog : public LogInterface {
+class CombinedLog final : public LogInterface {
  public:
   void set_first(LogInterface *first) {
     first_ = first;
diff --git a/tdutils/td/utils/Destructor.h b/tdutils/td/utils/Destructor.h
index 81df89adf..50b655094 100644
--- a/tdutils/td/utils/Destructor.h
+++ b/tdutils/td/utils/Destructor.h
@@ -24,7 +24,7 @@ class Destructor {
 };
 
 template <class F>
-class LambdaDestructor : public Destructor {
+class LambdaDestructor final : public Destructor {
  public:
   explicit LambdaDestructor(F &&f) : f_(std::move(f)) {
   }
diff --git a/tdutils/td/utils/FileLog.h b/tdutils/td/utils/FileLog.h
index b57434f0c..c93239990 100644
--- a/tdutils/td/utils/FileLog.h
+++ b/tdutils/td/utils/FileLog.h
@@ -16,7 +16,7 @@
 
 namespace td {
 
-class FileLog : public LogInterface {
+class FileLog final : public LogInterface {
   static constexpr int64 DEFAULT_ROTATE_THRESHOLD = 10 * (1 << 20);
 
  public:
diff --git a/tdutils/td/utils/JsonBuilder.h b/tdutils/td/utils/JsonBuilder.h
index efd30c7f9..4c6d54c33 100644
--- a/tdutils/td/utils/JsonBuilder.h
+++ b/tdutils/td/utils/JsonBuilder.h
@@ -311,7 +311,7 @@ class JsonScope {
   }
 };
 
-class JsonValueScope : public JsonScope {
+class JsonValueScope final : public JsonScope {
  public:
   using JsonScope::JsonScope;
   template <class T>
@@ -336,7 +336,7 @@ class JsonValueScope : public JsonScope {
   bool was_ = false;
 };
 
-class JsonArrayScope : public JsonScope {
+class JsonArrayScope final : public JsonScope {
  public:
   explicit JsonArrayScope(JsonBuilder *jb) : JsonScope(jb) {
     jb->inc_offset();
@@ -377,7 +377,7 @@ class JsonArrayScope : public JsonScope {
   bool is_first_ = false;
 };
 
-class JsonObjectScope : public JsonScope {
+class JsonObjectScope final : public JsonScope {
  public:
   explicit JsonObjectScope(JsonBuilder *jb) : JsonScope(jb) {
     jb->inc_offset();
@@ -448,7 +448,7 @@ class JsonValue;
 using JsonObject = vector<std::pair<MutableSlice, JsonValue>>;
 using JsonArray = vector<JsonValue>;
 
-class JsonValue : public Jsonable {
+class JsonValue final : public Jsonable {
  public:
   enum class Type { Null, Number, Boolean, String, Array, Object };
 
@@ -696,7 +696,7 @@ class VirtuallyJsonable : public Jsonable {
   virtual ~VirtuallyJsonable() = default;
 };
 
-class VirtuallyJsonableInt : public VirtuallyJsonable {
+class VirtuallyJsonableInt final : public VirtuallyJsonable {
  public:
   explicit VirtuallyJsonableInt(int32 value) : value_(value) {
   }
@@ -708,7 +708,7 @@ class VirtuallyJsonableInt : public VirtuallyJsonable {
   int32 value_;
 };
 
-class VirtuallyJsonableLong : public VirtuallyJsonable {
+class VirtuallyJsonableLong final : public VirtuallyJsonable {
  public:
   explicit VirtuallyJsonableLong(int64 value) : value_(value) {
   }
@@ -720,7 +720,7 @@ class VirtuallyJsonableLong : public VirtuallyJsonable {
   int64 value_;
 };
 
-class VirtuallyJsonableString : public VirtuallyJsonable {
+class VirtuallyJsonableString final : public VirtuallyJsonable {
  public:
   explicit VirtuallyJsonableString(Slice value) : value_(value) {
   }
@@ -766,7 +766,7 @@ StrT json_encode(const ValT &val, bool pretty = false) {
 }
 
 template <class T>
-class ToJsonImpl : public Jsonable {
+class ToJsonImpl final : public Jsonable {
  public:
   explicit ToJsonImpl(const T &value) : value_(value) {
   }
diff --git a/tdutils/td/utils/MemoryLog.h b/tdutils/td/utils/MemoryLog.h
index 06bc2508c..a634a0955 100644
--- a/tdutils/td/utils/MemoryLog.h
+++ b/tdutils/td/utils/MemoryLog.h
@@ -17,7 +17,7 @@
 namespace td {
 
 template <int buffer_size = 32 * (1 << 10)>
-class MemoryLog : public LogInterface {
+class MemoryLog final : public LogInterface {
   static constexpr size_t MAX_OUTPUT_SIZE = buffer_size / 16 < (8 << 10) ? buffer_size / 16 : (8 << 10);
 
   static_assert((buffer_size & (buffer_size - 1)) == 0, "Buffer size must be power of 2");
diff --git a/tdutils/td/utils/NullLog.h b/tdutils/td/utils/NullLog.h
index 0752eceea..9f44a6f43 100644
--- a/tdutils/td/utils/NullLog.h
+++ b/tdutils/td/utils/NullLog.h
@@ -11,7 +11,7 @@
 
 namespace td {
 
-class NullLog : public LogInterface {
+class NullLog final : public LogInterface {
   void do_append(int /*log_level*/, CSlice /*slice*/) final {
   }
 };
diff --git a/tdutils/td/utils/Observer.h b/tdutils/td/utils/Observer.h
index 9366d9a80..46524900a 100644
--- a/tdutils/td/utils/Observer.h
+++ b/tdutils/td/utils/Observer.h
@@ -22,7 +22,7 @@ class ObserverBase {
   virtual void notify() = 0;
 };
 
-class Observer : ObserverBase {
+class Observer final : private ObserverBase {
  public:
   Observer() = default;
   explicit Observer(unique_ptr<ObserverBase> &&ptr) : observer_ptr_(std::move(ptr)) {
diff --git a/tdutils/td/utils/ScopeGuard.h b/tdutils/td/utils/ScopeGuard.h
index 3e67c2713..59b808940 100644
--- a/tdutils/td/utils/ScopeGuard.h
+++ b/tdutils/td/utils/ScopeGuard.h
@@ -29,7 +29,7 @@ class Guard {
 };
 
 template <class FunctionT>
-class LambdaGuard : public Guard {
+class LambdaGuard final : public Guard {
  public:
   explicit LambdaGuard(const FunctionT &func) : func_(func) {
   }
diff --git a/tdutils/td/utils/Storer.h b/tdutils/td/utils/Storer.h
index 47c53d15b..281bdece7 100644
--- a/tdutils/td/utils/Storer.h
+++ b/tdutils/td/utils/Storer.h
@@ -17,7 +17,7 @@
 
 namespace td {
 
-class SliceStorer : public Storer {
+class SliceStorer final : public Storer {
   Slice slice;
 
  public:
@@ -36,7 +36,7 @@ inline SliceStorer create_storer(Slice slice) {
   return SliceStorer(slice);
 }
 
-class ConcatStorer : public Storer {
+class ConcatStorer final : public Storer {
   const Storer &a_;
   const Storer &b_;
 
@@ -61,7 +61,7 @@ inline ConcatStorer create_storer(const Storer &a, const Storer &b) {
 }
 
 template <class T>
-class DefaultStorer : public Storer {
+class DefaultStorer final : public Storer {
  public:
   explicit DefaultStorer(const T &object) : object_(object) {
   }
diff --git a/tdutils/td/utils/TsFileLog.cpp b/tdutils/td/utils/TsFileLog.cpp
index e904b5dd7..51ca4d54e 100644
--- a/tdutils/td/utils/TsFileLog.cpp
+++ b/tdutils/td/utils/TsFileLog.cpp
@@ -21,7 +21,7 @@
 namespace td {
 
 namespace detail {
-class TsFileLog : public LogInterface {
+class TsFileLog final : public LogInterface {
  public:
   Status init(string path, int64 rotate_threshold, bool redirect_stderr) {
     path_ = std::move(path);
diff --git a/tdutils/td/utils/TsList.h b/tdutils/td/utils/TsList.h
index c5a24b026..0f4b8943a 100644
--- a/tdutils/td/utils/TsList.h
+++ b/tdutils/td/utils/TsList.h
@@ -159,7 +159,7 @@ class TsListNode : protected ListNode {
 };
 
 template <class DataT>
-class TsList : public TsListNode<DataT> {
+class TsList final : public TsListNode<DataT> {
  public:
   TsList() {
     this->parent = this;
diff --git a/tdutils/td/utils/TsLog.h b/tdutils/td/utils/TsLog.h
index 4dfb3e44d..59e40b3a1 100644
--- a/tdutils/td/utils/TsLog.h
+++ b/tdutils/td/utils/TsLog.h
@@ -14,7 +14,7 @@
 
 namespace td {
 
-class TsLog : public LogInterface {
+class TsLog final : public LogInterface {
  public:
   explicit TsLog(LogInterface *log) : log_(log) {
   }
diff --git a/tdutils/td/utils/Variant.h b/tdutils/td/utils/Variant.h
index 575c08dba..b964d488a 100644
--- a/tdutils/td/utils/Variant.h
+++ b/tdutils/td/utils/Variant.h
@@ -55,7 +55,7 @@ class IthTypeImpl<pos, Skip, Args...> : public IthTypeImpl<pos - 1, Args...> {};
 class Dummy {};
 
 template <size_t pos, class... Args>
-class IthType : public IthTypeImpl<pos, Args..., Dummy> {};
+class IthType final : public IthTypeImpl<pos, Args..., Dummy> {};
 
 template <bool ok, int offset, class... Types>
 class FindTypeOffsetImpl {};
@@ -69,7 +69,7 @@ template <int offset, class T, class S, class... Types>
 class FindTypeOffsetImpl<false, offset, T, S, Types...>
     : public FindTypeOffsetImpl<std::is_same<T, S>::value, offset + 1, T, Types...> {};
 template <class T, class... Types>
-class FindTypeOffset : public FindTypeOffsetImpl<false, -1, T, Types...> {};
+class FindTypeOffset final : public FindTypeOffsetImpl<false, -1, T, Types...> {};
 
 template <int offset, class... Types>
 class ForEachTypeImpl {};
diff --git a/tdutils/td/utils/benchmark.h b/tdutils/td/utils/benchmark.h
index 1daf0ab48..aa898ce88 100644
--- a/tdutils/td/utils/benchmark.h
+++ b/tdutils/td/utils/benchmark.h
@@ -15,14 +15,14 @@
 #include <tuple>
 #include <utility>
 
-#define BENCH(name, desc)                       \
-  class name##Bench : public ::td::Benchmark {  \
-   public:                                      \
-    std::string get_description() const final { \
-      return (desc);                            \
-    }                                           \
-    void run(int n) final;                      \
-  };                                            \
+#define BENCH(name, desc)                            \
+  class name##Bench final : public ::td::Benchmark { \
+   public:                                           \
+    std::string get_description() const final {      \
+      return (desc);                                 \
+    }                                                \
+    void run(int n) final;                           \
+  };                                                 \
   void name##Bench::run(int n)
 
 namespace td {
diff --git a/tdutils/td/utils/invoke.h b/tdutils/td/utils/invoke.h
index 185ace36d..f26a24378 100644
--- a/tdutils/td/utils/invoke.h
+++ b/tdutils/td/utils/invoke.h
@@ -203,8 +203,8 @@ auto call_n_arguments(F &&f, Args &&... args) {
 }
 
 template <class F, class X, class = void>
-struct is_callable : public std::false_type {};
+struct is_callable final : public std::false_type {};
 template <class F, class X>
-struct is_callable<F, X, decltype(std::declval<F>()(std::declval<X>()))> : public std::true_type {};
+struct is_callable<F, X, decltype(std::declval<F>()(std::declval<X>()))> final : public std::true_type {};
 
 }  // namespace td
diff --git a/tdutils/td/utils/logging.cpp b/tdutils/td/utils/logging.cpp
index 692b6cfb9..956aab579 100644
--- a/tdutils/td/utils/logging.cpp
+++ b/tdutils/td/utils/logging.cpp
@@ -150,7 +150,7 @@ Logger::~Logger() {
   }
 }
 
-class DefaultLog : public LogInterface {
+class DefaultLog final : public LogInterface {
   void do_append(int log_level, CSlice slice) final {
 #if TD_ANDROID
     switch (log_level) {
diff --git a/tdutils/td/utils/misc.h b/tdutils/td/utils/misc.h
index 731ea0c69..ac5ea64b4 100644
--- a/tdutils/td/utils/misc.h
+++ b/tdutils/td/utils/misc.h
@@ -271,7 +271,7 @@ MutableSlice url_decode_inplace(MutableSlice str, bool decode_plus_sign_as_space
 
 namespace detail {
 template <class T, class U>
-struct is_same_signedness
+struct is_same_signedness final
     : public std::integral_constant<bool, std::is_signed<T>::value == std::is_signed<U>::value> {};
 
 template <class T, class Enable = void>
diff --git a/tdutils/td/utils/overloaded.h b/tdutils/td/utils/overloaded.h
index 011cd51c6..ca3511e77 100644
--- a/tdutils/td/utils/overloaded.h
+++ b/tdutils/td/utils/overloaded.h
@@ -22,7 +22,7 @@ struct overload<F> : public F {
 template <class F, class... Fs>
 struct overload<F, Fs...>
     : public overload<F>
-    , overload<Fs...> {
+    , public overload<Fs...> {
   overload(F f, Fs... fs) : overload<F>(f), overload<Fs...>(fs...) {
   }
   using overload<F>::operator();
diff --git a/tdutils/td/utils/port/ServerSocketFd.cpp b/tdutils/td/utils/port/ServerSocketFd.cpp
index ff908a8e9..d15874ec7 100644
--- a/tdutils/td/utils/port/ServerSocketFd.cpp
+++ b/tdutils/td/utils/port/ServerSocketFd.cpp
@@ -40,7 +40,7 @@ namespace td {
 
 namespace detail {
 #if TD_PORT_WINDOWS
-class ServerSocketFdImpl : private Iocp::Callback {
+class ServerSocketFdImpl final : private Iocp::Callback {
  public:
   ServerSocketFdImpl(NativeFd fd, int socket_family) : info_(std::move(fd)), socket_family_(socket_family) {
     VLOG(fd) << get_native_fd() << " create ServerSocketFd";
diff --git a/tdutils/td/utils/port/SocketFd.cpp b/tdutils/td/utils/port/SocketFd.cpp
index ed00c1f4f..15e448a19 100644
--- a/tdutils/td/utils/port/SocketFd.cpp
+++ b/tdutils/td/utils/port/SocketFd.cpp
@@ -41,7 +41,7 @@
 namespace td {
 namespace detail {
 #if TD_PORT_WINDOWS
-class SocketFdImpl : private Iocp::Callback {
+class SocketFdImpl final : private Iocp::Callback {
  public:
   explicit SocketFdImpl(NativeFd native_fd) : info(std::move(native_fd)) {
     VLOG(fd) << get_native_fd() << " create from native_fd";
diff --git a/tdutils/td/utils/port/StdStreams.cpp b/tdutils/td/utils/port/StdStreams.cpp
index 09396fffa..a311e04df 100644
--- a/tdutils/td/utils/port/StdStreams.cpp
+++ b/tdutils/td/utils/port/StdStreams.cpp
@@ -69,7 +69,7 @@ FileFd &Stderr() {
 
 #if TD_PORT_WINDOWS
 namespace detail {
-class BufferedStdinImpl : public Iocp::Callback {
+class BufferedStdinImpl final : private Iocp::Callback {
  public:
 #if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP | WINAPI_PARTITION_SYSTEM)
   BufferedStdinImpl() : info_(NativeFd(GetStdHandle(STD_INPUT_HANDLE), true)) {
diff --git a/tdutils/td/utils/port/UdpSocketFd.cpp b/tdutils/td/utils/port/UdpSocketFd.cpp
index aac3d504c..a8da87664 100644
--- a/tdutils/td/utils/port/UdpSocketFd.cpp
+++ b/tdutils/td/utils/port/UdpSocketFd.cpp
@@ -98,7 +98,7 @@ class UdpSocketSendHelper {
   WSABUF buf_;
 };
 
-class UdpSocketFdImpl : private Iocp::Callback {
+class UdpSocketFdImpl final : private Iocp::Callback {
  public:
   explicit UdpSocketFdImpl(NativeFd fd) : info_(std::move(fd)) {
     get_poll_info().add_flags(PollFlags::Write());
diff --git a/tdutils/td/utils/port/detail/PollableFd.h b/tdutils/td/utils/port/detail/PollableFd.h
index 69410c891..dd4e86a1a 100644
--- a/tdutils/td/utils/port/detail/PollableFd.h
+++ b/tdutils/td/utils/port/detail/PollableFd.h
@@ -60,7 +60,7 @@ inline PollableFd PollableFdRef::lock() {
   return PollableFd::from_list_node(list_node_);
 }
 
-class PollableFdInfo : private ListNode {
+class PollableFdInfo final : private ListNode {
  public:
   PollableFdInfo() = default;
   PollableFdInfo(const PollableFdInfo &) = delete;
diff --git a/tdutils/td/utils/queue.h b/tdutils/td/utils/queue.h
index cd0b6ca2c..15f200591 100644
--- a/tdutils/td/utils/queue.h
+++ b/tdutils/td/utils/queue.h
@@ -285,7 +285,7 @@ class SPSCChainQueue {
 };
 
 template <class T, class QueueT = SPSCChainQueue<T>, class BackoffT = detail::Backoff>
-class BackoffQueue : public QueueT {
+class BackoffQueue final : public QueueT {
  public:
   using ValueType = T;
 
@@ -312,7 +312,7 @@ template <class T, class QueueT = SPSCChainQueue<T> >
 using InfBackoffQueue = BackoffQueue<T, QueueT, detail::InfBackoff>;
 
 template <class T, class QueueT = BackoffQueue<T> >
-class PollQueue : public QueueT {
+class PollQueue final : public QueueT {
  public:
   using ValueType = T;
   using QueueType = QueueT;
diff --git a/tdutils/td/utils/tests.cpp b/tdutils/td/utils/tests.cpp
index 380e6d464..ecb14a968 100644
--- a/tdutils/td/utils/tests.cpp
+++ b/tdutils/td/utils/tests.cpp
@@ -58,7 +58,7 @@ StringBuilder &operator<<(StringBuilder &sb, const TestInfo &info) {
   return sb << info.name << " " << info.result_hash << "\n";
 }
 
-class RegressionTesterImpl : public RegressionTester {
+class RegressionTesterImpl final : public RegressionTester {
  public:
   static void destroy(CSlice db_path) {
     unlink(db_path).ignore();
diff --git a/tdutils/td/utils/tests.h b/tdutils/td/utils/tests.h
index 00137d4b6..ec8377db5 100644
--- a/tdutils/td/utils/tests.h
+++ b/tdutils/td/utils/tests.h
@@ -85,7 +85,7 @@ class TestContext : public Context<TestContext> {
   virtual Status verify(Slice data) = 0;
 };
 
-class TestsRunner : public TestContext {
+class TestsRunner final : public TestContext {
  public:
   static TestsRunner &get_default();
 
@@ -170,7 +170,7 @@ void assert_true_impl(const T &got, const char *file, int line) {
 #define TEST(test_case_name, test_name) TEST_IMPL(TEST_NAME(test_case_name, test_name))
 
 #define TEST_IMPL(test_name)                                                                                         \
-  class test_name : public ::td::Test {                                                                              \
+  class test_name final : public ::td::Test {                                                                        \
    public:                                                                                                           \
     using Test::Test;                                                                                                \
     void run() final;                                                                                                \
diff --git a/tdutils/test/ConcurrentHashMap.cpp b/tdutils/test/ConcurrentHashMap.cpp
index aa9351d53..c9c9b42b1 100644
--- a/tdutils/test/ConcurrentHashMap.cpp
+++ b/tdutils/test/ConcurrentHashMap.cpp
@@ -177,7 +177,7 @@ class ConcurrentHashMapJunction {
 }  // namespace td
 
 template <class HashMap>
-class HashMapBenchmark : public td::Benchmark {
+class HashMapBenchmark final : public td::Benchmark {
   struct Query {
     int key;
     int value;
diff --git a/tdutils/test/List.cpp b/tdutils/test/List.cpp
index d3cf39f61..0d29b0e6c 100644
--- a/tdutils/test/List.cpp
+++ b/tdutils/test/List.cpp
@@ -26,7 +26,7 @@ struct ListData {
   }
 };
 
-struct Node : public td::ListNode {
+struct Node final : public td::ListNode {
   Node() = default;
   explicit Node(ListData data) : data(std::move(data)) {
   }
diff --git a/tdutils/test/MpscLinkQueue.cpp b/tdutils/test/MpscLinkQueue.cpp
index 9570151f8..9c0e3886c 100644
--- a/tdutils/test/MpscLinkQueue.cpp
+++ b/tdutils/test/MpscLinkQueue.cpp
@@ -11,7 +11,7 @@
 #include "td/utils/port/thread.h"
 #include "td/utils/tests.h"
 
-class NodeX : public td::MpscLinkQueueImpl::Node {
+class NodeX final : public td::MpscLinkQueueImpl::Node {
  public:
   explicit NodeX(int value) : value_(value) {
   }
diff --git a/tdutils/test/crypto.cpp b/tdutils/test/crypto.cpp
index cab285f4f..c7abbd61d 100644
--- a/tdutils/test/crypto.cpp
+++ b/tdutils/test/crypto.cpp
@@ -362,7 +362,7 @@ TEST(Crypto, crc32c) {
 }
 
 TEST(Crypto, crc32c_benchmark) {
-  class Crc32cExtendBenchmark : public td::Benchmark {
+  class Crc32cExtendBenchmark final : public td::Benchmark {
    public:
     explicit Crc32cExtendBenchmark(size_t chunk_size) : chunk_size_(chunk_size) {
     }
diff --git a/tdutils/test/heap.cpp b/tdutils/test/heap.cpp
index 633e884ae..6c2c9ad3c 100644
--- a/tdutils/test/heap.cpp
+++ b/tdutils/test/heap.cpp
@@ -135,7 +135,7 @@ class CheckedHeap {
   }
 
  private:
-  struct Node : public td::HeapNode {
+  struct Node final : public td::HeapNode {
     Node() = default;
     Node(int key, int value) : key(key), value(value) {
     }
diff --git a/tdutils/test/log.cpp b/tdutils/test/log.cpp
index 349f63db7..571235d43 100644
--- a/tdutils/test/log.cpp
+++ b/tdutils/test/log.cpp
@@ -26,7 +26,7 @@ char disable_linker_warning_about_empty_file_tdutils_test_log_cpp TD_UNUSED;
 
 #if !TD_THREAD_UNSUPPORTED
 template <class Log>
-class LogBenchmark : public td::Benchmark {
+class LogBenchmark final : public td::Benchmark {
  public:
   LogBenchmark(std::string name, int threads_n, bool test_full_logging, std::function<td::unique_ptr<Log>()> creator)
       : name_(std::move(name))
@@ -116,7 +116,7 @@ TEST(Log, Bench) {
             [] { return td::TsFileLog::create("tmplog", std::numeric_limits<td::int64>::max(), false).move_as_ok(); });
 
   bench_log("FileLog + TsLog", [] {
-    class FileLog : public td::LogInterface {
+    class FileLog final : public td::LogInterface {
      public:
       FileLog() {
         file_log_.init("tmplog", std::numeric_limits<td::int64>::max(), false).ensure();
@@ -137,7 +137,7 @@ TEST(Log, Bench) {
   });
 
   bench_log("FileLog", [] {
-    class FileLog : public td::LogInterface {
+    class FileLog final : public td::LogInterface {
      public:
       FileLog() {
         file_log_.init("tmplog", std::numeric_limits<td::int64>::max(), false).ensure();
diff --git a/test/db.cpp b/test/db.cpp
index 063c8c7b7..2badeeda4 100644
--- a/test/db.cpp
+++ b/test/db.cpp
@@ -554,7 +554,7 @@ TEST(DB, persistent_key_value) {
     }
 
     std::vector<std::vector<DbQuery>> res(threads_n);
-    class Worker : public Actor {
+    class Worker final : public Actor {
      public:
       Worker(ActorShared<> parent, std::shared_ptr<QueryHandler<KeyValue>> kv, const std::vector<DbQuery> *queries,
              std::vector<DbQuery> *res)
@@ -574,7 +574,7 @@ TEST(DB, persistent_key_value) {
       const std::vector<DbQuery> *queries_;
       std::vector<DbQuery> *res_;
     };
-    class Main : public Actor {
+    class Main final : public Actor {
      public:
       Main(int threads_n, const std::vector<std::vector<DbQuery>> *queries, std::vector<std::vector<DbQuery>> *res)
           : threads_n_(threads_n), queries_(queries), res_(res), ref_cnt_(threads_n) {
diff --git a/test/mtproto.cpp b/test/mtproto.cpp
index 5c10e760e..1e6e5e6b9 100644
--- a/test/mtproto.cpp
+++ b/test/mtproto.cpp
@@ -196,7 +196,7 @@ TEST(Mtproto, encrypted_config) {
   auto config = decode_config(data).move_as_ok();
 }
 
-class TestPingActor : public Actor {
+class TestPingActor final : public Actor {
  public:
   TestPingActor(IPAddress ip_address, Status *result) : ip_address_(ip_address), result_(result) {
   }
@@ -264,7 +264,7 @@ static int32 get_default_dc_id() {
   return 10002;
 }
 
-class Mtproto_ping : public Test {
+class Mtproto_ping final : public Test {
  public:
   using Test::Test;
   bool step() final {
@@ -293,7 +293,7 @@ class Mtproto_ping : public Test {
 };
 RegisterTest<Mtproto_ping> mtproto_ping("Mtproto_ping");
 
-class HandshakeContext : public mtproto::AuthKeyHandshakeContext {
+class HandshakeContext final : public mtproto::AuthKeyHandshakeContext {
  public:
   DhCallback *get_dh_callback() final {
     return nullptr;
@@ -306,7 +306,7 @@ class HandshakeContext : public mtproto::AuthKeyHandshakeContext {
   PublicRsaKeyShared public_rsa_key{DcId::empty(), false};
 };
 
-class HandshakeTestActor : public Actor {
+class HandshakeTestActor final : public Actor {
  public:
   HandshakeTestActor(int32 dc_id, Status *result) : dc_id_(dc_id), result_(result) {
   }
@@ -404,7 +404,7 @@ class HandshakeTestActor : public Actor {
   }
 };
 
-class Mtproto_handshake : public Test {
+class Mtproto_handshake final : public Test {
  public:
   using Test::Test;
   bool step() final {
@@ -433,14 +433,14 @@ class Mtproto_handshake : public Test {
 };
 RegisterTest<Mtproto_handshake> mtproto_handshake("Mtproto_handshake");
 
-class Socks5TestActor : public Actor {
+class Socks5TestActor final : public Actor {
  public:
   void start_up() final {
     auto promise = PromiseCreator::lambda([actor_id = actor_id(this)](Result<SocketFd> res) {
       send_closure(actor_id, &Socks5TestActor::on_result, std::move(res), false);
     });
 
-    class Callback : public TransparentProxy::Callback {
+    class Callback final : public TransparentProxy::Callback {
      public:
       explicit Callback(Promise<SocketFd> promise) : promise_(std::move(promise)) {
       }
@@ -521,7 +521,7 @@ TEST(Mtproto, notifications) {
   }
 }
 
-class FastPingTestActor : public Actor {
+class FastPingTestActor final : public Actor {
  public:
   explicit FastPingTestActor(Status *result) : result_(result) {
   }
@@ -623,7 +623,7 @@ class FastPingTestActor : public Actor {
   }
 };
 
-class Mtproto_FastPing : public Test {
+class Mtproto_FastPing final : public Test {
  public:
   using Test::Test;
   bool step() final {
@@ -670,9 +670,9 @@ TEST(Mtproto, TlsTransport) {
   sched.init(threads_n);
   {
     auto guard = sched.get_main_guard();
-    class RunTest : public Actor {
+    class RunTest final : public Actor {
       void start_up() final {
-        class Callback : public TransparentProxy::Callback {
+        class Callback final : public TransparentProxy::Callback {
          public:
           void set_result(Result<SocketFd> result) final {
             if (result.is_ok()) {
diff --git a/test/secret.cpp b/test/secret.cpp
index 24f07ed2c..a223935d2 100644
--- a/test/secret.cpp
+++ b/test/secret.cpp
@@ -334,7 +334,7 @@ static string prime_base64 =
     "WC2xF40WnGvEZbDW_5yjko_vW5rk5Bj8Feg-vqD4f6n_Xu1wBQ3tKEn0e_lZ2VaFDOkphR8NgRX2NbEF7i5OFdBLJFS_b0-t8DSxBAMRnNjjuS_MW"
     "w";
 
-class FakeDhCallback : public DhCallback {
+class FakeDhCallback final : public DhCallback {
  public:
   int is_good_prime(Slice prime_str) const final {
     auto it = cache.find(prime_str.str());
@@ -352,7 +352,7 @@ class FakeDhCallback : public DhCallback {
   mutable std::map<string, int> cache;
 };
 
-class FakeBinlog
+class FakeBinlog final
     : public BinlogInterface
     , public Actor {
  public:
@@ -479,7 +479,7 @@ class FakeBinlog
 using FakeKeyValue = BinlogKeyValue<BinlogInterface>;
 
 class Master;
-class FakeSecretChatContext : public SecretChatActor::Context {
+class FakeSecretChatContext final : public SecretChatActor::Context {
  public:
   FakeSecretChatContext(std::shared_ptr<BinlogInterface> binlog, std::shared_ptr<KeyValueSyncInterface> key_value,
                         std::shared_ptr<bool> close_flag, ActorShared<Master> master)
@@ -565,11 +565,11 @@ class FakeSecretChatContext : public SecretChatActor::Context {
 };
 NetQueryCreator FakeSecretChatContext::net_query_creator_;
 
-class Master : public Actor {
+class Master final : public Actor {
  public:
   explicit Master(Status *status) : status_(status) {
   }
-  class SecretChatProxy : public Actor {
+  class SecretChatProxy final : public Actor {
    public:
     SecretChatProxy(string name, ActorShared<Master> parent) : name_(std::move(name)) {
       binlog_ = std::make_shared<FakeBinlog>();
diff --git a/test/tdclient.cpp b/test/tdclient.cpp
index dffe30c8c..eaba531d7 100644
--- a/test/tdclient.cpp
+++ b/test/tdclient.cpp
@@ -46,7 +46,7 @@ static void check_td_error(T &result) {
   LOG_CHECK(result->get_id() != td::td_api::error::ID) << to_string(result);
 }
 
-class TestClient : public td::Actor {
+class TestClient final : public td::Actor {
  public:
   explicit TestClient(td::string name) : name_(std::move(name)) {
   }
@@ -76,7 +76,7 @@ class TestClient : public td::Actor {
   }
 
   td::unique_ptr<td::TdCallback> make_td_callback() {
-    class TdCallbackImpl : public td::TdCallback {
+    class TdCallbackImpl final : public td::TdCallback {
      public:
       explicit TdCallbackImpl(td::ActorId<TestClient> client) : client_(client) {
       }
@@ -197,7 +197,7 @@ class TestClinetTask : public TestClient::Listener {
   }
 };
 
-class DoAuthentication : public TestClinetTask {
+class DoAuthentication final : public TestClinetTask {
  public:
   DoAuthentication(td::string name, td::string phone, td::string code, td::Promise<> promise)
       : name_(std::move(name)), phone_(std::move(phone)), code_(std::move(code)), promise_(std::move(promise)) {
@@ -273,7 +273,7 @@ class DoAuthentication : public TestClinetTask {
   }
 };
 
-class SetUsername : public TestClinetTask {
+class SetUsername final : public TestClinetTask {
  public:
   SetUsername(td::string username, td::Promise<> promise)
       : username_(std::move(username)), promise_(std::move(promise)) {
@@ -338,7 +338,7 @@ class SetUsername : public TestClinetTask {
   }
 };
 
-class CheckTestA : public TestClinetTask {
+class CheckTestA final : public TestClinetTask {
  public:
   CheckTestA(td::string tag, td::Promise<> promise) : tag_(std::move(tag)), promise_(std::move(promise)) {
   }
@@ -370,7 +370,7 @@ class CheckTestA : public TestClinetTask {
   }
 };
 
-class TestA : public TestClinetTask {
+class TestA final : public TestClinetTask {
  public:
   TestA(td::string tag, td::string username) : tag_(std::move(tag)), username_(std::move(username)) {
   }
@@ -396,7 +396,7 @@ class TestA : public TestClinetTask {
   td::string username_;
 };
 
-class TestSecretChat : public TestClinetTask {
+class TestSecretChat final : public TestClinetTask {
  public:
   TestSecretChat(td::string tag, td::string username) : tag_(std::move(tag)), username_(std::move(username)) {
   }
@@ -447,7 +447,7 @@ class TestSecretChat : public TestClinetTask {
   td::int64 chat_id_ = 0;
 };
 
-class TestFileGenerated : public TestClinetTask {
+class TestFileGenerated final : public TestClinetTask {
  public:
   TestFileGenerated(td::string tag, td::string username) : tag_(std::move(tag)), username_(std::move(username)) {
   }
@@ -511,7 +511,7 @@ class TestFileGenerated : public TestClinetTask {
                [](auto res) { check_td_error(res); });
   }
 
-  class GenerateFile : public td::Actor {
+  class GenerateFile final : public td::Actor {
    public:
     GenerateFile(TestClinetTask *parent, td::int64 id, td::string original_path, td::string destination_path,
                  td::string conversion)
@@ -588,7 +588,7 @@ class TestFileGenerated : public TestClinetTask {
   td::int64 chat_id_ = 0;
 };
 
-class CheckTestC : public TestClinetTask {
+class CheckTestC final : public TestClinetTask {
  public:
   CheckTestC(td::string username, td::string tag, td::Promise<> promise)
       : username_(std::move(username)), tag_(std::move(tag)), promise_(std::move(promise)) {
@@ -658,7 +658,7 @@ class CheckTestC : public TestClinetTask {
   td::int32 file_id_to_check_ = 0;
 };
 
-class LoginTestActor : public td::Actor {
+class LoginTestActor final : public td::Actor {
  public:
   explicit LoginTestActor(td::Status *status) : status_(status) {
     *status_ = td::Status::OK();
@@ -705,7 +705,7 @@ class LoginTestActor : public td::Actor {
       init();
     } else if (start_up_fence_ == 1) {
       return init();
-      class WaitActor : public td::Actor {
+      class WaitActor final : public td::Actor {
        public:
         WaitActor(double timeout, td::Promise<> promise) : timeout_(timeout), promise_(std::move(promise)) {
         }
@@ -822,7 +822,7 @@ class LoginTestActor : public td::Actor {
   }
 };
 
-class Tdclient_login : public td::Test {
+class Tdclient_login final : public td::Test {
  public:
   using Test::Test;
   bool step() final {