#2268: avoid maybe_uninitialized warning

Author: cz4rs

src/vt/collective/reduce/reduce.impl.h

@@ -165,7 +165,8 @@ detail::ReduceStamp Reduce::reduceImmediate(
     envelopeSetGroup(msg->env, std::get<detail::StrongGroup>(scope_.get()).get());
   }
 
-  auto cur_id = id == detail::ReduceStamp{} ? generateNextID() : id;
+  auto default_stamp = detail::ReduceStamp{};
+  auto cur_id = id == default_stamp ? generateNextID() : id;
 
   auto const han = auto_registry::makeAutoHandler<MsgT,f>();
   msg->combine_handler_ = han;

src/vt/vrt/collection/manager.impl.h

@@ -921,7 +921,8 @@ messaging::PendingSend CollectionManager::reduceMsgExpr(
   vtAssert(group_ready, "Must be ready");
 
   auto cur_stamp = stamp;
-  if (cur_stamp == ReduceStamp{}) {
+  auto default_stamp = ReduceStamp{};
+  if (cur_stamp == default_stamp) {
     cur_stamp = proxy(idx).tryGetLocalPtr()->getNextStamp();
   }