Fixes errors with FS iterators caused by https://reviews.llvm.org/D44960

Summary:
In https://reviews.llvm.org/D44960, file status check is executed every
time a real file system directory iterator is constructed or
incremented, and emits an error code. This change list fixes the errors
in VirtualFileSystem caused by https://reviews.llvm.org/D44960.

Patch by Yuke Liao (@liaoyuke).

Reviewers: vsk, pcc, zturner, liaoyuke

Reviewed By: vsk

Subscribers: mgrang, cfe-commits

Differential Revision: https://reviews.llvm.org/D45178

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@329223 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Basic/VirtualFileSystem.cpp

@@ -286,24 +286,26 @@ class RealFSDirIter : public clang::vfs::detail::DirIterImpl {
 
 public:
   RealFSDirIter(const Twine &Path, std::error_code &EC) : Iter(Path, EC) {
-    if (!EC && Iter != llvm::sys::fs::directory_iterator()) {
+    if (Iter != llvm::sys::fs::directory_iterator()) {
       llvm::sys::fs::file_status S;
-      EC = llvm::sys::fs::status(Iter->path(), S, true);
+      std::error_code ErrorCode = llvm::sys::fs::status(Iter->path(), S, true);
       CurrentEntry = Status::copyWithNewName(S, Iter->path());
+      if (!EC)
+        EC = ErrorCode;
     }
   }
 
   std::error_code increment() override {
     std::error_code EC;
     Iter.increment(EC);
-    if (EC) {
-      return EC;
-    } else if (Iter == llvm::sys::fs::directory_iterator()) {
+    if (Iter == llvm::sys::fs::directory_iterator()) {
       CurrentEntry = Status();
     } else {
       llvm::sys::fs::file_status S;
-      EC = llvm::sys::fs::status(Iter->path(), S, true);
+      std::error_code ErrorCode = llvm::sys::fs::status(Iter->path(), S, true);
       CurrentEntry = Status::copyWithNewName(S, Iter->path());
+      if (!EC)
+        EC = ErrorCode;
     }
     return EC;
   }

unittests/Basic/VirtualFileSystemTest.cpp

@@ -442,16 +442,17 @@ TEST(VirtualFileSystemTest, BrokenSymlinkRealFSRecursiveIteration) {
   ScopedDir _dd(TestDirectory + "/d/d");
   ScopedDir _ddd(TestDirectory + "/d/d/d");
   ScopedLink _e("no_such_file", TestDirectory + "/e");
-  std::vector<StringRef> Expected = {_b, _bb, _d, _dd, _ddd};
 
-  std::vector<std::string> Contents;
+  std::vector<StringRef> ExpectedBrokenSymlinks = {_a, _ba, _bc, _c, _e};
+  std::vector<StringRef> ExpectedNonBrokenSymlinks = {_b, _bb, _d, _dd, _ddd};
+  std::vector<std::string> VisitedBrokenSymlinks;
+  std::vector<std::string> VisitedNonBrokenSymlinks;
   std::error_code EC;
   for (vfs::recursive_directory_iterator I(*FS, Twine(TestDirectory), EC), E;
        I != E; I.increment(EC)) {
-    // Skip broken symlinks.
     auto EC2 = std::make_error_code(std::errc::no_such_file_or_directory);
     if (EC == EC2) {
-      EC.clear();
+      VisitedBrokenSymlinks.push_back(I->getName());
       continue;
     }
     // For bot debugging.
@@ -467,13 +468,20 @@ TEST(VirtualFileSystemTest, BrokenSymlinkRealFSRecursiveIteration) {
              << "EC message: " << EC2.message() << "\n";
     }
     ASSERT_FALSE(EC);
-    Contents.push_back(I->getName());
+    VisitedNonBrokenSymlinks.push_back(I->getName());
   }
 
-  // Check sorted contents.
-  llvm::sort(Contents.begin(), Contents.end());
-  EXPECT_EQ(Expected.size(), Contents.size());
-  EXPECT_TRUE(std::equal(Contents.begin(), Contents.end(), Expected.begin()));
+  // Check visited file names.
+  std::sort(VisitedBrokenSymlinks.begin(), VisitedBrokenSymlinks.end());
+  std::sort(VisitedNonBrokenSymlinks.begin(), VisitedNonBrokenSymlinks.end());
+  EXPECT_EQ(ExpectedBrokenSymlinks.size(), VisitedBrokenSymlinks.size());
+  EXPECT_TRUE(std::equal(VisitedBrokenSymlinks.begin(),
+                         VisitedBrokenSymlinks.end(),
+                         ExpectedBrokenSymlinks.begin()));
+  EXPECT_EQ(ExpectedNonBrokenSymlinks.size(), VisitedNonBrokenSymlinks.size());
+  EXPECT_TRUE(std::equal(VisitedNonBrokenSymlinks.begin(),
+                         VisitedNonBrokenSymlinks.end(),
+                         ExpectedNonBrokenSymlinks.begin()));
 }
 #endif