Add dump info for VarDecl

A VarDecl can either be a declaration, a definition, or a tentative
definition. This dumps that information because it turned out to be
useful for a discussion trying to understand a difference in behavior
between C and C++.

Author: AaronBallman

clang/lib/AST/TextNodeDumper.cpp

@@ -2461,13 +2461,27 @@ void TextNodeDumper::VisitVarDecl(const VarDecl *D) {
       break;
     case VarDecl::ParenListInit:
       OS << " parenlistinit";
+      break;
     }
   }
   if (D->needsDestruction(D->getASTContext()))
     OS << " destroyed";
   if (D->isParameterPack())
     OS << " pack";
 
+  VarDecl::DefinitionKind K = D->isThisDeclarationADefinition();
+  switch (K) {
+  case VarDecl::DefinitionKind::DeclarationOnly:
+    OS << " declaration";
+    break;
+  case VarDecl::DefinitionKind::Definition:
+    OS << " definition";
+    break;
+  case VarDecl::DefinitionKind::TentativeDefinition:
+    OS << " tentative definition";
+    break;
+  }
+
   if (const auto *Instance = D->getTemplateInstantiationPattern()) {
     OS << " instantiated_from";
     dumpPointer(Instance);