Update Clang for rebase to r212749.

This also fixes a small issue with arm_neon.h not being generated always.

Includes a cherry-pick of:
r213450 - fixes mac-specific header issue
r213126 - removes a default -Bsymbolic on Android

Change-Id: I2a790a0f5d3b2aab11de596fc3a74e7cbc99081d
diff --git a/unittests/Basic/VirtualFileSystemTest.cpp b/unittests/Basic/VirtualFileSystemTest.cpp
index 40d2f16..e7d361e 100644
--- a/unittests/Basic/VirtualFileSystemTest.cpp
+++ b/unittests/Basic/VirtualFileSystemTest.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/Basic/VirtualFileSystem.h"
+#include "llvm/Support/Errc.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/SourceMgr.h"
@@ -35,20 +36,63 @@
     std::map<std::string, vfs::Status>::iterator I =
         FilesAndDirs.find(Path.str());
     if (I == FilesAndDirs.end())
-      return error_code(errc::no_such_file_or_directory, posix_category());
+      return make_error_code(llvm::errc::no_such_file_or_directory);
     return I->second;
   }
-  error_code openFileForRead(const Twine &Path,
-                             std::unique_ptr<vfs::File> &Result) {
+  std::error_code openFileForRead(const Twine &Path,
+                                  std::unique_ptr<vfs::File> &Result) {
     llvm_unreachable("unimplemented");
   }
-  error_code getBufferForFile(const Twine &Name,
-                              std::unique_ptr<MemoryBuffer> &Result,
-                              int64_t FileSize = -1,
-                              bool RequiresNullTerminator = true) {
+  std::error_code getBufferForFile(const Twine &Name,
+                                   std::unique_ptr<MemoryBuffer> &Result,
+                                   int64_t FileSize = -1,
+                                   bool RequiresNullTerminator = true) {
     llvm_unreachable("unimplemented");
   }
 
+  struct DirIterImpl : public clang::vfs::detail::DirIterImpl {
+    std::map<std::string, vfs::Status> &FilesAndDirs;
+    std::map<std::string, vfs::Status>::iterator I;
+    std::string Path;
+    bool isInPath(StringRef S) {
+      if (Path.size() < S.size() && S.find(Path) == 0) {
+        auto LastSep = S.find_last_of('/');
+        if (LastSep == Path.size() || LastSep == Path.size()-1)
+          return true;
+      }
+      return false;
+    }
+    DirIterImpl(std::map<std::string, vfs::Status> &FilesAndDirs,
+                const Twine &_Path)
+        : FilesAndDirs(FilesAndDirs), I(FilesAndDirs.begin()),
+          Path(_Path.str()) {
+      for ( ; I != FilesAndDirs.end(); ++I) {
+        if (isInPath(I->first)) {
+          CurrentEntry = I->second;
+          break;
+        }
+      }
+    }
+    std::error_code increment() override {
+      ++I;
+      for ( ; I != FilesAndDirs.end(); ++I) {
+        if (isInPath(I->first)) {
+          CurrentEntry = I->second;
+          break;
+        }
+      }
+      if (I == FilesAndDirs.end())
+        CurrentEntry = vfs::Status();
+      return std::error_code();
+    }
+  };
+
+  vfs::directory_iterator dir_begin(const Twine &Dir,
+                                    std::error_code &EC) override {
+    return vfs::directory_iterator(
+        std::make_shared<DirIterImpl>(FilesAndDirs, Dir));
+  }
+
   void addEntry(StringRef Path, const vfs::Status &Status) {
     FilesAndDirs[Path] = Status;
   }
@@ -75,11 +119,11 @@
 
 TEST(VirtualFileSystemTest, StatusQueries) {
   IntrusiveRefCntPtr<DummyFileSystem> D(new DummyFileSystem());
-  ErrorOr<vfs::Status> Status((error_code()));
+  ErrorOr<vfs::Status> Status((std::error_code()));
 
   D->addRegularFile("/foo");
   Status = D->status("/foo");
-  ASSERT_EQ(errc::success, Status.getError());
+  ASSERT_FALSE(Status.getError());
   EXPECT_TRUE(Status->isStatusKnown());
   EXPECT_FALSE(Status->isDirectory());
   EXPECT_TRUE(Status->isRegularFile());
@@ -89,7 +133,7 @@
 
   D->addDirectory("/bar");
   Status = D->status("/bar");
-  ASSERT_EQ(errc::success, Status.getError());
+  ASSERT_FALSE(Status.getError());
   EXPECT_TRUE(Status->isStatusKnown());
   EXPECT_TRUE(Status->isDirectory());
   EXPECT_FALSE(Status->isRegularFile());
@@ -99,7 +143,7 @@
 
   D->addSymlink("/baz");
   Status = D->status("/baz");
-  ASSERT_EQ(errc::success, Status.getError());
+  ASSERT_FALSE(Status.getError());
   EXPECT_TRUE(Status->isStatusKnown());
   EXPECT_FALSE(Status->isDirectory());
   EXPECT_FALSE(Status->isRegularFile());
@@ -109,13 +153,13 @@
 
   EXPECT_TRUE(Status->equivalent(*Status));
   ErrorOr<vfs::Status> Status2 = D->status("/foo");
-  ASSERT_EQ(errc::success, Status2.getError());
+  ASSERT_FALSE(Status2.getError());
   EXPECT_FALSE(Status->equivalent(*Status2));
 }
 
 TEST(VirtualFileSystemTest, BaseOnlyOverlay) {
   IntrusiveRefCntPtr<DummyFileSystem> D(new DummyFileSystem());
-  ErrorOr<vfs::Status> Status((error_code()));
+  ErrorOr<vfs::Status> Status((std::error_code()));
   EXPECT_FALSE(Status = D->status("/foo"));
 
   IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(new vfs::OverlayFileSystem(D));
@@ -123,11 +167,11 @@
 
   D->addRegularFile("/foo");
   Status = D->status("/foo");
-  EXPECT_EQ(errc::success, Status.getError());
+  EXPECT_FALSE(Status.getError());
 
-  ErrorOr<vfs::Status> Status2((error_code()));
+  ErrorOr<vfs::Status> Status2((std::error_code()));
   Status2 = O->status("/foo");
-  EXPECT_EQ(errc::success, Status2.getError());
+  EXPECT_FALSE(Status2.getError());
   EXPECT_TRUE(Status->equivalent(*Status2));
 }
 
@@ -140,25 +184,26 @@
   O->pushOverlay(Middle);
   O->pushOverlay(Top);
 
-  ErrorOr<vfs::Status> Status1((error_code())), Status2((error_code())),
-      Status3((error_code())), StatusB((error_code())), StatusM((error_code())),
-      StatusT((error_code()));
+  ErrorOr<vfs::Status> Status1((std::error_code())),
+      Status2((std::error_code())), Status3((std::error_code())),
+      StatusB((std::error_code())), StatusM((std::error_code())),
+      StatusT((std::error_code()));
 
   Base->addRegularFile("/foo");
   StatusB = Base->status("/foo");
-  ASSERT_EQ(errc::success, StatusB.getError());
+  ASSERT_FALSE(StatusB.getError());
   Status1 = O->status("/foo");
-  ASSERT_EQ(errc::success, Status1.getError());
+  ASSERT_FALSE(Status1.getError());
   Middle->addRegularFile("/foo");
   StatusM = Middle->status("/foo");
-  ASSERT_EQ(errc::success, StatusM.getError());
+  ASSERT_FALSE(StatusM.getError());
   Status2 = O->status("/foo");
-  ASSERT_EQ(errc::success, Status2.getError());
+  ASSERT_FALSE(Status2.getError());
   Top->addRegularFile("/foo");
   StatusT = Top->status("/foo");
-  ASSERT_EQ(errc::success, StatusT.getError());
+  ASSERT_FALSE(StatusT.getError());
   Status3 = O->status("/foo");
-  ASSERT_EQ(errc::success, Status3.getError());
+  ASSERT_FALSE(Status3.getError());
 
   EXPECT_TRUE(Status1->equivalent(*StatusB));
   EXPECT_TRUE(Status2->equivalent(*StatusM));
@@ -181,15 +226,15 @@
 
   // non-merged paths should be the same
   ErrorOr<vfs::Status> Status1 = Lower->status("/lower-only");
-  ASSERT_EQ(errc::success, Status1.getError());
+  ASSERT_FALSE(Status1.getError());
   ErrorOr<vfs::Status> Status2 = O->status("/lower-only");
-  ASSERT_EQ(errc::success, Status2.getError());
+  ASSERT_FALSE(Status2.getError());
   EXPECT_TRUE(Status1->equivalent(*Status2));
 
   Status1 = Upper->status("/upper-only");
-  ASSERT_EQ(errc::success, Status1.getError());
+  ASSERT_FALSE(Status1.getError());
   Status2 = O->status("/upper-only");
-  ASSERT_EQ(errc::success, Status2.getError());
+  ASSERT_FALSE(Status2.getError());
   EXPECT_TRUE(Status1->equivalent(*Status2));
 }
 
@@ -201,24 +246,281 @@
       new vfs::OverlayFileSystem(Lower));
   O->pushOverlay(Upper);
 
-  ErrorOr<vfs::Status> Status((error_code()));
+  ErrorOr<vfs::Status> Status((std::error_code()));
   Lower->addDirectory("/both", sys::fs::owner_read);
   Upper->addDirectory("/both", sys::fs::owner_all | sys::fs::group_read);
   Status = O->status("/both");
-  ASSERT_EQ(errc::success, Status.getError());
+  ASSERT_FALSE(Status.getError());
   EXPECT_EQ(0740, Status->getPermissions());
 
   // permissions (as usual) are not recursively applied
   Lower->addRegularFile("/both/foo", sys::fs::owner_read);
   Upper->addRegularFile("/both/bar", sys::fs::owner_write);
   Status = O->status("/both/foo");
-  ASSERT_EQ(errc::success, Status.getError());
+  ASSERT_FALSE( Status.getError());
   EXPECT_EQ(0400, Status->getPermissions());
   Status = O->status("/both/bar");
-  ASSERT_EQ(errc::success, Status.getError());
+  ASSERT_FALSE(Status.getError());
   EXPECT_EQ(0200, Status->getPermissions());
 }
 
+namespace {
+struct ScopedDir {
+  SmallString<128> Path;
+  ScopedDir(const Twine &Name, bool Unique=false) {
+    std::error_code EC;
+    if (Unique) {
+      EC =  llvm::sys::fs::createUniqueDirectory(Name, Path);
+    } else {
+      Path = Name.str();
+      EC = llvm::sys::fs::create_directory(Twine(Path));
+    }
+    if (EC)
+      Path = "";
+    EXPECT_FALSE(EC);
+  }
+  ~ScopedDir() {
+    if (Path != "")
+      EXPECT_FALSE(llvm::sys::fs::remove(Path.str()));
+  }
+  operator StringRef() { return Path.str(); }
+};
+}
+
+TEST(VirtualFileSystemTest, BasicRealFSIteration) {
+  ScopedDir TestDirectory("virtual-file-system-test", /*Unique*/true);
+  IntrusiveRefCntPtr<vfs::FileSystem> FS = vfs::getRealFileSystem();
+
+  std::error_code EC;
+  vfs::directory_iterator I = FS->dir_begin(Twine(TestDirectory), EC);
+  ASSERT_FALSE(EC);
+  EXPECT_EQ(vfs::directory_iterator(), I); // empty directory is empty
+
+  ScopedDir _a(TestDirectory+"/a");
+  ScopedDir _ab(TestDirectory+"/a/b");
+  ScopedDir _c(TestDirectory+"/c");
+  ScopedDir _cd(TestDirectory+"/c/d");
+
+  I = FS->dir_begin(Twine(TestDirectory), EC);
+  ASSERT_FALSE(EC);
+  ASSERT_NE(vfs::directory_iterator(), I);
+  // Check either a or c, since we can't rely on the iteration order.
+  EXPECT_TRUE(I->getName().endswith("a") || I->getName().endswith("c"));
+  I.increment(EC);
+  ASSERT_FALSE(EC);
+  ASSERT_NE(vfs::directory_iterator(), I);
+  EXPECT_TRUE(I->getName().endswith("a") || I->getName().endswith("c"));
+  I.increment(EC);
+  EXPECT_EQ(vfs::directory_iterator(), I);
+}
+
+TEST(VirtualFileSystemTest, BasicRealFSRecursiveIteration) {
+  ScopedDir TestDirectory("virtual-file-system-test", /*Unique*/true);
+  IntrusiveRefCntPtr<vfs::FileSystem> FS = vfs::getRealFileSystem();
+
+  std::error_code EC;
+  auto I = vfs::recursive_directory_iterator(*FS, Twine(TestDirectory), EC);
+  ASSERT_FALSE(EC);
+  EXPECT_EQ(vfs::recursive_directory_iterator(), I); // empty directory is empty
+
+  ScopedDir _a(TestDirectory+"/a");
+  ScopedDir _ab(TestDirectory+"/a/b");
+  ScopedDir _c(TestDirectory+"/c");
+  ScopedDir _cd(TestDirectory+"/c/d");
+
+  I = vfs::recursive_directory_iterator(*FS, Twine(TestDirectory), EC);
+  ASSERT_FALSE(EC);
+  ASSERT_NE(vfs::recursive_directory_iterator(), I);
+
+
+  std::vector<std::string> Contents;
+  for (auto E = vfs::recursive_directory_iterator(); !EC && I != E;
+       I.increment(EC)) {
+    Contents.push_back(I->getName());
+  }
+
+  // Check contents, which may be in any order
+  EXPECT_EQ(4U, Contents.size());
+  int Counts[4] = { 0, 0, 0, 0 };
+  for (const std::string &Name : Contents) {
+    ASSERT_FALSE(Name.empty());
+    int Index = Name[Name.size()-1] - 'a';
+    ASSERT_TRUE(Index >= 0 && Index < 4);
+    Counts[Index]++;
+  }
+  EXPECT_EQ(1, Counts[0]); // a
+  EXPECT_EQ(1, Counts[1]); // b
+  EXPECT_EQ(1, Counts[2]); // c
+  EXPECT_EQ(1, Counts[3]); // d
+}
+
+template <typename T, size_t N>
+std::vector<StringRef> makeStringRefVector(const T (&Arr)[N]) {
+  std::vector<StringRef> Vec;
+  for (size_t i = 0; i != N; ++i)
+    Vec.push_back(Arr[i]);
+  return Vec;
+}
+
+template <typename DirIter>
+static void checkContents(DirIter I, ArrayRef<StringRef> Expected) {
+  std::error_code EC;
+  auto ExpectedIter = Expected.begin(), ExpectedEnd = Expected.end();
+  for (DirIter E;
+       !EC && I != E && ExpectedIter != ExpectedEnd;
+       I.increment(EC), ++ExpectedIter)
+    EXPECT_EQ(*ExpectedIter, I->getName());
+
+  EXPECT_EQ(ExpectedEnd, ExpectedIter);
+  EXPECT_EQ(DirIter(), I);
+}
+
+TEST(VirtualFileSystemTest, OverlayIteration) {
+  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
+  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
+  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
+      new vfs::OverlayFileSystem(Lower));
+  O->pushOverlay(Upper);
+
+  std::error_code EC;
+  checkContents(O->dir_begin("/", EC), ArrayRef<StringRef>());
+
+  Lower->addRegularFile("/file1");
+  checkContents(O->dir_begin("/", EC), ArrayRef<StringRef>("/file1"));
+
+  Upper->addRegularFile("/file2");
+  {
+    const char *Contents[] = {"/file2", "/file1"};
+    checkContents(O->dir_begin("/", EC), makeStringRefVector(Contents));
+  }
+
+  Lower->addDirectory("/dir1");
+  Lower->addRegularFile("/dir1/foo");
+  Upper->addDirectory("/dir2");
+  Upper->addRegularFile("/dir2/foo");
+  checkContents(O->dir_begin("/dir2", EC), ArrayRef<StringRef>("/dir2/foo"));
+  {
+    const char *Contents[] = {"/dir2", "/file2", "/dir1", "/file1"};
+    checkContents(O->dir_begin("/", EC), makeStringRefVector(Contents));
+  }
+}
+
+TEST(VirtualFileSystemTest, OverlayRecursiveIteration) {
+  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
+  IntrusiveRefCntPtr<DummyFileSystem> Middle(new DummyFileSystem());
+  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
+  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
+      new vfs::OverlayFileSystem(Lower));
+  O->pushOverlay(Middle);
+  O->pushOverlay(Upper);
+
+  std::error_code EC;
+  checkContents(vfs::recursive_directory_iterator(*O, "/", EC),
+                ArrayRef<StringRef>());
+
+  Lower->addRegularFile("/file1");
+  checkContents(vfs::recursive_directory_iterator(*O, "/", EC),
+                ArrayRef<StringRef>("/file1"));
+
+  Upper->addDirectory("/dir");
+  Upper->addRegularFile("/dir/file2");
+  {
+    const char *Contents[] = {"/dir", "/dir/file2", "/file1"};
+    checkContents(vfs::recursive_directory_iterator(*O, "/", EC),
+                  makeStringRefVector(Contents));
+  }
+
+  Lower->addDirectory("/dir1");
+  Lower->addRegularFile("/dir1/foo");
+  Lower->addDirectory("/dir1/a");
+  Lower->addRegularFile("/dir1/a/b");
+  Middle->addDirectory("/a");
+  Middle->addDirectory("/a/b");
+  Middle->addDirectory("/a/b/c");
+  Middle->addRegularFile("/a/b/c/d");
+  Middle->addRegularFile("/hiddenByUp");
+  Upper->addDirectory("/dir2");
+  Upper->addRegularFile("/dir2/foo");
+  Upper->addRegularFile("/hiddenByUp");
+  checkContents(vfs::recursive_directory_iterator(*O, "/dir2", EC),
+                ArrayRef<StringRef>("/dir2/foo"));
+  {
+    const char *Contents[] = { "/dir", "/dir/file2", "/dir2", "/dir2/foo",
+        "/hiddenByUp", "/a", "/a/b", "/a/b/c", "/a/b/c/d", "/dir1", "/dir1/a",
+        "/dir1/a/b", "/dir1/foo", "/file1" };
+    checkContents(vfs::recursive_directory_iterator(*O, "/", EC),
+                  makeStringRefVector(Contents));
+  }
+}
+
+TEST(VirtualFileSystemTest, ThreeLevelIteration) {
+  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
+  IntrusiveRefCntPtr<DummyFileSystem> Middle(new DummyFileSystem());
+  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
+  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
+      new vfs::OverlayFileSystem(Lower));
+  O->pushOverlay(Middle);
+  O->pushOverlay(Upper);
+
+  std::error_code EC;
+  checkContents(O->dir_begin("/", EC), ArrayRef<StringRef>());
+
+  Middle->addRegularFile("/file2");
+  checkContents(O->dir_begin("/", EC), ArrayRef<StringRef>("/file2"));
+
+  Lower->addRegularFile("/file1");
+  Upper->addRegularFile("/file3");
+  {
+    const char *Contents[] = {"/file3", "/file2", "/file1"};
+    checkContents(O->dir_begin("/", EC), makeStringRefVector(Contents));
+  }
+}
+
+TEST(VirtualFileSystemTest, HiddenInIteration) {
+  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
+  IntrusiveRefCntPtr<DummyFileSystem> Middle(new DummyFileSystem());
+  IntrusiveRefCntPtr<DummyFileSystem> Upper(new DummyFileSystem());
+  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
+      new vfs::OverlayFileSystem(Lower));
+  O->pushOverlay(Middle);
+  O->pushOverlay(Upper);
+
+  std::error_code EC;
+  Lower->addRegularFile("/onlyInLow", sys::fs::owner_read);
+  Lower->addRegularFile("/hiddenByMid", sys::fs::owner_read);
+  Lower->addRegularFile("/hiddenByUp", sys::fs::owner_read);
+  Middle->addRegularFile("/onlyInMid", sys::fs::owner_write);
+  Middle->addRegularFile("/hiddenByMid", sys::fs::owner_write);
+  Middle->addRegularFile("/hiddenByUp", sys::fs::owner_write);
+  Upper->addRegularFile("/onlyInUp", sys::fs::owner_all);
+  Upper->addRegularFile("/hiddenByUp", sys::fs::owner_all);
+  {
+    const char *Contents[] = {"/hiddenByUp", "/onlyInUp", "/hiddenByMid",
+                              "/onlyInMid", "/onlyInLow"};
+    checkContents(O->dir_begin("/", EC), makeStringRefVector(Contents));
+  }
+
+  // Make sure we get the top-most entry
+  {
+    std::error_code EC;
+    vfs::directory_iterator I = O->dir_begin("/", EC), E;
+    for ( ; !EC && I != E; I.increment(EC))
+      if (I->getName() == "/hiddenByUp")
+        break;
+    ASSERT_NE(E, I);
+    EXPECT_EQ(sys::fs::owner_all, I->getPermissions());
+  }
+  {
+    std::error_code EC;
+    vfs::directory_iterator I = O->dir_begin("/", EC), E;
+    for ( ; !EC && I != E; I.increment(EC))
+      if (I->getName() == "/hiddenByMid")
+        break;
+    ASSERT_NE(E, I);
+    EXPECT_EQ(sys::fs::owner_write, I->getPermissions());
+  }
+}
+
 // NOTE: in the tests below, we use '//root/' as our root directory, since it is
 // a legal *absolute* path on Windows as well as *nix.
 class VFSFromYAMLTest : public ::testing::Test {
@@ -253,11 +555,11 @@
 TEST_F(VFSFromYAMLTest, BasicVFSFromYAML) {
   IntrusiveRefCntPtr<vfs::FileSystem> FS;
   FS = getFromYAMLString("");
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString("[]");
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString("'string'");
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   EXPECT_EQ(3, NumDiagnostics);
 }
 
@@ -284,7 +586,7 @@
                         "]\n"
                         "}",
                         Lower);
-  ASSERT_TRUE(FS.getPtr() != NULL);
+  ASSERT_TRUE(FS.get() != nullptr);
 
   IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
       new vfs::OverlayFileSystem(Lower));
@@ -292,7 +594,7 @@
 
   // file
   ErrorOr<vfs::Status> S = O->status("//root/file1");
-  ASSERT_EQ(errc::success, S.getError());
+  ASSERT_FALSE(S.getError());
   EXPECT_EQ("//root/foo/bar/a", S->getName());
 
   ErrorOr<vfs::Status> SLower = O->status("//root/foo/bar/a");
@@ -301,12 +603,13 @@
 
   // directory
   S = O->status("//root/");
-  ASSERT_EQ(errc::success, S.getError());
+  ASSERT_FALSE(S.getError());
   EXPECT_TRUE(S->isDirectory());
   EXPECT_TRUE(S->equivalent(*O->status("//root/"))); // non-volatile UniqueID
 
   // broken mapping
-  EXPECT_EQ(errc::no_such_file_or_directory, O->status("//root/file2").getError());
+  EXPECT_EQ(O->status("//root/file2").getError(),
+            llvm::errc::no_such_file_or_directory);
   EXPECT_EQ(0, NumDiagnostics);
 }
 
@@ -327,17 +630,17 @@
                         "              ]\n"
                         "}]}",
                         Lower);
-  ASSERT_TRUE(FS.getPtr() != NULL);
+  ASSERT_TRUE(FS.get() != nullptr);
 
   IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
       new vfs::OverlayFileSystem(Lower));
   O->pushOverlay(FS);
 
   ErrorOr<vfs::Status> S = O->status("//root/XX");
-  ASSERT_EQ(errc::success, S.getError());
+  ASSERT_FALSE(S.getError());
 
   ErrorOr<vfs::Status> SS = O->status("//root/xx");
-  ASSERT_EQ(errc::success, SS.getError());
+  ASSERT_FALSE(SS.getError());
   EXPECT_TRUE(S->equivalent(*SS));
   SS = O->status("//root/xX");
   EXPECT_TRUE(S->equivalent(*SS));
@@ -363,18 +666,18 @@
                         "              ]\n"
                         "}]}",
                         Lower);
-  ASSERT_TRUE(FS.getPtr() != NULL);
+  ASSERT_TRUE(FS.get() != nullptr);
 
   IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
       new vfs::OverlayFileSystem(Lower));
   O->pushOverlay(FS);
 
   ErrorOr<vfs::Status> SS = O->status("//root/xx");
-  EXPECT_EQ(errc::no_such_file_or_directory, SS.getError());
+  EXPECT_EQ(SS.getError(), llvm::errc::no_such_file_or_directory);
   SS = O->status("//root/xX");
-  EXPECT_EQ(errc::no_such_file_or_directory, SS.getError());
+  EXPECT_EQ(SS.getError(), llvm::errc::no_such_file_or_directory);
   SS = O->status("//root/Xx");
-  EXPECT_EQ(errc::no_such_file_or_directory, SS.getError());
+  EXPECT_EQ(SS.getError(), llvm::errc::no_such_file_or_directory);
   EXPECT_EQ(0, NumDiagnostics);
 }
 
@@ -383,89 +686,89 @@
 
   // invalid YAML at top-level
   IntrusiveRefCntPtr<vfs::FileSystem> FS = getFromYAMLString("{]", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   // invalid YAML in roots
   FS = getFromYAMLString("{ 'roots':[}", Lower);
   // invalid YAML in directory
   FS = getFromYAMLString(
       "{ 'roots':[ { 'name': 'foo', 'type': 'directory', 'contents': [}",
       Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
 
   // invalid configuration
   FS = getFromYAMLString("{ 'knobular': 'true', 'roots':[] }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString("{ 'case-sensitive': 'maybe', 'roots':[] }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
 
   // invalid roots
   FS = getFromYAMLString("{ 'roots':'' }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString("{ 'roots':{} }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
 
   // invalid entries
   FS = getFromYAMLString(
       "{ 'roots':[ { 'type': 'other', 'name': 'me', 'contents': '' }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString("{ 'roots':[ { 'type': 'file', 'name': [], "
                          "'external-contents': 'other' }",
                          Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString(
       "{ 'roots':[ { 'type': 'file', 'name': 'me', 'external-contents': [] }",
       Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString(
       "{ 'roots':[ { 'type': 'file', 'name': 'me', 'external-contents': {} }",
       Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString(
       "{ 'roots':[ { 'type': 'directory', 'name': 'me', 'contents': {} }",
       Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString(
       "{ 'roots':[ { 'type': 'directory', 'name': 'me', 'contents': '' }",
       Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString(
       "{ 'roots':[ { 'thingy': 'directory', 'name': 'me', 'contents': [] }",
       Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
 
   // missing mandatory fields
   FS = getFromYAMLString("{ 'roots':[ { 'type': 'file', 'name': 'me' }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString(
       "{ 'roots':[ { 'type': 'file', 'external-contents': 'other' }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString("{ 'roots':[ { 'name': 'me', 'contents': [] }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
 
   // duplicate keys
   FS = getFromYAMLString("{ 'roots':[], 'roots':[] }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLString(
       "{ 'case-sensitive':'true', 'case-sensitive':'true', 'roots':[] }",
       Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS =
       getFromYAMLString("{ 'roots':[{'name':'me', 'name':'you', 'type':'file', "
                         "'external-contents':'blah' } ] }",
                         Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
 
   // missing version
   FS = getFromYAMLRawString("{ 'roots':[] }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
 
   // bad version number
   FS = getFromYAMLRawString("{ 'version':'foo', 'roots':[] }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLRawString("{ 'version':-1, 'roots':[] }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   FS = getFromYAMLRawString("{ 'version':100000, 'roots':[] }", Lower);
-  EXPECT_EQ(NULL, FS.getPtr());
+  EXPECT_EQ(nullptr, FS.get());
   EXPECT_EQ(24, NumDiagnostics);
 }
 
@@ -487,7 +790,7 @@
       "    'external-contents': '//root/external/file'\n"
       "  }\n"
       "] }", Lower);
-  ASSERT_TRUE(NULL != FS.getPtr());
+  ASSERT_TRUE(nullptr != FS.get());
 
   // default true
   EXPECT_EQ("//root/external/file", FS->status("//root/A")->getName());
@@ -511,7 +814,7 @@
       "    'external-contents': '//root/external/file'\n"
       "  }\n"
       "] }", Lower);
-  ASSERT_TRUE(NULL != FS.getPtr());
+  ASSERT_TRUE(nullptr != FS.get());
 
   // default
   EXPECT_EQ("//root/A", FS->status("//root/A")->getName());
@@ -530,11 +833,11 @@
       "  { 'type': 'file', 'name': '//root/path/to/file',\n"
       "    'external-contents': '//root/other' }]\n"
       "}", Lower);
-  ASSERT_TRUE(NULL != FS.getPtr());
-  EXPECT_EQ(errc::success, FS->status("//root/path/to/file").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/path/to").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/path").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/").getError());
+  ASSERT_TRUE(nullptr != FS.get());
+  EXPECT_FALSE(FS->status("//root/path/to/file").getError());
+  EXPECT_FALSE(FS->status("//root/path/to").getError());
+  EXPECT_FALSE(FS->status("//root/path").getError());
+  EXPECT_FALSE(FS->status("//root/").getError());
 
   // at the start
   FS = getFromYAMLString(
@@ -543,11 +846,11 @@
       "    'contents': [ { 'type': 'file', 'name': 'file',\n"
       "                    'external-contents': '//root/other' }]}]\n"
       "}", Lower);
-  ASSERT_TRUE(NULL != FS.getPtr());
-  EXPECT_EQ(errc::success, FS->status("//root/path/to/file").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/path/to").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/path").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/").getError());
+  ASSERT_TRUE(nullptr != FS.get());
+  EXPECT_FALSE(FS->status("//root/path/to/file").getError());
+  EXPECT_FALSE(FS->status("//root/path/to").getError());
+  EXPECT_FALSE(FS->status("//root/path").getError());
+  EXPECT_FALSE(FS->status("//root/").getError());
 
   // at the end
   FS = getFromYAMLString(
@@ -556,11 +859,11 @@
       "    'contents': [ { 'type': 'file', 'name': 'path/to/file',\n"
       "                    'external-contents': '//root/other' }]}]\n"
       "}", Lower);
-  ASSERT_TRUE(NULL != FS.getPtr());
-  EXPECT_EQ(errc::success, FS->status("//root/path/to/file").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/path/to").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/path").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/").getError());
+  ASSERT_TRUE(nullptr != FS.get());
+  EXPECT_FALSE(FS->status("//root/path/to/file").getError());
+  EXPECT_FALSE(FS->status("//root/path/to").getError());
+  EXPECT_FALSE(FS->status("//root/path").getError());
+  EXPECT_FALSE(FS->status("//root/").getError());
 }
 
 TEST_F(VFSFromYAMLTest, TrailingSlashes) {
@@ -574,9 +877,58 @@
       "    'contents': [ { 'type': 'file', 'name': 'file',\n"
       "                    'external-contents': '//root/other' }]}]\n"
       "}", Lower);
-  ASSERT_TRUE(NULL != FS.getPtr());
-  EXPECT_EQ(errc::success, FS->status("//root/path/to/file").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/path/to").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/path").getError());
-  EXPECT_EQ(errc::success, FS->status("//root/").getError());
+  ASSERT_TRUE(nullptr != FS.get());
+  EXPECT_FALSE(FS->status("//root/path/to/file").getError());
+  EXPECT_FALSE(FS->status("//root/path/to").getError());
+  EXPECT_FALSE(FS->status("//root/path").getError());
+  EXPECT_FALSE(FS->status("//root/").getError());
+}
+
+TEST_F(VFSFromYAMLTest, DirectoryIteration) {
+  IntrusiveRefCntPtr<DummyFileSystem> Lower(new DummyFileSystem());
+  Lower->addDirectory("//root/");
+  Lower->addDirectory("//root/foo");
+  Lower->addDirectory("//root/foo/bar");
+  Lower->addRegularFile("//root/foo/bar/a");
+  Lower->addRegularFile("//root/foo/bar/b");
+  Lower->addRegularFile("//root/file3");
+  IntrusiveRefCntPtr<vfs::FileSystem> FS =
+  getFromYAMLString("{ 'use-external-names': false,\n"
+                    "  'roots': [\n"
+                    "{\n"
+                    "  'type': 'directory',\n"
+                    "  'name': '//root/',\n"
+                    "  'contents': [ {\n"
+                    "                  'type': 'file',\n"
+                    "                  'name': 'file1',\n"
+                    "                  'external-contents': '//root/foo/bar/a'\n"
+                    "                },\n"
+                    "                {\n"
+                    "                  'type': 'file',\n"
+                    "                  'name': 'file2',\n"
+                    "                  'external-contents': '//root/foo/bar/b'\n"
+                    "                }\n"
+                    "              ]\n"
+                    "}\n"
+                    "]\n"
+                    "}",
+                    Lower);
+  ASSERT_TRUE(FS.get() != NULL);
+
+  IntrusiveRefCntPtr<vfs::OverlayFileSystem> O(
+      new vfs::OverlayFileSystem(Lower));
+  O->pushOverlay(FS);
+
+  std::error_code EC;
+  {
+    const char *Contents[] = {"//root/file1", "//root/file2", "//root/file3",
+                              "//root/foo"};
+    checkContents(O->dir_begin("//root/", EC), makeStringRefVector(Contents));
+  }
+
+  {
+    const char *Contents[] = {"//root/foo/bar/a", "//root/foo/bar/b"};
+    checkContents(O->dir_begin("//root/foo/bar", EC),
+                  makeStringRefVector(Contents));
+  }
 }