A slightly cleaner way to express the logic here

Author: tbkka

include/swift/Demangling/TypeDecoder.h

@@ -693,16 +693,16 @@ class TypeDecoder {
 
         // If the tuple element is labeled, add its label to 'labels'.
         unsigned typeChildIndex = 0;
-        if (element->getChild(0)->getKind() == NodeKind::VariadicMarker) {
-          return BuiltType(); // Reject a variadic tuple mangling
+        if (element->getChild(typeChildIndex)->getKind() == NodeKind::VariadicMarker) {
+          return BuiltType();
         }
-        if (element->getChild(0)->getKind() == NodeKind::TupleElementName) {
+        if (element->getChild(typeChildIndex)->getKind() == NodeKind::TupleElementName) {
           // Add spaces to terminate all the previous labels if this
           // is the first we've seen.
           if (labels.empty()) labels.append(elements.size(), ' ');
 
           // Add the label and its terminator.
-          labels += element->getChild(0)->getText();
+          labels += element->getChild(typeChildIndex)->getText();
           labels += ' ';
           typeChildIndex++;