[CodeCompletion] Hide underscored code completion results in argument completion

Author: ahoppen

lib/IDE/ArgumentCompletion.cpp

@@ -115,6 +115,9 @@ void ArgumentTypeCheckCompletionCallback::sawSolutionImpl(const Solution &S) {
   auto *CalleeLocator = S.getCalleeLocator(CallLocator);
 
   auto Info = getSelectedOverloadInfo(S, CalleeLocator);
+  if (Info.Value && Info.Value->shouldHideFromEditor()) {
+    return;
+  }
 
   // Find the parameter the completion was bound to (if any), as well as which
   // parameters are already bound (so we don't suggest them even when the args