Index: clang-tools-extra/clangd/index/dex/Dex.cpp
===================================================================
--- clang-tools-extra/clangd/index/dex/Dex.cpp
+++ clang-tools-extra/clangd/index/dex/Dex.cpp
@@ -144,8 +144,10 @@
     if (It != InvertedIndex.end())
       TrigramIterators.push_back(create(It->second));
   }
-  if (!TrigramIterators.empty())
+  if (TrigramIterators.size() > 1)
     TopLevelChildren.push_back(createAnd(move(TrigramIterators)));
+  else if (TrigramIterators.size() == 1)
+    TopLevelChildren.push_back(move(TrigramIterators.front()));
 
   // Generate scope tokens for search query.
   std::vector<std::unique_ptr<Iterator>> ScopeIterators;
@@ -155,8 +157,10 @@
       ScopeIterators.push_back(create(It->second));
   }
   // Add OR iterator for scopes if there are any Scope Iterators.
-  if (!ScopeIterators.empty())
+  if (ScopeIterators.size() > 1)
     TopLevelChildren.push_back(createOr(move(ScopeIterators)));
+  else if (ScopeIterators.size() == 1)
+    TopLevelChildren.push_back(move(ScopeIterators.front()));
 
   // Add proximity paths boosting.
   auto BoostingIterators = createFileProximityIterators(