Handle UsingDecl and UsingShadowDecl in DeclContextPrinter

This commit fixes a crash that occurs when -print-decl-contexts AST consumer
tries to print an unhandled declaration.

rdar://19467234

Differential Revision: https://reviews.llvm.org/D26964

llvm-svn: 290881

clang/lib/Frontend/ASTConsumers.cpp

@@ -485,6 +485,14 @@ void DeclContextPrinter::PrintDeclContext(const DeclContext* DC,
       Out << "\n";
       break;
     }
+    case Decl::Using: {
+      Out << "<using> " << *cast<UsingDecl>(I) << "\n";
+      break;
+    }
+    case Decl::UsingShadow: {
+      Out << "<using shadow> " << *cast<UsingShadowDecl>(I) << "\n";
+      break;
+    }
     default:
       Out << "DeclKind: " << DK << '"' << I << "\"\n";
       llvm_unreachable("decl unhandled");

clang/test/Coverage/cxx-language-features.inc

@@ -33,3 +33,11 @@ struct FriendlyStruct {
 };
 
 struct FriendedStruct { };
+
+// Using declaration
+namespace provider {
+  void foo();
+}
+namespace user {
+  using provider::foo;
+}