Deprecate the usage of -> instead of . for objects that are not pointers (#811)

* Deprecate operator-> for objects that are not pointers

* Fix the deprecation warning in podio

---------

Co-authored-by: jmcarcell <jmcarcell@users.noreply.github.com>

Author: jmcarcell

python/templates/Collection.h.jinja2

@@ -74,6 +74,7 @@ public:
   void print(std::ostream& os=std::cout, bool flush=true) const final;
 
   /// operator to allow pointer like calling of members a la LCIO
+  [[deprecated("Use of operator->() is deprecated. Use . instead.")]]
   {{ class.bare_type }}Collection* operator->() { return static_cast<{{ class.bare_type }}Collection*>(this); }
 
   /// Append a new object to the collection, and return this object.

tests/unittests/frame.cpp

@@ -398,10 +398,10 @@ TEST_CASE("Frame destructor ASanFail") {
       auto& hitClusters = hitClusterMap[name];
 
       for (int i = 0; i < 3; ++i) {
-        auto cluster = hitClusters.first->create();
+        auto cluster = hitClusters.first.create();
 
         for (int j = 0; j < 5; ++j) {
-          auto hit = hitClusters.second->create();
+          auto hit = hitClusters.second.create();
           cluster.addHits(hit);
         }
       }