From 67c81c737e0be83c0ea77700aa84a257998813a0 Mon Sep 17 00:00:00 2001
From: Stefano Avallone <stavallo@unina.it>
Date: Thu, 9 Mar 2023 13:03:17 +0100
Subject: [PATCH] core: Explicitly instantiate some Callback class and function
 templates

---
 src/core/model/object-base.cc | 4 ++++
 src/core/model/object-base.h  | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/src/core/model/object-base.cc b/src/core/model/object-base.cc
index 65cc54c1f..14d61f81e 100644
--- a/src/core/model/object-base.cc
+++ b/src/core/model/object-base.cc
@@ -35,6 +35,10 @@
 
 namespace ns3
 {
+// Explicit instantiation declaration
+template Callback<ObjectBase*> MakeCallback<ObjectBase*>(ObjectBase* (*)());
+template Callback<ObjectBase*>::Callback();
+template class CallbackImpl<ObjectBase*>;
 
 NS_LOG_COMPONENT_DEFINE("ObjectBase");
 
diff --git a/src/core/model/object-base.h b/src/core/model/object-base.h
index 66aa4be1c..c496531cb 100644
--- a/src/core/model/object-base.h
+++ b/src/core/model/object-base.h
@@ -335,6 +335,15 @@ class ObjectBase
                const AttributeValue& value);
 };
 
+// The following explicit template instantiation declarations prevent all the translation
+// units including this header file to implicitly instantiate the callbacks class and
+// function templates having ObjectBase as template type parameter that are required to be
+// instantiated more often (accorging to the ClangBuildAnalyzer tool).
+// These classes and functions are explicitly instantiated in object-base.cc
+extern template Callback<ObjectBase*> MakeCallback<ObjectBase*>(ObjectBase* (*)());
+extern template Callback<ObjectBase*>::Callback();
+extern template class CallbackImpl<ObjectBase*>;
+
 } // namespace ns3
 
 #endif /* OBJECT_BASE_H */