diff --git a/src/vt/messaging/active.cc b/src/vt/messaging/active.cc
index 20bbbfb84f..bd3bc68c60 100644
--- a/src/vt/messaging/active.cc
+++ b/src/vt/messaging/active.cc
@@ -1073,7 +1073,7 @@ HandlerType ActiveMessenger::collectiveRegisterHandler(
 }
 
 void ActiveMessenger::swapHandlerFn(
-  HandlerType const& han, ActiveClosureFnType fn, TagType const& tag
+  HandlerType const han, ActiveClosureFnType fn, TagType const& tag
 ) {
   vt_debug_print(
     active, node,
@@ -1088,7 +1088,7 @@ void ActiveMessenger::swapHandlerFn(
 }
 
 void ActiveMessenger::deliverPendingMsgsHandler(
-  HandlerType const& han, TagType const& tag
+  HandlerType const han, TagType const& tag
 ) {
   vt_debug_print(
     active, node,
@@ -1118,7 +1118,7 @@ void ActiveMessenger::deliverPendingMsgsHandler(
 }
 
 void ActiveMessenger::registerHandlerFn(
-  HandlerType const& han, ActiveClosureFnType fn, TagType const& tag
+  HandlerType const han, ActiveClosureFnType fn, TagType const& tag
 ) {
   vt_debug_print(
     active, node,
@@ -1133,7 +1133,7 @@ void ActiveMessenger::registerHandlerFn(
 }
 
 void ActiveMessenger::unregisterHandlerFn(
-  HandlerType const& han, TagType const& tag
+  HandlerType const han, TagType const& tag
 ) {
   vt_debug_print(
     active, node,
diff --git a/src/vt/messaging/active.h b/src/vt/messaging/active.h
index 6d09943925..6e645297ae 100644
--- a/src/vt/messaging/active.h
+++ b/src/vt/messaging/active.h
@@ -1185,7 +1185,7 @@ struct ActiveMessenger : runtime::component::PollableComponent<ActiveMessenger>
    * \param[in] tag the tag this handler will accept (\c vt::no_tag means any)
    */
   void swapHandlerFn(
-    HandlerType const& han, ActiveClosureFnType fn, TagType const& tag = no_tag
+    HandlerType const han, ActiveClosureFnType fn, TagType const& tag = no_tag
   );
 
   /**
@@ -1195,7 +1195,7 @@ struct ActiveMessenger : runtime::component::PollableComponent<ActiveMessenger>
    * \param[in] han the handler to de-register
    * \param[in] tag the tag this handler will accept (\c vt::no_tag means any)
    */
-  void unregisterHandlerFn(HandlerType const& han, TagType const& tag = no_tag);
+  void unregisterHandlerFn(HandlerType const han, TagType const& tag = no_tag);
 
   /**
    * \internal
@@ -1206,7 +1206,7 @@ struct ActiveMessenger : runtime::component::PollableComponent<ActiveMessenger>
    * \param[in] tag the tag this handler will accept (\c vt::no_tag means any)
    */
   void registerHandlerFn(
-    HandlerType const& han, ActiveClosureFnType fn, TagType const& tag = no_tag
+    HandlerType const han, ActiveClosureFnType fn, TagType const& tag = no_tag
   );
 
   /**
@@ -1338,7 +1338,7 @@ struct ActiveMessenger : runtime::component::PollableComponent<ActiveMessenger>
    * \param[in] tag the tag for that handler
    */
   void deliverPendingMsgsHandler(
-    HandlerType const& han, TagType const& tag = no_tag
+    HandlerType const han, TagType const& tag = no_tag
   );
 
   /**
diff --git a/src/vt/messaging/envelope/envelope_set.h b/src/vt/messaging/envelope/envelope_set.h
index e9c76ceeb2..46db0872ec 100644
--- a/src/vt/messaging/envelope/envelope_set.h
+++ b/src/vt/messaging/envelope/envelope_set.h
@@ -124,7 +124,7 @@ inline void setTagType(Env& env);
  * \param[in] handler the handler
  */
 template <typename Env>
-inline void envelopeSetHandler(Env& env, HandlerType const& handler);
+inline void envelopeSetHandler(Env& env, HandlerType const handler);
 
 /**
  * \brief Set destination \c dest field in envelope
diff --git a/src/vt/messaging/envelope/envelope_set.impl.h b/src/vt/messaging/envelope/envelope_set.impl.h
index 16620ee957..4931660ccd 100644
--- a/src/vt/messaging/envelope/envelope_set.impl.h
+++ b/src/vt/messaging/envelope/envelope_set.impl.h
@@ -94,7 +94,7 @@ inline void setTagType(Env& env) {
 }
 
 template <typename Env>
-inline void envelopeSetHandler(Env& env, HandlerType const& handler) {
+inline void envelopeSetHandler(Env& env, HandlerType const handler) {
   vtAssert(not envelopeIsLocked(env), "Envelope locked.");
   reinterpret_cast<Envelope*>(&env)->han = handler;
 }
diff --git a/src/vt/messaging/envelope/envelope_setup.h b/src/vt/messaging/envelope/envelope_setup.h
index d0ed5f3e89..b9d05ac252 100644
--- a/src/vt/messaging/envelope/envelope_setup.h
+++ b/src/vt/messaging/envelope/envelope_setup.h
@@ -62,7 +62,7 @@ namespace vt {
  */
 template <typename Env>
 inline void envelopeSetup(
-  Env& env, NodeType const& dest, HandlerType const& handler
+  Env& env, NodeType const& dest, HandlerType const handler
 );
 
 /**
diff --git a/src/vt/messaging/envelope/envelope_setup.impl.h b/src/vt/messaging/envelope/envelope_setup.impl.h
index e5e7dbfc21..1ed6346017 100644
--- a/src/vt/messaging/envelope/envelope_setup.impl.h
+++ b/src/vt/messaging/envelope/envelope_setup.impl.h
@@ -53,7 +53,7 @@ namespace vt {
 
 template <typename Env>
 inline void envelopeSetup(
-  Env& env, NodeType const& dest, HandlerType const& handler
+  Env& env, NodeType const& dest, HandlerType const handler
 ) {
   envelopeSetDest(env, dest);
   envelopeSetHandler(env, handler);
diff --git a/src/vt/parameterization/parameterization.h b/src/vt/parameterization/parameterization.h
index d03b60e5ca..f79e4314be 100644
--- a/src/vt/parameterization/parameterization.h
+++ b/src/vt/parameterization/parameterization.h
@@ -73,12 +73,12 @@ struct DataMsg : vt::Message {
   HandlerType sub_han = uninitialized_handler;
 
   DataMsg() = default;
-  DataMsg(HandlerType const& in_sub_han, Tuple&& a)
+  DataMsg(HandlerType const in_sub_han, Tuple&& a)
     : Message(), tup(std::forward<Tuple>(a)), sub_han(in_sub_han)
   { }
 
   template <typename... Args>
-  DataMsg(HandlerType const& in_sub_han, Args&&... a)
+  DataMsg(HandlerType const in_sub_han, Args&&... a)
     : Message(), tup(std::forward<Args>(a)...), sub_han(in_sub_han)
   { }
 
@@ -144,7 +144,7 @@ struct Param : runtime::component::Component<Param> {
 
   template <typename... Args>
   void sendDataTuple(
-    NodeType const& dest, HandlerType const& han, std::tuple<Args...>&& tup
+    NodeType const& dest, HandlerType const han, std::tuple<Args...>&& tup
   ) {
     staticCheckCopyable<Args...>();
 
@@ -168,7 +168,7 @@ struct Param : runtime::component::Component<Param> {
 
   template <typename DataMsg>
   void sendDataMsg(
-    NodeType const& dest, HandlerType const& __attribute__((unused)) han,
+    NodeType const& dest, HandlerType const __attribute__((unused)) han,
     MsgSharedPtr<DataMsg> m
   ) {
     auto pmsg = promoteMsg(m.get());
diff --git a/src/vt/pipe/callback/cb_union/cb_raw.h b/src/vt/pipe/callback/cb_union/cb_raw.h
index ec1d8957d8..018e99a3fb 100644
--- a/src/vt/pipe/callback/cb_union/cb_raw.h
+++ b/src/vt/pipe/callback/cb_union/cb_raw.h
@@ -65,7 +65,7 @@ struct AnonCB : CallbackAnonTypeless { };
 struct SendMsgCB : CallbackSendTypeless {
   SendMsgCB() = default;
   SendMsgCB(
-    HandlerType const& in_handler, NodeType const& in_send_node
+    HandlerType const in_handler, NodeType const& in_send_node
   ) : CallbackSendTypeless(in_handler, in_send_node)
   { }
 };
@@ -73,7 +73,7 @@ struct SendMsgCB : CallbackSendTypeless {
 struct BcastMsgCB : CallbackBcastTypeless {
   BcastMsgCB() = default;
   BcastMsgCB(
-    HandlerType const& in_handler, bool const& in_include
+    HandlerType const in_handler, bool const& in_include
   ) : CallbackBcastTypeless(in_handler, in_include)
   { }
 };
@@ -89,8 +89,8 @@ struct BcastColMsgCB : CallbackProxyBcastTypeless {
 struct BcastColDirCB : CallbackProxyBcastDirect {
   BcastColDirCB() = default;
   BcastColDirCB(
-    HandlerType const& in_handler,
-    CallbackProxyBcastDirect::AutoHandlerType const& in_vrt_handler,
+    HandlerType const in_handler,
+    CallbackProxyBcastDirect::AutoHandlerType const in_vrt_handler,
     VirtualProxyType const& in_proxy
   ) : CallbackProxyBcastDirect(in_handler, in_vrt_handler, in_proxy)
   { }
diff --git a/src/vt/pipe/callback/cb_union/cb_raw_base.cc b/src/vt/pipe/callback/cb_union/cb_raw_base.cc
index c58a2bfd64..a128e81105 100644
--- a/src/vt/pipe/callback/cb_union/cb_raw_base.cc
+++ b/src/vt/pipe/callback/cb_union/cb_raw_base.cc
@@ -49,13 +49,13 @@
 namespace vt { namespace pipe { namespace callback { namespace cbunion {
 
 CallbackRawBaseSingle::CallbackRawBaseSingle(
-  RawSendMsgTagType, PipeType const& in_pipe, HandlerType const& in_handler,
+  RawSendMsgTagType, PipeType const& in_pipe, HandlerType const in_handler,
   NodeType const& in_node
 ) : pipe_(in_pipe), cb_(SendMsgCB{in_handler,in_node})
 { }
 
 CallbackRawBaseSingle::CallbackRawBaseSingle(
-  RawBcastMsgTagType, PipeType const& in_pipe, HandlerType const& in_handler,
+  RawBcastMsgTagType, PipeType const& in_pipe, HandlerType const in_handler,
   bool const& in_inc
 ) : pipe_(in_pipe), cb_(BcastMsgCB{in_handler,in_inc})
 { }
@@ -76,8 +76,8 @@ CallbackRawBaseSingle::CallbackRawBaseSingle(
 { }
 
 CallbackRawBaseSingle::CallbackRawBaseSingle(
-  RawBcastColDirTagType, PipeType const& in_pipe, HandlerType const& in_handler,
-  AutoHandlerType const& in_vrt, VirtualProxyType const& in_proxy
+  RawBcastColDirTagType, PipeType const& in_pipe, HandlerType const in_handler,
+  AutoHandlerType const in_vrt, VirtualProxyType const& in_proxy
 ) : pipe_(in_pipe), cb_(BcastColDirCB{in_handler, in_vrt, in_proxy})
 { }
 
diff --git a/src/vt/pipe/callback/cb_union/cb_raw_base.h b/src/vt/pipe/callback/cb_union/cb_raw_base.h
index cd0d5fd7e5..310da52ca1 100644
--- a/src/vt/pipe/callback/cb_union/cb_raw_base.h
+++ b/src/vt/pipe/callback/cb_union/cb_raw_base.h
@@ -85,11 +85,11 @@ struct CallbackRawBaseSingle {
 
   // Constructors for different types of callbacks
   CallbackRawBaseSingle(
-    RawSendMsgTagType, PipeType const& in_pipe, HandlerType const& in_handler,
+    RawSendMsgTagType, PipeType const& in_pipe, HandlerType const in_handler,
     NodeType const& in_node
   );
   CallbackRawBaseSingle(
-    RawBcastMsgTagType, PipeType const& in_pipe, HandlerType const& in_handler,
+    RawBcastMsgTagType, PipeType const& in_pipe, HandlerType const in_handler,
     bool const& in_inc
   );
   CallbackRawBaseSingle(RawAnonTagType, PipeType const& in_pipe);
@@ -97,12 +97,12 @@ struct CallbackRawBaseSingle {
   CallbackRawBaseSingle(RawBcastColMsgTagType, PipeType const& in_pipe);
   CallbackRawBaseSingle(
     RawBcastColDirTagType, PipeType const& in_pipe,
-    HandlerType const& in_handler, AutoHandlerType const& in_vrt,
+    HandlerType const in_handler, AutoHandlerType const in_vrt,
     VirtualProxyType const& in_proxy
   );
   CallbackRawBaseSingle(
     RawSendColDirTagType, PipeType const& in_pipe,
-    HandlerType const& in_handler, AutoHandlerType const& in_vrt_handler,
+    HandlerType const in_handler, AutoHandlerType const in_vrt_handler,
     void* index_bits
   );
   CallbackRawBaseSingle(
@@ -167,12 +167,12 @@ struct CallbackTyped : CallbackRawBaseSingle {
 
   // Forwarding constructors for different types of callbacks
   CallbackTyped(
-    RawSendMsgTagType, PipeType const& in_pipe, HandlerType const& in_handler,
+    RawSendMsgTagType, PipeType const& in_pipe, HandlerType const in_handler,
     NodeType const& in_node
   ) : CallbackRawBaseSingle(RawSendMsgTag,in_pipe,in_handler,in_node)
   { }
   CallbackTyped(
-    RawBcastMsgTagType, PipeType const& in_pipe, HandlerType const& in_handler,
+    RawBcastMsgTagType, PipeType const& in_pipe, HandlerType const in_handler,
     bool const& in_inc
   )  : CallbackRawBaseSingle(RawBcastMsgTag,in_pipe,in_handler,in_inc)
   { }
@@ -187,7 +187,7 @@ struct CallbackTyped : CallbackRawBaseSingle {
   { }
   CallbackTyped(
     RawBcastColDirTagType, PipeType const& in_pipe,
-    HandlerType const& in_handler, AutoHandlerType const& in_vrt,
+    HandlerType const in_handler, AutoHandlerType const in_vrt,
     VirtualProxyType const& in_proxy
   ) : CallbackRawBaseSingle(
         RawBcastColDirTag, in_pipe, in_handler, in_vrt, in_proxy
@@ -195,7 +195,7 @@ struct CallbackTyped : CallbackRawBaseSingle {
   { }
   CallbackTyped(
     RawSendColDirTagType, PipeType const& in_pipe,
-    HandlerType const& in_handler, AutoHandlerType const& in_vrt_handler,
+    HandlerType const in_handler, AutoHandlerType const in_vrt_handler,
     void* index_bits
   ) : CallbackRawBaseSingle(
         RawSendColDirTag,in_pipe,in_handler,in_vrt_handler,index_bits
diff --git a/src/vt/pipe/callback/handler_bcast/callback_bcast.h b/src/vt/pipe/callback/handler_bcast/callback_bcast.h
index 9c4f8dbfaa..460430320c 100644
--- a/src/vt/pipe/callback/handler_bcast/callback_bcast.h
+++ b/src/vt/pipe/callback/handler_bcast/callback_bcast.h
@@ -74,7 +74,7 @@ struct CallbackBcast : CallbackBase<signal::Signal<MsgT>> {
   CallbackBcast(CallbackBcast&&) = default;
 
   CallbackBcast(
-    HandlerType const& in_handler, bool const& in_include
+    HandlerType const in_handler, bool const& in_include
   );
 
   HandlerType getHandler() const { return handler_; }
diff --git a/src/vt/pipe/callback/handler_bcast/callback_bcast.impl.h b/src/vt/pipe/callback/handler_bcast/callback_bcast.impl.h
index c1760adc05..37af3d4e2f 100644
--- a/src/vt/pipe/callback/handler_bcast/callback_bcast.impl.h
+++ b/src/vt/pipe/callback/handler_bcast/callback_bcast.impl.h
@@ -59,7 +59,7 @@ namespace vt { namespace pipe { namespace callback {
 
 template <typename MsgT>
 CallbackBcast<MsgT>::CallbackBcast(
-  HandlerType const& in_handler, bool const& in_include
+  HandlerType const in_handler, bool const& in_include
 ) : handler_(in_handler), include_sender_(in_include)
 { }
 
diff --git a/src/vt/pipe/callback/handler_bcast/callback_bcast_tl.cc b/src/vt/pipe/callback/handler_bcast/callback_bcast_tl.cc
index 998aaac496..471881ec80 100644
--- a/src/vt/pipe/callback/handler_bcast/callback_bcast_tl.cc
+++ b/src/vt/pipe/callback/handler_bcast/callback_bcast_tl.cc
@@ -55,7 +55,7 @@
 namespace vt { namespace pipe { namespace callback {
 
 CallbackBcastTypeless::CallbackBcastTypeless(
-  HandlerType const& in_handler, bool const& in_include
+  HandlerType const in_handler, bool const& in_include
 ) : handler_(in_handler), include_sender_(in_include)
 { }
 
diff --git a/src/vt/pipe/callback/handler_bcast/callback_bcast_tl.h b/src/vt/pipe/callback/handler_bcast/callback_bcast_tl.h
index 2f646eeb80..ea47d47cda 100644
--- a/src/vt/pipe/callback/handler_bcast/callback_bcast_tl.h
+++ b/src/vt/pipe/callback/handler_bcast/callback_bcast_tl.h
@@ -60,7 +60,7 @@ struct CallbackBcastTypeless : CallbackBaseTL<CallbackBcastTypeless> {
   CallbackBcastTypeless& operator=(CallbackBcastTypeless const&) = default;
 
   CallbackBcastTypeless(
-    HandlerType const& in_handler, bool const& in_include
+    HandlerType const in_handler, bool const& in_include
   );
 
   HandlerType getHandler() const { return handler_; }
diff --git a/src/vt/pipe/callback/handler_send/callback_send.h b/src/vt/pipe/callback/handler_send/callback_send.h
index 3d337fd861..425aa890f5 100644
--- a/src/vt/pipe/callback/handler_send/callback_send.h
+++ b/src/vt/pipe/callback/handler_send/callback_send.h
@@ -76,7 +76,7 @@ struct CallbackSend : CallbackBase<signal::Signal<MsgT>> {
   CallbackSend(CallbackSend&&) = default;
 
   CallbackSend(
-    HandlerType const& in_handler, NodeType const& in_send_node
+    HandlerType const in_handler, NodeType const& in_send_node
   );
 
   HandlerType getHandler() const { return handler_; }
diff --git a/src/vt/pipe/callback/handler_send/callback_send.impl.h b/src/vt/pipe/callback/handler_send/callback_send.impl.h
index db16f7619e..e17beef029 100644
--- a/src/vt/pipe/callback/handler_send/callback_send.impl.h
+++ b/src/vt/pipe/callback/handler_send/callback_send.impl.h
@@ -56,7 +56,7 @@ namespace vt { namespace pipe { namespace callback {
 
 template <typename MsgT>
 CallbackSend<MsgT>::CallbackSend(
-  HandlerType const& in_handler, NodeType const& in_send_node
+  HandlerType const in_handler, NodeType const& in_send_node
 ) : send_node_(in_send_node), handler_(in_handler)
 { }
 
diff --git a/src/vt/pipe/callback/handler_send/callback_send_tl.cc b/src/vt/pipe/callback/handler_send/callback_send_tl.cc
index 56d143373c..86260fdf8a 100644
--- a/src/vt/pipe/callback/handler_send/callback_send_tl.cc
+++ b/src/vt/pipe/callback/handler_send/callback_send_tl.cc
@@ -54,7 +54,7 @@
 namespace vt { namespace pipe { namespace callback {
 
 CallbackSendTypeless::CallbackSendTypeless(
-  HandlerType const& in_handler, NodeType const& in_send_node
+  HandlerType const in_handler, NodeType const& in_send_node
 ) : send_node_(in_send_node), handler_(in_handler)
 { }
 
diff --git a/src/vt/pipe/callback/handler_send/callback_send_tl.h b/src/vt/pipe/callback/handler_send/callback_send_tl.h
index 7f32949bbb..420a6ea1f3 100644
--- a/src/vt/pipe/callback/handler_send/callback_send_tl.h
+++ b/src/vt/pipe/callback/handler_send/callback_send_tl.h
@@ -59,7 +59,7 @@ struct CallbackSendTypeless : CallbackBaseTL<CallbackSendTypeless> {
   CallbackSendTypeless& operator=(CallbackSendTypeless const&) = default;
 
   CallbackSendTypeless(
-    HandlerType const& in_handler, NodeType const& in_send_node
+    HandlerType const in_handler, NodeType const& in_send_node
   );
 
   template <typename SerializerT>
diff --git a/src/vt/pipe/callback/objgroup_bcast/callback_objgroup_bcast.h b/src/vt/pipe/callback/objgroup_bcast/callback_objgroup_bcast.h
index 1f83198b99..3fa7ee6706 100644
--- a/src/vt/pipe/callback/objgroup_bcast/callback_objgroup_bcast.h
+++ b/src/vt/pipe/callback/objgroup_bcast/callback_objgroup_bcast.h
@@ -55,7 +55,7 @@ namespace vt { namespace pipe { namespace callback {
 struct CallbackObjGroupBcast : CallbackBaseTL<CallbackObjGroupBcast> {
   CallbackObjGroupBcast() = default;
   CallbackObjGroupBcast(
-    HandlerType const& in_han, ObjGroupProxyType const& in_objgroup
+    HandlerType const in_han, ObjGroupProxyType const& in_objgroup
   ) : handler_(in_han), objgroup_(in_objgroup)
   { }
 
diff --git a/src/vt/pipe/callback/proxy_bcast/callback_proxy_bcast.h b/src/vt/pipe/callback/proxy_bcast/callback_proxy_bcast.h
index 316f35836b..ffc263c74e 100644
--- a/src/vt/pipe/callback/proxy_bcast/callback_proxy_bcast.h
+++ b/src/vt/pipe/callback/proxy_bcast/callback_proxy_bcast.h
@@ -68,7 +68,7 @@ struct CallbackProxyBcast : CallbackBase<signal::Signal<MsgT>> {
   CallbackProxyBcast(CallbackProxyBcast const&) = default;
   CallbackProxyBcast(CallbackProxyBcast&&) = default;
 
-  CallbackProxyBcast(HandlerType const& in_handler, ProxyType const& in_proxy)
+  CallbackProxyBcast(HandlerType const in_handler, ProxyType const& in_proxy)
     : proxy_(in_proxy), handler_(in_handler)
   { }
 
diff --git a/src/vt/pipe/callback/proxy_bcast/callback_proxy_bcast_tl.h b/src/vt/pipe/callback/proxy_bcast/callback_proxy_bcast_tl.h
index a591da0f1e..c5f7c70fd2 100644
--- a/src/vt/pipe/callback/proxy_bcast/callback_proxy_bcast_tl.h
+++ b/src/vt/pipe/callback/proxy_bcast/callback_proxy_bcast_tl.h
@@ -76,7 +76,7 @@ struct CallbackProxyBcastDirect : CallbackBaseTL<CallbackProxyBcastDirect> {
 
   CallbackProxyBcastDirect() = default;
   CallbackProxyBcastDirect(
-    HandlerType const& in_han, AutoHandlerType const& in_vrt,
+    HandlerType const in_han, AutoHandlerType const in_vrt,
     VirtualProxyType const& in_proxy
   ) : vrt_dispatch_han_(in_vrt), handler_(in_han), proxy_(in_proxy)
   { }
diff --git a/src/vt/pipe/callback/proxy_send/callback_proxy_send.h b/src/vt/pipe/callback/proxy_send/callback_proxy_send.h
index cdee8e2dd9..faa6be70af 100644
--- a/src/vt/pipe/callback/proxy_send/callback_proxy_send.h
+++ b/src/vt/pipe/callback/proxy_send/callback_proxy_send.h
@@ -68,13 +68,13 @@ struct CallbackProxySend : CallbackBase<signal::Signal<MsgT>> {
   using MessageType      = MsgT;
 
   CallbackProxySend(
-    HandlerType const& in_handler, IndexedProxyType const& in_proxy
+    HandlerType const in_handler, IndexedProxyType const& in_proxy
   ) : proxy_(in_proxy.getCollectionProxy()),
       idx_(in_proxy.getElementProxy().getIndex()), handler_(in_handler)
   { }
 
   CallbackProxySend(
-    HandlerType const& in_handler, ProxyType const& in_proxy,
+    HandlerType const in_handler, ProxyType const& in_proxy,
     IndexType const& in_idx
   ) : proxy_(in_proxy), idx_(in_idx), handler_(in_handler)
   { }
diff --git a/src/vt/pipe/callback/proxy_send/callback_proxy_send_tl.h b/src/vt/pipe/callback/proxy_send/callback_proxy_send_tl.h
index ed37b30544..eef23047bd 100644
--- a/src/vt/pipe/callback/proxy_send/callback_proxy_send_tl.h
+++ b/src/vt/pipe/callback/proxy_send/callback_proxy_send_tl.h
@@ -75,7 +75,7 @@ struct CallbackProxySendDirect : CallbackBaseTL<CallbackProxySendDirect> {
   using AutoHandlerType = auto_registry::AutoHandlerType;
 
   CallbackProxySendDirect() = default;
-  CallbackProxySendDirect(HandlerType const& in_han, AutoHandlerType in_vrt)
+  CallbackProxySendDirect(HandlerType const in_han, AutoHandlerType in_vrt)
     : vrt_dispatch_han_(in_vrt), handler_(in_han)
   { }
 
diff --git a/src/vt/registry/auto/auto_registry.h b/src/vt/registry/auto/auto_registry.h
index a1587cac58..0263249494 100644
--- a/src/vt/registry/auto/auto_registry.h
+++ b/src/vt/registry/auto/auto_registry.h
@@ -62,7 +62,7 @@
 
 namespace vt { namespace auto_registry {
 
-AutoActiveType getAutoHandler(HandlerType const& handler);
+AutoActiveType getAutoHandler(HandlerType const handler);
 
 AutoActiveObjGroupType getAutoHandlerObjGroup(HandlerType han);
 AutoHandlerType getAutoHandlerObjTypeIdx(HandlerType han);
diff --git a/src/vt/registry/auto/auto_registry_impl.h b/src/vt/registry/auto/auto_registry_impl.h
index 975d112517..fa49e77c12 100644
--- a/src/vt/registry/auto/auto_registry_impl.h
+++ b/src/vt/registry/auto/auto_registry_impl.h
@@ -57,12 +57,14 @@ namespace vt { namespace auto_registry {
 
 inline AutoActiveObjGroupType getAutoHandlerObjGroup(HandlerType han) {
   using ContainerType = AutoActiveObjGroupContainerType;
+
   auto const id = HandlerManagerType::getHandlerIdentifier(han);
   return getAutoRegistryGen<ContainerType>().at(id).getFun();
 }
 
 inline AutoHandlerType getAutoHandlerObjTypeIdx(HandlerType han) {
   using ContainerType = AutoActiveObjGroupContainerType;
+
   auto const id = HandlerManagerType::getHandlerIdentifier(han);
   return getAutoRegistryGen<ContainerType>().at(id).getObjIdx();
 }
@@ -114,10 +116,10 @@ inline HandlerType makeAutoHandlerParam() {
   return HandlerManagerType::makeHandler(is_auto, is_functor, RunType::idx);
 }
 
-inline AutoActiveType getAutoHandler(HandlerType const& handler) {
-  auto const& han_id = HandlerManagerType::getHandlerIdentifier(handler);
-  bool const& is_auto = HandlerManagerType::isHandlerAuto(handler);
-  bool const& is_functor = HandlerManagerType::isHandlerFunctor(handler);
+inline AutoActiveType getAutoHandler(HandlerType const handler) {
+  auto const han_id = HandlerManagerType::getHandlerIdentifier(handler);
+  bool const is_auto = HandlerManagerType::isHandlerAuto(handler);
+  bool const is_functor = HandlerManagerType::isHandlerFunctor(handler);
 
   vt_debug_print(
     handler, node,
diff --git a/src/vt/registry/auto/auto_registry_interface.h b/src/vt/registry/auto/auto_registry_interface.h
index 7309db2601..881761a2e2 100644
--- a/src/vt/registry/auto/auto_registry_interface.h
+++ b/src/vt/registry/auto/auto_registry_interface.h
@@ -60,9 +60,9 @@ HandlerType makeAutoHandlerParam();
 template <typename T, bool is_msg, typename... Args>
 HandlerType makeAutoHandlerFunctor();
 
-AutoActiveType getAutoHandler(HandlerType const& handler);
+AutoActiveType getAutoHandler(HandlerType const handler);
 
-AutoActiveFunctorType getAutoHandlerFunctor(HandlerType const& handler);
+AutoActiveFunctorType getAutoHandlerFunctor(HandlerType const handler);
 
 #if vt_check_enabled(trace_enabled)
   trace::TraceEntryIDType handlerTraceID(
diff --git a/src/vt/registry/auto/collection/auto_registry_collection.h b/src/vt/registry/auto/collection/auto_registry_collection.h
index 0fe15a79e4..619c43ff76 100644
--- a/src/vt/registry/auto/collection/auto_registry_collection.h
+++ b/src/vt/registry/auto/collection/auto_registry_collection.h
@@ -56,13 +56,13 @@ namespace vt { namespace auto_registry {
 
 using namespace ::vt::vrt::collection;
 
-AutoActiveCollectionType getAutoHandlerCollection(HandlerType const& handler);
+AutoActiveCollectionType getAutoHandlerCollection(HandlerType const handler);
 
 template <typename ColT, typename MsgT, ActiveColTypedFnType<MsgT, ColT>* f>
 HandlerType makeAutoHandlerCollection();
 
 AutoActiveCollectionMemType getAutoHandlerCollectionMem(
-  HandlerType const& handler
+  HandlerType const handler
 );
 
 template <
diff --git a/src/vt/registry/auto/collection/auto_registry_collection.impl.h b/src/vt/registry/auto/collection/auto_registry_collection.impl.h
index 384e5d7eb3..466bb07d68 100644
--- a/src/vt/registry/auto/collection/auto_registry_collection.impl.h
+++ b/src/vt/registry/auto/collection/auto_registry_collection.impl.h
@@ -51,7 +51,7 @@
 namespace vt { namespace auto_registry {
 
 inline AutoActiveCollectionType getAutoHandlerCollection(
-  HandlerType const& handler
+  HandlerType const handler
 ) {
   using ContainerType = AutoActiveCollectionContainerType;
 
@@ -74,7 +74,7 @@ inline HandlerType makeAutoHandlerCollection() {
 }
 
 inline AutoActiveCollectionMemType getAutoHandlerCollectionMem(
-  HandlerType const& handler
+  HandlerType const handler
 ) {
   using ContainerType = AutoActiveCollectionMemContainerType;
 
diff --git a/src/vt/registry/auto/functor/auto_registry_functor.h b/src/vt/registry/auto/functor/auto_registry_functor.h
index ff822fcdc1..4224e4fb04 100644
--- a/src/vt/registry/auto/functor/auto_registry_functor.h
+++ b/src/vt/registry/auto/functor/auto_registry_functor.h
@@ -61,8 +61,8 @@ struct RegistrarFunctor {
   RegistrarFunctor();
 };
 
-AutoActiveFunctorType getAutoHandlerFunctor(HandlerType const& handler);
-NumArgsType getAutoHandlerFunctorArgs(HandlerType const& handler);
+AutoActiveFunctorType getAutoHandlerFunctor(HandlerType const handler);
+NumArgsType getAutoHandlerFunctorArgs(HandlerType const handler);
 
 template <typename FunctorT, bool is_msg, typename... Args>
 HandlerType makeAutoHandlerFunctor();
diff --git a/src/vt/registry/auto/functor/auto_registry_functor_impl.h b/src/vt/registry/auto/functor/auto_registry_functor_impl.h
index a3109104e0..bd710bb229 100644
--- a/src/vt/registry/auto/functor/auto_registry_functor_impl.h
+++ b/src/vt/registry/auto/functor/auto_registry_functor_impl.h
@@ -84,7 +84,7 @@ RegistrarFunctor<RunnableT, RegT, InfoT, FnT>::RegistrarFunctor() {
   // trace
   std::string event_type_name = AdapterType::traceGetEventType();
   std::string event_name = AdapterType::traceGetEventName();
-  auto const& trace_ep = trace::TraceRegistry::registerEventHashed(
+  auto const trace_ep = trace::TraceRegistry::registerEventHashed(
     event_type_name, event_name);
   reg.emplace_back(InfoT{NumArgsTag, fn, trace_ep, num_args});
   #else
@@ -93,17 +93,17 @@ RegistrarFunctor<RunnableT, RegT, InfoT, FnT>::RegistrarFunctor() {
   #endif
 }
 
-inline NumArgsType getAutoHandlerFunctorArgs(HandlerType const& han) {
-  auto const& id = HandlerManagerType::getHandlerIdentifier(han);
+inline NumArgsType getAutoHandlerFunctorArgs(HandlerType const han) {
+  auto const id = HandlerManagerType::getHandlerIdentifier(han);
 
   using ContainerType = AutoActiveFunctorContainerType;
   return getAutoRegistryGen<ContainerType>().at(id).getNumArgs();
 }
 
-inline AutoActiveFunctorType getAutoHandlerFunctor(HandlerType const& han) {
-  auto const& id = HandlerManagerType::getHandlerIdentifier(han);
-  bool const& is_auto = HandlerManagerType::isHandlerAuto(han);
-  bool const& is_functor = HandlerManagerType::isHandlerFunctor(han);
+inline AutoActiveFunctorType getAutoHandlerFunctor(HandlerType const han) {
+  auto const id = HandlerManagerType::getHandlerIdentifier(han);
+  bool const is_auto = HandlerManagerType::isHandlerAuto(han);
+  bool const is_functor = HandlerManagerType::isHandlerFunctor(han);
 
   vt_debug_print(
     handler, node,
diff --git a/src/vt/registry/auto/map/auto_registry_map.h b/src/vt/registry/auto/map/auto_registry_map.h
index bfc1bf9566..35f337075c 100644
--- a/src/vt/registry/auto/map/auto_registry_map.h
+++ b/src/vt/registry/auto/map/auto_registry_map.h
@@ -56,24 +56,24 @@ namespace vt { namespace auto_registry {
 
 using namespace mapping;
 
-AutoActiveMapFunctorType getAutoHandlerFunctorMap(HandlerType const& han);
+AutoActiveMapFunctorType getAutoHandlerFunctorMap(HandlerType const han);
 
 template <typename FunctorT, typename... Args>
 HandlerType makeAutoHandlerFunctorMap();
 
 // Registration for collection index mapping functions
-AutoActiveMapType getAutoHandlerMap(HandlerType const& handler);
+AutoActiveMapType getAutoHandlerMap(HandlerType const handler);
 
 template <typename IndexT, ActiveMapTypedFnType<IndexT>* f>
 HandlerType makeAutoHandlerMap();
 
 // Registration for seed mapping singletons
-AutoActiveSeedMapType getAutoHandlerSeedMap(HandlerType const& handler);
+AutoActiveSeedMapType getAutoHandlerSeedMap(HandlerType const handler);
 
 template <ActiveSeedMapFnType* f>
 HandlerType makeAutoHandlerSeedMap();
 
-AutoActiveMapType getHandlerMap(HandlerType const& han);
+AutoActiveMapType getHandlerMap(HandlerType const han);
 
 }} // end namespace vt::auto_registry
 
diff --git a/src/vt/registry/auto/map/auto_registry_map_impl.h b/src/vt/registry/auto/map/auto_registry_map_impl.h
index e73dd6637d..2c1724cc36 100644
--- a/src/vt/registry/auto/map/auto_registry_map_impl.h
+++ b/src/vt/registry/auto/map/auto_registry_map_impl.h
@@ -81,12 +81,12 @@ inline HandlerType makeAutoHandlerFunctorMap() {
 }
 
 inline AutoActiveMapFunctorType getAutoHandlerFunctorMap(
-  HandlerType const& han
+  HandlerType const han
 ) {
   using ContainerType = AutoActiveMapFunctorContainerType;
-  auto const& id = HandlerManagerType::getHandlerIdentifier(han);
-  bool const& is_auto = HandlerManagerType::isHandlerAuto(han);
-  bool const& is_functor = HandlerManagerType::isHandlerFunctor(han);
+  auto const id = HandlerManagerType::getHandlerIdentifier(han);
+  bool const is_auto = HandlerManagerType::isHandlerAuto(han);
+  bool const is_functor = HandlerManagerType::isHandlerFunctor(han);
 
   vt_debug_print(
     handler, node,
@@ -120,9 +120,9 @@ inline HandlerType makeAutoHandlerMap() {
   return han;
 }
 
-inline AutoActiveMapType getAutoHandlerMap(HandlerType const& handler) {
+inline AutoActiveMapType getAutoHandlerMap(HandlerType const handler) {
   using ContainerType = AutoActiveMapContainerType;
-  auto const& id = HandlerManagerType::getHandlerIdentifier(handler);
+  auto const id = HandlerManagerType::getHandlerIdentifier(handler);
   vt_debug_print(
     handler, node,
     "getAutoHandlerMap: id={}, handler={}\n", id, handler
@@ -146,9 +146,9 @@ inline HandlerType makeAutoHandlerSeedMap() {
 }
 
 // Registration for seed mapping singletons
-inline AutoActiveSeedMapType getAutoHandlerSeedMap(HandlerType const& handler) {
+inline AutoActiveSeedMapType getAutoHandlerSeedMap(HandlerType const handler) {
   using ContainerType = AutoActiveSeedMapContainerType;
-  auto const& id = HandlerManagerType::getHandlerIdentifier(handler);
+  auto const id = HandlerManagerType::getHandlerIdentifier(handler);
   vt_debug_print(
     handler, node,
     "getAutoHandlerSeedMap: id={}, handler={}\n", id, handler
@@ -156,8 +156,8 @@ inline AutoActiveSeedMapType getAutoHandlerSeedMap(HandlerType const& handler) {
   return getAutoRegistryGen<ContainerType>().at(id).getFun();
 }
 
-inline AutoActiveMapType getHandlerMap(HandlerType const& han) {
-  bool const& is_functor = HandlerManagerType::isHandlerFunctor(han);
+inline AutoActiveMapType getHandlerMap(HandlerType const han) {
+  bool const is_functor = HandlerManagerType::isHandlerFunctor(han);
   if (is_functor) {
     return getAutoHandlerFunctorMap(han);
   } else {
diff --git a/src/vt/registry/auto/rdma/auto_registry_rdma.h b/src/vt/registry/auto/rdma/auto_registry_rdma.h
index 4cece36f58..6ca39dd052 100644
--- a/src/vt/registry/auto/rdma/auto_registry_rdma.h
+++ b/src/vt/registry/auto/rdma/auto_registry_rdma.h
@@ -54,8 +54,8 @@
 
 namespace vt { namespace auto_registry {
 
-AutoActiveRDMAGetType getAutoHandlerRDMAGet(HandlerType const& handler);
-AutoActiveRDMAPutType getAutoHandlerRDMAPut(HandlerType const& handler);
+AutoActiveRDMAGetType getAutoHandlerRDMAGet(HandlerType const handler);
+AutoActiveRDMAPutType getAutoHandlerRDMAPut(HandlerType const handler);
 
 template <typename MsgT, ActiveTypedRDMAPutFnType<MsgT>* f>
 HandlerType makeAutoHandlerRDMAPut();
diff --git a/src/vt/registry/auto/rdma/auto_registry_rdma.impl.h b/src/vt/registry/auto/rdma/auto_registry_rdma.impl.h
index 6cd3ff089a..ea232ecc96 100644
--- a/src/vt/registry/auto/rdma/auto_registry_rdma.impl.h
+++ b/src/vt/registry/auto/rdma/auto_registry_rdma.impl.h
@@ -52,7 +52,7 @@
 
 namespace vt { namespace auto_registry {
 
-inline AutoActiveRDMAPutType getAutoHandlerRDMAPut(HandlerType const& handler) {
+inline AutoActiveRDMAPutType getAutoHandlerRDMAPut(HandlerType const handler) {
   using ContainerType = AutoActiveRDMAPutContainerType;
 
   auto const han_id = HandlerManager::getHandlerIdentifier(handler);
@@ -71,7 +71,7 @@ inline HandlerType makeAutoHandlerRDMAPut() {
   return HandlerManager::makeHandler(false, false, id);
 }
 
-inline AutoActiveRDMAGetType getAutoHandlerRDMAGet(HandlerType const& handler) {
+inline AutoActiveRDMAGetType getAutoHandlerRDMAGet(HandlerType const handler) {
   using ContainerType = AutoActiveRDMAGetContainerType;
 
   auto const han_id = HandlerManager::getHandlerIdentifier(handler);
diff --git a/src/vt/registry/auto/vc/auto_registry_vc.h b/src/vt/registry/auto/vc/auto_registry_vc.h
index e71fb35dd8..fd30e57d3b 100644
--- a/src/vt/registry/auto/vc/auto_registry_vc.h
+++ b/src/vt/registry/auto/vc/auto_registry_vc.h
@@ -56,7 +56,7 @@ namespace vt { namespace auto_registry {
 
 using namespace vrt;
 
-AutoActiveVCType getAutoHandlerVC(HandlerType const& handler);
+AutoActiveVCType getAutoHandlerVC(HandlerType const handler);
 
 template <typename VrtT, typename MsgT, ActiveVrtTypedFnType<MsgT, VrtT>* f>
 HandlerType makeAutoHandlerVC();
diff --git a/src/vt/registry/auto/vc/auto_registry_vc_impl.h b/src/vt/registry/auto/vc/auto_registry_vc_impl.h
index 194f0014ef..eebc98f8b9 100644
--- a/src/vt/registry/auto/vc/auto_registry_vc_impl.h
+++ b/src/vt/registry/auto/vc/auto_registry_vc_impl.h
@@ -67,7 +67,7 @@ inline HandlerType makeAutoHandlerVC() {
   return HandlerManager::makeHandler(false, false, id);
 }
 
-inline AutoActiveVCType getAutoHandlerVC(HandlerType const& handler) {
+inline AutoActiveVCType getAutoHandlerVC(HandlerType const handler) {
   using ContainerType = AutoActiveVCContainerType;
 
   auto const han_id = HandlerManager::getHandlerIdentifier(handler);
diff --git a/src/vt/registry/registry.cc b/src/vt/registry/registry.cc
index d13a9b6b0b..db0ef25ee9 100644
--- a/src/vt/registry/registry.cc
+++ b/src/vt/registry/registry.cc
@@ -66,7 +66,7 @@ HandlerType Registry::registerNewHandler(
 }
 
 void Registry::swapHandler(
-  HandlerType const& han, ActiveClosureFnType fn, TagType const& tag
+  HandlerType const han, ActiveClosureFnType fn, TagType const& tag
 ) {
   if (tag == no_tag) {
     auto iter = registered_.find(han);
@@ -90,7 +90,7 @@ void Registry::swapHandler(
 }
 
 void Registry::unregisterHandlerFn(
-  HandlerType const& han, TagType const& tag
+  HandlerType const han, TagType const& tag
 ) {
   swapHandler(han, nullptr, tag);
 }
@@ -101,7 +101,7 @@ HandlerType Registry::registerActiveHandler(
   return registerNewHandler(fn, tag, true);
 }
 
-ActiveClosureFnType Registry::getHandlerNoTag(HandlerType const& han) {
+ActiveClosureFnType Registry::getHandlerNoTag(HandlerType const han) {
   auto iter = registered_.find(han);
   if (iter != registered_.end()) {
     return iter->second;
@@ -111,7 +111,7 @@ ActiveClosureFnType Registry::getHandlerNoTag(HandlerType const& han) {
 }
 
 ActiveClosureFnType Registry::getHandler(
-  HandlerType const& han, TagType const& tag
+  HandlerType const han, TagType const& tag
 ) {
   if (tag == no_tag) {
     return getHandlerNoTag(han);
diff --git a/src/vt/registry/registry.h b/src/vt/registry/registry.h
index b670797eb9..c48773e873 100644
--- a/src/vt/registry/registry.h
+++ b/src/vt/registry/registry.h
@@ -97,7 +97,7 @@ struct Registry : runtime::component::Component<Registry> {
    * \param[in] tag relevant message tag for delivery
    */
   void unregisterHandlerFn(
-    HandlerType const& han, TagType const& tag = no_tag
+    HandlerType const han, TagType const& tag = no_tag
   );
 
   /**
@@ -108,7 +108,7 @@ struct Registry : runtime::component::Component<Registry> {
    * \param[in] tag tag to associate
    */
   void swapHandler(
-    HandlerType const& han, ActiveClosureFnType fn, TagType const& tag = no_tag
+    HandlerType const han, ActiveClosureFnType fn, TagType const& tag = no_tag
   );
 
   /**
@@ -132,7 +132,7 @@ struct Registry : runtime::component::Component<Registry> {
    * \return the active function
    */
   ActiveClosureFnType getHandler(
-    HandlerType const& han, TagType const& tag = no_tag
+    HandlerType const han, TagType const& tag = no_tag
   );
 
   /**
@@ -142,7 +142,7 @@ struct Registry : runtime::component::Component<Registry> {
    *
    * \return the active function
    */
-  ActiveClosureFnType getHandlerNoTag(HandlerType const& han);
+  ActiveClosureFnType getHandlerNoTag(HandlerType const han);
 
 private:
   ContainerType registered_;
diff --git a/src/vt/topos/location/message/msg.h b/src/vt/topos/location/message/msg.h
index 474fa7a7fa..79a14652e3 100644
--- a/src/vt/topos/location/message/msg.h
+++ b/src/vt/topos/location/message/msg.h
@@ -103,7 +103,7 @@ struct EntityMsg : ActiveMessageT {
   void setLocInst(LocInstType const& inst) { loc_man_inst_ = inst; }
   LocInstType getLocInst() const { return loc_man_inst_;  }
   bool hasHandler() const { return handler_ != uninitialized_handler; }
-  void setHandler(HandlerType const& han) { handler_ = han; }
+  void setHandler(HandlerType const han) { handler_ = han; }
   HandlerType getHandler() const { return handler_; }
   void setSerialize(bool const is_serialize) { serialize_ = is_serialize; }
   bool getSerialize() const { return serialize_; }
diff --git a/src/vt/vrt/collection/dispatch/registry.h b/src/vt/vrt/collection/dispatch/registry.h
index cf90072a63..48941a359e 100644
--- a/src/vt/vrt/collection/dispatch/registry.h
+++ b/src/vt/vrt/collection/dispatch/registry.h
@@ -81,7 +81,7 @@ struct VrtDispatchHolder {
 template <typename MsgT, typename ColT>
 inline AutoHandlerType registerVrtDispatch();
 
-inline DispatchBasePtrType getDispatch(AutoHandlerType const& han);
+inline DispatchBasePtrType getDispatch(AutoHandlerType const han);
 
 template <typename MsgT, typename ColT>
 inline AutoHandlerType makeVrtDispatch(
diff --git a/src/vt/vrt/collection/dispatch/registry.impl.h b/src/vt/vrt/collection/dispatch/registry.impl.h
index c254be6de1..05149317ec 100644
--- a/src/vt/vrt/collection/dispatch/registry.impl.h
+++ b/src/vt/vrt/collection/dispatch/registry.impl.h
@@ -75,7 +75,7 @@ template <typename MsgT, typename ColT>
 AutoHandlerType const VrtDispatchHolder<MsgT,ColT>::idx =
   registerVrtDispatch<MsgT,ColT>();
 
-inline DispatchBasePtrType getDispatch(AutoHandlerType const& han) {
+inline DispatchBasePtrType getDispatch(AutoHandlerType const han) {
   return getTLRegistry().at(han).get();
 }
 
diff --git a/src/vt/vrt/collection/holders/col_holder.h b/src/vt/vrt/collection/holders/col_holder.h
index 5095244795..d79db8748d 100644
--- a/src/vt/vrt/collection/holders/col_holder.h
+++ b/src/vt/vrt/collection/holders/col_holder.h
@@ -73,7 +73,7 @@ struct CollectionHolder : BaseHolder {
    * \param[in] in_is_static whether the collection is static
    */
   CollectionHolder(
-    HandlerType const& in_map_fn, IndexT const& idx, bool const in_is_static
+    HandlerType const in_map_fn, IndexT const& idx, bool const in_is_static
   );
   virtual ~CollectionHolder() {}
 
diff --git a/src/vt/vrt/collection/holders/col_holder.impl.h b/src/vt/vrt/collection/holders/col_holder.impl.h
index 93b65d4188..03a7377cd9 100644
--- a/src/vt/vrt/collection/holders/col_holder.impl.h
+++ b/src/vt/vrt/collection/holders/col_holder.impl.h
@@ -52,7 +52,7 @@ namespace vt { namespace vrt { namespace collection {
 
 template <typename ColT, typename IndexT>
 CollectionHolder<ColT, IndexT>::CollectionHolder(
-  HandlerType const& in_map_fn, IndexT const& idx, bool const in_is_static
+  HandlerType const in_map_fn, IndexT const& idx, bool const in_is_static
 ) : is_static_(in_is_static), map_fn(in_map_fn), max_idx(idx)
 { }
 
diff --git a/src/vt/vrt/collection/holders/elm_holder.h b/src/vt/vrt/collection/holders/elm_holder.h
index 4eec1da8cf..8bad5224f2 100644
--- a/src/vt/vrt/collection/holders/elm_holder.h
+++ b/src/vt/vrt/collection/holders/elm_holder.h
@@ -59,7 +59,7 @@ struct ElementHolder {
   using VirtualPtrType = std::unique_ptr<CollectionBase<ColT,IndexT>>;
 
   ElementHolder(
-    VirtualPtrType in_vc_ptr_, HandlerType const& in_han, IndexT const& idx
+    VirtualPtrType in_vc_ptr_, HandlerType const in_han, IndexT const& idx
   );
   ElementHolder(ElementHolder&&) = default;
 
diff --git a/src/vt/vrt/collection/holders/elm_holder.impl.h b/src/vt/vrt/collection/holders/elm_holder.impl.h
index b14d0149f2..8d1c45bbe5 100644
--- a/src/vt/vrt/collection/holders/elm_holder.impl.h
+++ b/src/vt/vrt/collection/holders/elm_holder.impl.h
@@ -58,7 +58,7 @@ namespace vt { namespace vrt { namespace collection {
 
 template <typename ColT, typename IndexT>
 ElementHolder<ColT, IndexT>::ElementHolder(
-  VirtualPtrType in_vc_ptr_, HandlerType const& in_han, IndexT const& idx
+  VirtualPtrType in_vc_ptr_, HandlerType const in_han, IndexT const& idx
 ) : vc_ptr_(std::move(in_vc_ptr_)), map_fn(in_han), max_idx(idx)
 { }
 
diff --git a/src/vt/vrt/collection/holders/entire_holder.h b/src/vt/vrt/collection/holders/entire_holder.h
index 56f9f65d7a..0c1095b857 100644
--- a/src/vt/vrt/collection/holders/entire_holder.h
+++ b/src/vt/vrt/collection/holders/entire_holder.h
@@ -60,7 +60,7 @@ struct UniversalIndexHolder {
   static void destroyAllLive();
   static void destroyCollection(VirtualProxyType const proxy);
   static void insertMap(
-    VirtualProxyType const proxy, HandlerType const& han,
+    VirtualProxyType const proxy, HandlerType const han,
     EpochType const& insert_epoch = no_epoch
   );
   static HandlerType getMap(VirtualProxyType const proxy);
diff --git a/src/vt/vrt/collection/holders/entire_holder.impl.h b/src/vt/vrt/collection/holders/entire_holder.impl.h
index 0e835f5f99..d51a32cfbc 100644
--- a/src/vt/vrt/collection/holders/entire_holder.impl.h
+++ b/src/vt/vrt/collection/holders/entire_holder.impl.h
@@ -76,7 +76,7 @@ template <typename always_void_>
 
 template <typename always_void_>
 /*static*/ void UniversalIndexHolder<always_void_>::insertMap(
-  VirtualProxyType const proxy, HandlerType const& han,
+  VirtualProxyType const proxy, HandlerType const han,
   EpochType const& insert_epoch
 ) {
   live_collections_map_.emplace(
diff --git a/src/vt/vrt/collection/manager.cc b/src/vt/vrt/collection/manager.cc
index e61446c3b3..0ffc8ad153 100644
--- a/src/vt/vrt/collection/manager.cc
+++ b/src/vt/vrt/collection/manager.cc
@@ -80,7 +80,7 @@ void CollectionManager::startup() {
 }
 
 DispatchBasePtrType
-getDispatcher(auto_registry::AutoHandlerType const& han) {
+getDispatcher(auto_registry::AutoHandlerType const han) {
   return theCollection()->getDispatcher(han);
 }
 
diff --git a/src/vt/vrt/collection/manager.fwd.h b/src/vt/vrt/collection/manager.fwd.h
index 7d0fbc19b6..b74732c55f 100644
--- a/src/vt/vrt/collection/manager.fwd.h
+++ b/src/vt/vrt/collection/manager.fwd.h
@@ -53,7 +53,7 @@ namespace vt { namespace vrt { namespace collection {
 
 struct CollectionManager;
 
-DispatchBasePtrType getDispatcher(auto_registry::AutoHandlerType const& han);
+DispatchBasePtrType getDispatcher(auto_registry::AutoHandlerType const han);
 
 }}} /* end namespace vt::vrt::collection */
 
diff --git a/src/vt/vrt/collection/manager.h b/src/vt/vrt/collection/manager.h
index 3e3c47df1c..3035eb8b23 100644
--- a/src/vt/vrt/collection/manager.h
+++ b/src/vt/vrt/collection/manager.h
@@ -192,7 +192,7 @@ struct CollectionManager
   template <typename ColT, typename... Args>
   CollectionProxyWrapType<ColT, typename ColT::IndexType>
   constructMap(
-    typename ColT::IndexType range, HandlerType const& map,
+    typename ColT::IndexType range, HandlerType const map,
     Args&&... args
   );
 
@@ -332,7 +332,7 @@ struct CollectionManager
   template <typename ColT>
   CollectionProxyWrapType<ColT> constructCollectiveMap(
     typename ColT::IndexType range, DistribConstructFn<ColT> cons_fn,
-    HandlerType const& map_han, TagType const& tag
+    HandlerType const map_han, TagType const& tag
   );
 
 private:
@@ -420,7 +420,7 @@ struct CollectionManager
    */
   template <typename ColT>
   InsertToken<ColT> constructInsertMap(
-    typename ColT::IndexType range, HandlerType const& map_han, TagType const& tag
+    typename ColT::IndexType range, HandlerType const map_han, TagType const& tag
   );
 
   /**
@@ -553,7 +553,7 @@ struct CollectionManager
   >
   messaging::PendingSend sendMsgUntypedHandler(
     VirtualElmProxyType<ColT> const& proxy, MsgT* msg,
-    HandlerType const& handler, bool imm_context = true
+    HandlerType const handler, bool imm_context = true
   );
 
   /**
@@ -570,7 +570,7 @@ struct CollectionManager
   template <typename MsgT, typename ColT>
   IsNotColMsgType<MsgT> sendMsgWithHan(
     VirtualElmProxyType<ColT> const& proxy, MsgT* msg,
-    HandlerType const& handler
+    HandlerType const handler
   );
 
   /**
@@ -586,7 +586,7 @@ struct CollectionManager
   template <typename MsgT, typename ColT>
   IsColMsgType<MsgT> sendMsgWithHan(
     VirtualElmProxyType<ColT> const& proxy, MsgT* msg,
-    HandlerType const& handler
+    HandlerType const handler
   );
 
   /**
@@ -602,7 +602,7 @@ struct CollectionManager
   template <typename MsgT, typename ColT>
   messaging::PendingSend sendNormalMsg(
     VirtualElmProxyType<ColT> const& proxy, MsgT* msg,
-    HandlerType const& handler
+    HandlerType const handler
   );
 
   /**
@@ -881,7 +881,7 @@ struct CollectionManager
   template <typename MsgT, typename ColT>
   IsNotColMsgType<MsgT> broadcastMsgWithHan(
     CollectionProxyWrapType<ColT> const& proxy, MsgT* msg,
-    HandlerType const& handler, bool instrument = true
+    HandlerType const handler, bool instrument = true
   );
 
   /**
@@ -896,7 +896,7 @@ struct CollectionManager
   template <typename MsgT, typename ColT>
   IsColMsgType<MsgT> broadcastMsgWithHan(
     CollectionProxyWrapType<ColT> const& proxy, MsgT* msg,
-    HandlerType const& handler, bool instrument = true
+    HandlerType const handler, bool instrument = true
   );
 
   /**
@@ -913,7 +913,7 @@ struct CollectionManager
   template <typename MsgT, typename ColT>
   messaging::PendingSend broadcastNormalMsg(
     CollectionProxyWrapType<ColT> const& proxy, MsgT* msg,
-    HandlerType const& handler, bool instrument = true
+    HandlerType const handler, bool instrument = true
   );
 
   /**
@@ -930,7 +930,7 @@ struct CollectionManager
   template <typename MsgT, typename ColT, typename IdxT>
   messaging::PendingSend broadcastMsgUntypedHandler(
     CollectionProxyWrapType<ColT, IdxT> const& proxy, MsgT* msg,
-    HandlerType const& handler, bool instrument
+    HandlerType const handler, bool instrument
   );
 
   /**
@@ -1358,7 +1358,7 @@ struct CollectionManager
   template <typename ColT, typename IndexT = typename ColT::IndexType>
   bool insertCollectionElement(
     VirtualPtrType<ColT, IndexT> vc, IndexT const& idx, IndexT const& max_idx,
-    HandlerType const& map_han, VirtualProxyType const& proxy,
+    HandlerType const map_han, VirtualProxyType const& proxy,
     bool const is_static, NodeType const& home_node,
     bool const& is_migrated_in = false,
     NodeType const& migrated_from = uninitialized_destination
@@ -1438,7 +1438,7 @@ struct CollectionManager
    * \param[in] insert_epoch insert epoch for dynamic insertions
    */
   void insertCollectionInfo(
-    VirtualProxyType const& proxy, HandlerType const& map,
+    VirtualProxyType const& proxy, HandlerType const map,
     EpochType const& insert_epoch = no_epoch
   );
 
@@ -1662,7 +1662,7 @@ struct CollectionManager
   MigrateStatus migrateIn(
     VirtualProxyType const& proxy, IndexT const& idx, NodeType const& from,
     VirtualPtrType<ColT, IndexT> vrt_elm_ptr, IndexT const& range,
-    HandlerType const& map_han
+    HandlerType const map_han
   );
 
 public:
diff --git a/src/vt/vrt/collection/manager.impl.h b/src/vt/vrt/collection/manager.impl.h
index 11d8b65136..fc366d1c9d 100644
--- a/src/vt/vrt/collection/manager.impl.h
+++ b/src/vt/vrt/collection/manager.impl.h
@@ -1009,7 +1009,7 @@ messaging::PendingSend CollectionManager::broadcastMsgImpl(
 
 template <typename MsgT, typename ColT>
 CollectionManager::IsColMsgType<MsgT> CollectionManager::broadcastMsgWithHan(
-  CollectionProxyWrapType<ColT> const& proxy, MsgT* msg, HandlerType const& h,
+  CollectionProxyWrapType<ColT> const& proxy, MsgT* msg, HandlerType const h,
   bool inst
 ) {
   using IdxT = typename ColT::IndexType;
@@ -1018,7 +1018,7 @@ CollectionManager::IsColMsgType<MsgT> CollectionManager::broadcastMsgWithHan(
 
 template <typename MsgT, typename ColT>
 CollectionManager::IsNotColMsgType<MsgT> CollectionManager::broadcastMsgWithHan(
-  CollectionProxyWrapType<ColT> const& proxy, MsgT* msg, HandlerType const& h,
+  CollectionProxyWrapType<ColT> const& proxy, MsgT* msg, HandlerType const h,
   bool inst
 ) {
   return broadcastNormalMsg<MsgT, ColT>(proxy, msg, h, inst);
@@ -1027,7 +1027,7 @@ CollectionManager::IsNotColMsgType<MsgT> CollectionManager::broadcastMsgWithHan(
 template <typename MsgT, typename ColT>
 messaging::PendingSend CollectionManager::broadcastNormalMsg(
   CollectionProxyWrapType<ColT> const& proxy, MsgT* msg,
-  HandlerType const& handler, bool instrument
+  HandlerType const handler, bool instrument
 ) {
   auto wrap_msg = makeMessage<ColMsgWrap<ColT, MsgT>>(*msg);
   return broadcastMsgUntypedHandler<ColMsgWrap<ColT, MsgT>, ColT>(
@@ -1038,7 +1038,7 @@ messaging::PendingSend CollectionManager::broadcastNormalMsg(
 template <typename MsgT, typename ColT, typename IdxT>
 messaging::PendingSend CollectionManager::broadcastMsgUntypedHandler(
   CollectionProxyWrapType<ColT, IdxT> const& toProxy, MsgT* raw_msg,
-  HandlerType const& handler, bool instrument
+  HandlerType const handler, bool instrument
 ) {
   auto const idx = makeVrtDispatch<MsgT,ColT>();
   auto const col_proxy = toProxy.getProxy();
@@ -1263,7 +1263,7 @@ messaging::PendingSend CollectionManager::reduceMsgExpr(
 template <typename MsgT, typename ColT>
 CollectionManager::IsNotColMsgType<MsgT> CollectionManager::sendMsgWithHan(
   VirtualElmProxyType<ColT> const& proxy, MsgT* msg,
-  HandlerType const& handler
+  HandlerType const handler
 ) {
   return sendNormalMsg<MsgT, ColT>(proxy, msg, handler);
 }
@@ -1271,7 +1271,7 @@ CollectionManager::IsNotColMsgType<MsgT> CollectionManager::sendMsgWithHan(
 template <typename MsgT, typename ColT>
 CollectionManager::IsColMsgType<MsgT> CollectionManager::sendMsgWithHan(
   VirtualElmProxyType<ColT> const& proxy, MsgT* msg,
-  HandlerType const& handler
+  HandlerType const handler
 ) {
   using IdxT = typename ColT::IndexType;
   return sendMsgUntypedHandler<MsgT, ColT, IdxT>(proxy, msg, handler);
@@ -1280,7 +1280,7 @@ CollectionManager::IsColMsgType<MsgT> CollectionManager::sendMsgWithHan(
 template <typename MsgT, typename ColT>
 messaging::PendingSend CollectionManager::sendNormalMsg(
   VirtualElmProxyType<ColT> const& proxy, MsgT* msg,
-  HandlerType const& handler
+  HandlerType const handler
 ) {
   auto wrap_msg = makeMessage<ColMsgWrap<ColT, MsgT>>(*msg);
   return sendMsgUntypedHandler<ColMsgWrap<ColT, MsgT>, ColT>(
@@ -1367,7 +1367,7 @@ messaging::PendingSend CollectionManager::sendMsgImpl(
 template <typename MsgT, typename ColT, typename IdxT>
 messaging::PendingSend CollectionManager::sendMsgUntypedHandler(
   VirtualElmProxyType<ColT> const& toProxy, MsgT* raw_msg,
-  HandlerType const& handler, bool imm_context
+  HandlerType const handler, bool imm_context
 ) {
   auto const& col_proxy = toProxy.getCollectionProxy();
   auto const& elm_proxy = toProxy.getElementProxy();
@@ -1448,7 +1448,7 @@ messaging::PendingSend CollectionManager::sendMsgUntypedHandler(
 template <typename ColT, typename IndexT>
 bool CollectionManager::insertCollectionElement(
   VirtualPtrType<ColT, IndexT> vc, IndexT const& idx, IndexT const& max_idx,
-  HandlerType const& map_han, VirtualProxyType const& proxy,
+  HandlerType const map_han, VirtualProxyType const& proxy,
   bool const is_static, NodeType const& home_node, bool const& is_migrated_in,
   NodeType const& migrated_from
 ) {
@@ -1569,7 +1569,7 @@ template <typename ColT>
 CollectionManager::CollectionProxyWrapType<ColT>
 CollectionManager::constructCollectiveMap(
   typename ColT::IndexType range, DistribConstructFn<ColT> user_construct_fn,
-  HandlerType const& map_han, TagType const& tag
+  HandlerType const map_han, TagType const& tag
 ) {
   using IndexT         = typename ColT::IndexType;
   using TypedProxyType = CollectionProxyWrapType<ColT>;
@@ -1854,7 +1854,7 @@ InsertToken<ColT> CollectionManager::constructInsert(
 
 template <typename ColT>
 InsertToken<ColT> CollectionManager::constructInsertMap(
-  typename ColT::IndexType range, HandlerType const& map_han, TagType const& tag
+  typename ColT::IndexType range, HandlerType const map_han, TagType const& tag
 ) {
   using IndexT         = typename ColT::IndexType;
 
@@ -2063,7 +2063,7 @@ CollectionManager::construct(
 template <typename ColT, typename... Args>
 CollectionManager::CollectionProxyWrapType<ColT, typename ColT::IndexType>
 CollectionManager::constructMap(
-  typename ColT::IndexType range, HandlerType const& map_handler,
+  typename ColT::IndexType range, HandlerType const map_handler,
   Args&&... args
 ) {
   using IndexT = typename ColT::IndexType;
@@ -2111,7 +2111,7 @@ CollectionManager::constructMap(
 }
 
 inline void CollectionManager::insertCollectionInfo(
-  VirtualProxyType const& proxy, HandlerType const& map_han,
+  VirtualProxyType const& proxy, HandlerType const map_han,
   EpochType const& insert_epoch
 ) {
   UniversalIndexHolder<>::insertMap(proxy,map_han,insert_epoch);
@@ -2713,7 +2713,7 @@ template <typename ColT, typename IndexT>
 MigrateStatus CollectionManager::migrateIn(
   VirtualProxyType const& proxy, IndexT const& idx, NodeType const& from,
   VirtualPtrType<ColT, IndexT> vrt_elm_ptr, IndexT const& max,
-  HandlerType const& map_han
+  HandlerType const map_han
 ) {
   vt_debug_print(
     vrt_coll, node,
diff --git a/src/vt/vrt/collection/messages/system_create.h b/src/vt/vrt/collection/messages/system_create.h
index 46284288a0..2fc91f5683 100644
--- a/src/vt/vrt/collection/messages/system_create.h
+++ b/src/vt/vrt/collection/messages/system_create.h
@@ -72,7 +72,7 @@ struct CollectionCreateMsg : ::vt::Message {
 
   CollectionCreateMsg() = default;
   CollectionCreateMsg(
-    HandlerType const& in_han, ArgsTuple&& in_tup
+    HandlerType const in_han, ArgsTuple&& in_tup
   ) : ::vt::Message(), tup(std::forward<ArgsTuple>(in_tup)), map(in_han)
   { }
 
diff --git a/src/vt/vrt/collection/messages/user.h b/src/vt/vrt/collection/messages/user.h
index 27553d6682..17d07c1bf9 100644
--- a/src/vt/vrt/collection/messages/user.h
+++ b/src/vt/vrt/collection/messages/user.h
@@ -87,7 +87,7 @@ struct CollectionMessage : RoutedMessageType<BaseMsgT, ColT> {
     : is_wrap_(true)
   { }
 
-  void setVrtHandler(HandlerType const& in_handler);
+  void setVrtHandler(HandlerType const in_handler);
   HandlerType getVrtHandler() const;
 
   // The variable `to_proxy_' manages the intended target of the
diff --git a/src/vt/vrt/collection/messages/user.impl.h b/src/vt/vrt/collection/messages/user.impl.h
index 31a8401e07..57f756067c 100644
--- a/src/vt/vrt/collection/messages/user.impl.h
+++ b/src/vt/vrt/collection/messages/user.impl.h
@@ -54,7 +54,7 @@ namespace vt { namespace vrt { namespace collection {
 
 template <typename ColT, typename BaseMsgT>
 void CollectionMessage<ColT, BaseMsgT>::setVrtHandler(
-  HandlerType const& in_handler
+  HandlerType const in_handler
 ) {
   vt_sub_handler_ = in_handler;
 }
diff --git a/src/vt/vrt/collection/migrate/manager_migrate_attorney.h b/src/vt/vrt/collection/migrate/manager_migrate_attorney.h
index 9fdd4cc37c..7852d9eb61 100644
--- a/src/vt/vrt/collection/migrate/manager_migrate_attorney.h
+++ b/src/vt/vrt/collection/migrate/manager_migrate_attorney.h
@@ -79,7 +79,7 @@ struct CollectionElmAttorney {
 
   static MigrateStatus migrateIn(
     VirtualProxyType const& proxy, IndexT const& idx, NodeType const& from,
-    VirtualPtrType vc_elm, IndexT const& range, HandlerType const& map_han
+    VirtualPtrType vc_elm, IndexT const& range, HandlerType const map_han
   );
 };
 
diff --git a/src/vt/vrt/collection/migrate/manager_migrate_attorney.impl.h b/src/vt/vrt/collection/migrate/manager_migrate_attorney.impl.h
index 739d943acc..84c2b55a6c 100644
--- a/src/vt/vrt/collection/migrate/manager_migrate_attorney.impl.h
+++ b/src/vt/vrt/collection/migrate/manager_migrate_attorney.impl.h
@@ -74,7 +74,7 @@ template <typename ColT, typename IndexT>
 template <typename ColT, typename IndexT>
 /*static*/ MigrateStatus CollectionElmAttorney<ColT, IndexT>::migrateIn(
   VirtualProxyType const& proxy, IndexT const& idx, NodeType const& from,
-  VirtualPtrType vc_elm, IndexT const& range, HandlerType const& map_han
+  VirtualPtrType vc_elm, IndexT const& range, HandlerType const map_han
 ) {
   return theCollection()->migrateIn<ColT,IndexT>(
     proxy, idx, from, std::move(vc_elm), range, map_han
diff --git a/src/vt/vrt/collection/migrate/migrate_msg.h b/src/vt/vrt/collection/migrate/migrate_msg.h
index 61bca4e31d..31db2db092 100644
--- a/src/vt/vrt/collection/migrate/migrate_msg.h
+++ b/src/vt/vrt/collection/migrate/migrate_msg.h
@@ -60,7 +60,7 @@ struct MigrateMsg final : ::vt::Message {
   MigrateMsg() = default;
   MigrateMsg(
     VrtElmProxy<ColT, IndexT> const& in_elm_proxy, NodeType const& in_from,
-    NodeType const& in_to, HandlerType const& in_map_fn, IndexT const& in_range,
+    NodeType const& in_to, HandlerType const in_map_fn, IndexT const& in_range,
     ColT* in_elm
   ) : elm_proxy_(in_elm_proxy), from_(in_from), to_(in_to), map_fn_(in_map_fn),
       range_(in_range), elm_(in_elm)
diff --git a/src/vt/vrt/context/context_vrtmanager.h b/src/vt/vrt/context/context_vrtmanager.h
index d4d3e65ae6..80a2f9c690 100644
--- a/src/vt/vrt/context/context_vrtmanager.h
+++ b/src/vt/vrt/context/context_vrtmanager.h
@@ -124,12 +124,12 @@ struct VirtualContextManager
 
   void setupMappedVirutalContext(
     VirtualProxyType const& proxy, SeedType const& seed, CoreType const& core,
-    HandlerType const& map_handle
+    HandlerType const map_handle
   );
 
   template <typename VrtContextT, typename... Args>
   VirtualProxyType makeVirtualMapComm(
-    SeedType const& seed, HandlerType const& map_handle, Args&& ... args
+    SeedType const& seed, HandlerType const map_handle, Args&& ... args
   );
 
   template <typename VrtContextT, typename... Args>
diff --git a/src/vt/vrt/context/context_vrtmanager.impl.h b/src/vt/vrt/context/context_vrtmanager.impl.h
index e79131a563..1784a4aca6 100644
--- a/src/vt/vrt/context/context_vrtmanager.impl.h
+++ b/src/vt/vrt/context/context_vrtmanager.impl.h
@@ -144,7 +144,7 @@ messaging::PendingSend VirtualContextManager::sendSerialMsg(
   if (theContext()->getWorker() == worker_id_comm_thread) {
     NodeType const& home_node = VirtualProxyBuilder::getVirtualNode(toProxy);
     // register the user's handler
-    HandlerType const& han = auto_registry::makeAutoHandlerVC<VcT,MsgT,f>();
+    HandlerType const han = auto_registry::makeAutoHandlerVC<VcT,MsgT,f>();
     // save the user's handler in the message
     msg->setVrtHandler(han);
     msg->setProxy(toProxy);
@@ -239,7 +239,7 @@ VirtualProxyType VirtualContextManager::makeVirtualRemote(
 
 inline void VirtualContextManager::setupMappedVirutalContext(
   VirtualProxyType const& proxy, SeedType const& seed, CoreType const& core,
-  HandlerType const& map_handle
+  HandlerType const map_handle
 ) {
   auto vrt_info = getVirtualInfoByProxy(proxy);
   vrt_info->setSeed(seed);
@@ -249,7 +249,7 @@ inline void VirtualContextManager::setupMappedVirutalContext(
 
 template <typename VrtContextT, typename... Args>
 VirtualProxyType VirtualContextManager::makeVirtualMapComm(
-  SeedType const& seed, HandlerType const& map_handle, Args&& ... args
+  SeedType const& seed, HandlerType const map_handle, Args&& ... args
 ) {
   auto const& proxy = makeVirtual<VrtContextT, Args...>(
     std::forward<Args>(args)...
diff --git a/src/vt/vrt/context/context_vrtmessage.h b/src/vt/vrt/context/context_vrtmessage.h
index 9f1ad04217..9dd3a4d1eb 100644
--- a/src/vt/vrt/context/context_vrtmessage.h
+++ b/src/vt/vrt/context/context_vrtmessage.h
@@ -71,7 +71,7 @@ struct VirtualMessage : RoutedMessageType<vt::Message>
 
   // The variable `vc_sub_handler_' manages the intended user handler the
   // VirtualMessage should trigger
-  void setVrtHandler(HandlerType const& in_handler) {
+  void setVrtHandler(HandlerType const in_handler) {
     vt_sub_handler_ = in_handler;
   }
   HandlerType getVrtHandler() const {
diff --git a/tests/unit/mapping/test_mapping_registry.cc b/tests/unit/mapping/test_mapping_registry.cc
index 69c3af57ac..81bd986313 100644
--- a/tests/unit/mapping/test_mapping_registry.cc
+++ b/tests/unit/mapping/test_mapping_registry.cc
@@ -58,7 +58,7 @@ namespace vt { namespace tests { namespace unit {
 struct TestMsg : vt::ShortMessage {
   bool is_block = false;
   HandlerType han;
-  TestMsg(HandlerType const& in_han) : ShortMessage(), han(in_han) { }
+  TestMsg(HandlerType const in_han) : ShortMessage(), han(in_han) { }
 };
 
 struct TestMappingRegistry : TestParallelHarness {