Make G() safe.

GitOrigin-RevId: d417008f94ce6f8c587561af352d696ef55895b3

td/telegram/Client.cpp

@@ -122,6 +122,9 @@ class MultiTd : public Actor {
      public:
       explicit TdActorContext(std::string tag) : tag_(std::move(tag)) {
       }
+      int32 get_id() const override {
+        return 0x172ae58d;
+      }
       std::string tag_;
     };
     auto context = std::make_shared<TdActorContext>(to_string(td_id));

td/telegram/Global.h

@@ -68,6 +68,11 @@ class Global : public ActorContext {
   Global(Global &&other) = delete;
   Global &operator=(Global &&other) = delete;
 
+  static constexpr int32 ID = -572104940;
+  int32 get_id() const override {
+    return ID;
+  }
+
 #define td_db() get_td_db_impl(__FILE__, __LINE__)
   TdDb *get_td_db_impl(const char *file, int line) {
     LOG_CHECK(td_db_) << close_flag() << " " << file << " " << line;
@@ -410,8 +415,10 @@ class Global : public ActorContext {
 };
 
 inline Global *G() {
-  CHECK(Scheduler::context());
-  return static_cast<Global *>(Scheduler::context());
+  ActorContext *context = Scheduler::context();
+  CHECK(context);
+  CHECK(context->get_id() == Global::ID);
+  return static_cast<Global *>(context);
 }
 
 }  // namespace td

tdactor/td/actor/impl/ActorInfo-decl.h

@@ -32,6 +32,11 @@ class ActorContext {
   ActorContext(ActorContext &&) = delete;
   ActorContext &operator=(ActorContext &&) = delete;
   virtual ~ActorContext() = default;
+
+  virtual int32 get_id() const {
+    return 0;
+  }
+
   const char *tag_ = nullptr;
   std::weak_ptr<ActorContext> this_ptr_;
 };

tdactor/test/actors_main.cpp

@@ -468,6 +468,10 @@ TEST(Actors, do_after_stop) {
 
 class XContext : public ActorContext {
  public:
+  int32 get_id() const override {
+    return 123456789;
+  }
+
   void validate() {
     CHECK(x == 1234);
   }
@@ -476,6 +480,7 @@ class XContext : public ActorContext {
   }
   int x = 1234;
 };
+
 class WithContext : public Actor {
  public:
   void start_up() override {