Remove const refs to shared pointers

include/spdlog/details/registry-inl.h

@@ -267,7 +267,7 @@ SPDLOG_INLINE void registry::register_logger_(std::shared_ptr<logger> new_logger
 }
 
 SPDLOG_INLINE void registry::add_on_registration_callback(
-    const std::function<void(const std::shared_ptr<logger>&)>& callback) {
+    const std::function<void(std::shared_ptr<logger>)>& callback) {
     std::lock_guard<std::mutex> lock(logger_map_mutex_);
     on_registration_callbacks_.push_back(callback);
 }

include/spdlog/details/registry.h

@@ -92,7 +92,7 @@ public:
 
     void apply_logger_env_levels(std::shared_ptr<logger> new_logger);
 
-    void add_on_registration_callback(const std::function<void(const std::shared_ptr<logger>&)>& callback);
+    void add_on_registration_callback(const std::function<void(std::shared_ptr<logger>)>& callback);
 
     void drop_all_on_registration_callbacks();
 
@@ -116,7 +116,7 @@ private:
     std::shared_ptr<logger> default_logger_;
     bool automatic_registration_ = true;
     size_t backtrace_n_messages_ = 0;
-    std::vector<std::function<void(const std::shared_ptr<logger>&)>> on_registration_callbacks_;
+    std::vector<std::function<void(std::shared_ptr<logger>)>> on_registration_callbacks_;
 };
 
 }  // namespace details

tests/test_registry.cpp

@@ -113,7 +113,7 @@ TEST_CASE("disable automatic registration", "[registry]") {
 
 TEST_CASE("add_on_registration_callback", "[registry]") {
     std::vector<std::string> registered_logger_names;
-    auto on_registration_callback = [&](const std::shared_ptr<spdlog::logger>& logger)
+    auto on_registration_callback = [&](std::shared_ptr<spdlog::logger> logger)
     {
         registered_logger_names.push_back(logger->name());
     };