[VirtualFileSystem] Support creating directories then adding files inside

Summary:
In https://reviews.llvm.org/D39572 , I added support for specifying
`Type` when invoking `InMemoryFileSystem::addFile()`.

However, I didn't account for the fact that when `Type` is
`directory_file`, we need to construct an `InMemoryDirectory`, not an
`InMemoryFile`, or else clients cannot create files inside that
directory.

This diff fixes the bug and adds a test.

Test Plan: New test added. Ran test with:

  % make -j12 check-clang-tools

Reviewers: bkramer, hokein

Reviewed By: bkramer

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D40140

llvm-svn: 318445

clang/include/clang/Basic/VirtualFileSystem.h

@@ -319,19 +319,23 @@ public:
   explicit InMemoryFileSystem(bool UseNormalizedPaths = true);
   ~InMemoryFileSystem() override;
 
-  /// Add a buffer to the VFS with a path. The VFS owns the buffer.
-  /// If present, User, Group, Type and Perms apply to the newly-created file.
-  /// \return true if the file was successfully added, false if the file already
-  /// exists in the file system with different contents.
+  /// Add a file containing a buffer or a directory to the VFS with a
+  /// path. The VFS owns the buffer.  If present, User, Group, Type
+  /// and Perms apply to the newly-created file or directory.
+  /// \return true if the file or directory was successfully added,
+  /// false if the file or directory already exists in the file system with
+  /// different contents.
   bool addFile(const Twine &Path, time_t ModificationTime,
                std::unique_ptr<llvm::MemoryBuffer> Buffer,
                Optional<uint32_t> User = None, Optional<uint32_t> Group = None,
                Optional<llvm::sys::fs::file_type> Type = None,
                Optional<llvm::sys::fs::perms> Perms = None);
   /// Add a buffer to the VFS with a path. The VFS does not own the buffer.
-  /// If present, User, Group, Type and Perms apply to the newly-created file.
-  /// \return true if the file was successfully added, false if the file already
-  /// exists in the file system with different contents.
+  /// If present, User, Group, Type and Perms apply to the newly-created file
+  /// or directory.
+  /// \return true if the file or directory was successfully added,
+  /// false if the file or directory already exists in the file system with
+  /// different contents.
   bool addFileNoOwn(const Twine &Path, time_t ModificationTime,
                     llvm::MemoryBuffer *Buffer,
                     Optional<uint32_t> User = None,

clang/lib/Basic/VirtualFileSystem.cpp

@@ -527,13 +527,19 @@ bool InMemoryFileSystem::addFile(const Twine &P, time_t ModificationTime,
     ++I;
     if (!Node) {
       if (I == E) {
-        // End of the path, create a new file.
+        // End of the path, create a new file or directory.
         Status Stat(P.str(), getNextVirtualUniqueID(),
                     llvm::sys::toTimePoint(ModificationTime), ResolvedUser,
                     ResolvedGroup, Buffer->getBufferSize(), ResolvedType,
                     ResolvedPerms);
-        Dir->addChild(Name, llvm::make_unique<detail::InMemoryFile>(
-                                std::move(Stat), std::move(Buffer)));
+        std::unique_ptr<detail::InMemoryNode> Child;
+        if (ResolvedType == sys::fs::file_type::directory_file) {
+          Child.reset(new detail::InMemoryDirectory(std::move(Stat)));
+        } else {
+          Child.reset(new detail::InMemoryFile(std::move(Stat),
+                                               std::move(Buffer)));
+        }
+        Dir->addChild(Name, std::move(Child));
         return true;
       }
 

clang/unittests/Basic/VirtualFileSystemTest.cpp

@@ -829,6 +829,19 @@ TEST_F(InMemoryFileSystemTest, AddFileWithPerms) {
             Stat->getPermissions());
 }
 
+TEST_F(InMemoryFileSystemTest, AddDirectoryThenAddChild) {
+  FS.addFile("/a", 0, MemoryBuffer::getMemBuffer(""), /*User=*/None,
+             /*Group=*/None, sys::fs::file_type::directory_file);
+  FS.addFile("/a/b", 0, MemoryBuffer::getMemBuffer("abc"), /*User=*/None,
+             /*Group=*/None, sys::fs::file_type::regular_file);
+  auto Stat = FS.status("/a");
+  ASSERT_FALSE(Stat.getError()) << Stat.getError() << "\n" << FS.toString();
+  ASSERT_TRUE(Stat->isDirectory());
+  Stat = FS.status("/a/b");
+  ASSERT_FALSE(Stat.getError()) << Stat.getError() << "\n" << FS.toString();
+  ASSERT_TRUE(Stat->isRegularFile());
+}
+
 // 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 {