Index: clang-tools-extra/trunk/change-namespace/ChangeNamespace.cpp
===================================================================
--- clang-tools-extra/trunk/change-namespace/ChangeNamespace.cpp
+++ clang-tools-extra/trunk/change-namespace/ChangeNamespace.cpp
@@ -282,6 +282,10 @@
           isNestedDeclContext(DeclCtx, D->getDeclContext()));
 }
 
+AST_MATCHER(EnumDecl, isScoped) {
+    return Node.isScoped();
+}
+
 } // anonymous namespace
 
 ChangeNamespaceTool::ChangeNamespaceTool(
@@ -454,6 +458,17 @@
                                  to(GlobalVarMatcher.bind("var_decl")))
                          .bind("var_ref"),
                      this);
+
+  // Handle unscoped enum constant.
+  auto UnscopedEnumMatcher = enumConstantDecl(hasParent(enumDecl(
+      hasParent(namespaceDecl()),
+      unless(anyOf(isScoped(), IsInMovedNs, hasAncestor(cxxRecordDecl()),
+                   hasAncestor(namespaceDecl(isAnonymous())))))));
+  Finder->addMatcher(
+      declRefExpr(IsInMovedNs, hasAncestor(decl().bind("dc")),
+                  to(UnscopedEnumMatcher.bind("enum_const_decl")))
+          .bind("enum_const_ref"),
+      this);
 }
 
 void ChangeNamespaceTool::run(
@@ -518,6 +533,21 @@
     assert(Context && "Empty decl context.");
     fixDeclRefExpr(Result, Context->getDeclContext(),
                    llvm::cast<NamedDecl>(Var), VarRef);
+  } else if (const auto *EnumConstRef =
+                 Result.Nodes.getNodeAs<DeclRefExpr>("enum_const_ref")) {
+    // Do not rename the reference if it is already scoped by the EnumDecl name.
+    if (EnumConstRef->hasQualifier() &&
+        EnumConstRef->getQualifier()->getAsType()->isEnumeralType())
+      return;
+    const auto *EnumConstDecl =
+        Result.Nodes.getNodeAs<EnumConstantDecl>("enum_const_decl");
+    assert(EnumConstDecl);
+    const auto *Context = Result.Nodes.getNodeAs<Decl>("dc");
+    assert(Context && "Empty decl context.");
+    // FIXME: this would qualify "ns::VALUE" as "ns::EnumValue::VALUE". Fix it
+    // if it turns out to be an issue.
+    fixDeclRefExpr(Result, Context->getDeclContext(),
+                   llvm::cast<NamedDecl>(EnumConstDecl), EnumConstRef);
   } else if (const auto *FuncRef =
                  Result.Nodes.getNodeAs<DeclRefExpr>("func_ref")) {
     // If this reference has been processed as a function call, we do not
Index: clang-tools-extra/trunk/unittests/change-namespace/ChangeNamespaceTests.cpp
===================================================================
--- clang-tools-extra/trunk/unittests/change-namespace/ChangeNamespaceTests.cpp
+++ clang-tools-extra/trunk/unittests/change-namespace/ChangeNamespaceTests.cpp
@@ -1774,6 +1774,207 @@
   EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
 }
 
+TEST_F(ChangeNamespaceTest, SimpleMoveEnum) {
+  std::string Code = "namespace na {\n"
+                     "namespace nb {\n"
+                     "enum class X { X1, X2 };\n"
+                     "enum Y { Y1, Y2 };\n"
+                     "} // namespace nb\n"
+                     "} // namespace na\n";
+  std::string Expected = "\n\nnamespace x {\n"
+                         "namespace y {\n"
+                         "enum class X { X1, X2 };\n"
+                         "enum Y { Y1, Y2 };\n"
+                         "} // namespace y\n"
+                         "} // namespace x\n";
+
+  EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
+}
+
+TEST_F(ChangeNamespaceTest, ReferencesToEnums) {
+  std::string Code = "enum Glob { G1, G2 };\n"
+                     "namespace na {\n"
+                     "enum class X { X1 };\n"
+                     "enum Y { Y1, Y2 };\n"
+                     "namespace nb {\n"
+                     "void f() {\n"
+                     "  Glob g1 = Glob::G1;\n"
+                     "  Glob g2 = G2;\n"
+                     "  X x1 = X::X1;\n"
+                     "  Y y1 = Y::Y1;\n"
+                     "  Y y2 = Y2;\n"
+                     "}\n"
+                     "} // namespace nb\n"
+                     "} // namespace na\n";
+  std::string Expected = "enum Glob { G1, G2 };\n"
+                         "namespace na {\n"
+                         "enum class X { X1 };\n"
+                         "enum Y { Y1, Y2 };\n"
+                         "\n"
+                         "} // namespace na\n"
+                         "namespace x {\n"
+                         "namespace y {\n"
+                         "void f() {\n"
+                         "  Glob g1 = Glob::G1;\n"
+                         "  Glob g2 = G2;\n"
+                         "  ::na::X x1 = ::na::X::X1;\n"
+                         "  ::na::Y y1 = ::na::Y::Y1;\n"
+                         "  ::na::Y y2 = ::na::Y::Y2;\n"
+                         "}\n"
+                         "} // namespace y\n"
+                         "} // namespace x\n";
+
+  EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
+}
+
+TEST_F(ChangeNamespaceTest, NoRedundantEnumUpdate) {
+  std::string Code = "namespace ns {\n"
+                     "enum class X { X1 };\n"
+                     "enum Y { Y1, Y2 };\n"
+                     "} // namespace ns\n"
+                     "namespace na {\n"
+                     "namespace nb {\n"
+                     "void f() {\n"
+                     "  ns::X x1 = ns::X::X1;\n"
+                     "  ns::Y y1 = ns::Y::Y1;\n"
+                     "  ns::Y y2 = ns::Y2;\n"
+                     "}\n"
+                     "} // namespace nb\n"
+                     "} // namespace na\n";
+  std::string Expected = "namespace ns {\n"
+                         "enum class X { X1 };\n"
+                         "enum Y { Y1, Y2 };\n"
+                         "} // namespace ns\n"
+                         "\n"
+                         "namespace x {\n"
+                         "namespace y {\n"
+                         "void f() {\n"
+                         "  ns::X x1 = ns::X::X1;\n"
+                         "  ns::Y y1 = ns::Y::Y1;\n"
+                         // FIXME: this is redundant
+                         "  ns::Y y2 = ::ns::Y::Y2;\n"
+                         "}\n"
+                         "} // namespace y\n"
+                         "} // namespace x\n";
+  ;
+
+  EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
+}
+
+TEST_F(ChangeNamespaceTest, EnumsAndUsingShadows) {
+  std::string Code = "namespace ns {\n"
+                     "enum class X { X1 };\n"
+                     "enum Y { Y1, Y2, Y3 };\n"
+                     "} // namespace ns\n"
+                     "using ns::X;\n"
+                     "using ns::Y;\n"
+                     "using ns::Y::Y2;\n"
+                     "using ns::Y::Y3;\n"
+                     "namespace na {\n"
+                     "namespace nb {\n"
+                     "void f() {\n"
+                     "  X x1 = X::X1;\n"
+                     "  Y y1 = Y::Y1;\n"
+                     "  Y y2 = Y2;\n"
+                     "  Y y3 = Y3;\n"
+                     "}\n"
+                     "} // namespace nb\n"
+                     "} // namespace na\n";
+  std::string Expected = "namespace ns {\n"
+                         "enum class X { X1 };\n"
+                         "enum Y { Y1, Y2, Y3 };\n"
+                         "} // namespace ns\n"
+                         "using ns::X;\n"
+                         "using ns::Y;\n"
+                         "using ns::Y::Y2;\n"
+                         "using ns::Y::Y3;\n"
+                         "\n"
+                         "namespace x {\n"
+                         "namespace y {\n"
+                         "void f() {\n"
+                         "  X x1 = X::X1;\n"
+                         "  Y y1 = Y::Y1;\n"
+                         "  Y y2 = Y2;\n"
+                         "  Y y3 = Y3;\n"
+                         "}\n"
+                         "} // namespace y\n"
+                         "} // namespace x\n";
+
+  EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
+}
+
+TEST_F(ChangeNamespaceTest, EnumsAndAliases) {
+  std::string Code = "namespace ns {\n"
+                     "enum class X { X1 };\n"
+                     "enum Y { Y1, Y2, Y3 };\n"
+                     "} // namespace ns\n"
+                     "typedef ns::X TX;\n"
+                     "typedef ns::Y TY;\n"
+                     "using UX = ns::X;\n"
+                     "using UY = ns::Y;\n"
+                     "namespace na {\n"
+                     "namespace nb {\n"
+                     "void f() {\n"
+                     "  ns::X x1 = ns::X::X1;\n"
+                     "  TX tx1 = TX::X1;\n"
+                     "  UX ux1 = UX::X1;\n"
+                     "  ns::Y y1 = ns::Y::Y1;\n"
+                     "  TY ty1 = TY::Y1;\n"
+                     "  UY uy1 = UY::Y1;\n"
+                     "}\n"
+                     "} // namespace nb\n"
+                     "} // namespace na\n";
+  std::string Expected = "namespace ns {\n"
+                         "enum class X { X1 };\n"
+                         "enum Y { Y1, Y2, Y3 };\n"
+                         "} // namespace ns\n"
+                         "typedef ns::X TX;\n"
+                         "typedef ns::Y TY;\n"
+                         "using UX = ns::X;\n"
+                         "using UY = ns::Y;\n"
+                         "\n"
+                         "namespace x {\n"
+                         "namespace y {\n"
+                         "void f() {\n"
+                         "  ns::X x1 = ns::X::X1;\n"
+                         "  TX tx1 = TX::X1;\n"
+                         "  UX ux1 = UX::X1;\n"
+                         "  ns::Y y1 = ns::Y::Y1;\n"
+                         "  TY ty1 = TY::Y1;\n"
+                         "  UY uy1 = UY::Y1;\n"
+                         "}\n"
+                         "} // namespace y\n"
+                         "} // namespace x\n";
+
+  EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
+}
+
+TEST_F(ChangeNamespaceTest, EnumInClass) {
+  std::string Code = "namespace na {\n"
+                     "struct X { enum E { E1 }; };\n"
+                     "namespace nb {\n"
+                     "void f() {\n"
+                     "  X::E e = X::E1;\n"
+                     "  X::E ee = X::E::E1;\n"
+                     "}\n"
+                     "} // namespace nb\n"
+                     "} // namespace na\n";
+  std::string Expected = "namespace na {\n"
+                         "struct X { enum E { E1 }; };\n"
+                         "\n"
+                         "} // namespace na\n"
+                         "namespace x {\n"
+                         "namespace y {\n"
+                         "void f() {\n"
+                         "  ::na::X::E e = ::na::X::E1;\n"
+                         "  ::na::X::E ee = ::na::X::E::E1;\n"
+                         "}\n"
+                         "} // namespace y\n"
+                         "} // namespace x\n";
+
+  EXPECT_EQ(format(Expected), runChangeNamespaceOnCode(Code));
+}
+
 } // anonymous namespace
 } // namespace change_namespace
 } // namespace clang