From d7cff5b067761cb2d050dfb7a3b0ea45e5952f99 Mon Sep 17 00:00:00 2001
From: Dominik Authaler <dominik.authaler@uni-ulm.de>
Date: Tue, 13 Feb 2024 12:36:30 +0000
Subject: [PATCH] deprecation warnings for second template parameter

Co-authored-by: Jonas Otto <jonas@jonasotto.com>
Signed-off-by: Dominik Authaler <dominik.authaler@uni-ulm.de>
---
 include/message_filters/subscriber.h | 45 ++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/include/message_filters/subscriber.h b/include/message_filters/subscriber.h
index 6cda5d0..ac4e633 100644
--- a/include/message_filters/subscriber.h
+++ b/include/message_filters/subscriber.h
@@ -62,11 +62,12 @@ class SubscriberBase
 
   using RequiredInterfaces = rclcpp::node_interfaces::NodeInterfaces<NodeParametersInterface, NodeTopicsInterface>;
 
-  SubscriberBase() {
-    if constexpr (not std::is_same_v<NodeType, DeprecatedTemplateParameter>) {
-        // TODO: deprecation warning, similar to static_assert but only throwing a warning
-    }
-  }
+  template<typename U = NodeType, std::enable_if_t<std::is_same<U, DeprecatedTemplateParameter>{}, int> = 0>
+  SubscriberBase() {}
+
+  template<typename U = NodeType, std::enable_if_t<!std::is_same<U, DeprecatedTemplateParameter>{}, int> = 0>
+  [[deprecated("Template parameter of SubscriberBase class has been deprecated and will be removed in future releases")]]
+  SubscriberBase() {}
 
   virtual ~SubscriberBase() = default;
 
@@ -175,6 +176,30 @@ class Subscriber
   using NodeParametersInterface = typename SubscriberBase<NodeType>::NodeParametersInterface;
   using NodeTopicsInterface = typename SubscriberBase<NodeType>::NodeTopicsInterface;
 
+  /**
+   * \brief Solely for highlighting deprecated template parameters with a compiler warning
+   */
+  template<typename U = NodeType, std::enable_if_t<!std::is_same<U, DeprecatedTemplateParameter>{}, int> = 0>
+  [[deprecated("Second template parameter of Subscriber class is deprecated and will be removed in a future release")]]
+  Subscriber(RequiredInterfaces node_interfaces,
+             const std::string& topic,
+             const rmw_qos_profile_t qos,
+             rclcpp::SubscriptionOptions options)
+  {
+      subscribe(node_interfaces, topic, qos, options);
+  }
+
+  /**
+   * \brief Solely for highlighting deprecated template parameters with a compiler warning
+   */
+  template<typename U = NodeType, std::enable_if_t<!std::is_same<U, DeprecatedTemplateParameter>{}, int> = 0>
+  [[deprecated("Second template parameter of Subscriber class is deprecated and will be removed in a future release")]]
+  Subscriber(RequiredInterfaces node_interfaces, const std::string& topic,
+             const rmw_qos_profile_t qos = rmw_qos_profile_default)
+  {
+      subscribe(node_interfaces, topic, qos);
+  }
+
   /**
    * \brief Constructor for rclcpp::Node / rclcpp_lifecycle::LifecycleNode.
    *
@@ -182,13 +207,10 @@ class Subscriber
    * \param topic The topic to subscribe to.
    * \param qos (optional) The rmw qos profile to use to subscribe
    */
+  template<typename U = NodeType, std::enable_if_t<std::is_same<U, DeprecatedTemplateParameter>{}, int> = 0>
   Subscriber(RequiredInterfaces node_interfaces, const std::string& topic,
              const rmw_qos_profile_t qos = rmw_qos_profile_default)
   {
-    if constexpr (not std::is_same_v<NodeType, DeprecatedTemplateParameter>) {
-      // TODO: deprecation warning, similar to static_assert but only throwing a warning
-    }
-
     subscribe(node_interfaces, topic, qos);
   }
 
@@ -222,15 +244,12 @@ class Subscriber
    * \param qos The rmw qos profile to use to subscribe.
    * \param options The subscription options to use to subscribe.
    */
+  template<typename U = NodeType, std::enable_if_t<std::is_same<U, DeprecatedTemplateParameter>{}, int> = 0>
   Subscriber(RequiredInterfaces node_interfaces,
              const std::string& topic,
              const rmw_qos_profile_t qos,
              rclcpp::SubscriptionOptions options)
   {
-    if constexpr (not std::is_same_v<NodeType, DeprecatedTemplateParameter>) {
-      // TODO: deprecation warning, similar to static_assert but only throwing a warning
-    }
-
     subscribe(node_interfaces, topic, qos, options);
   }