Fix -Wcovered-switch-default uncovered after r338630

llvm-svn: 338643
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index a88bee3..b31e41d 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -154,11 +154,11 @@
 
 const char *DeclContext::getDeclKindName() const {
   switch (getDeclKind()) {
-  default: llvm_unreachable("Declaration context not in DeclNodes.inc!");
 #define DECL(DERIVED, BASE) case Decl::DERIVED: return #DERIVED;
 #define ABSTRACT_DECL(DECL)
 #include "clang/AST/DeclNodes.inc"
   }
+  llvm_unreachable("Declaration context not in DeclNodes.inc!");
 }
 
 bool Decl::StatisticsEnabled = false;