[VFS] Transition clang-format to use an in-memory FS.

Apart from being cleaner this also means that clang-format no longer has
access to the host file system. This isn't necessary because clang-format
never reads includes :)

Includes minor tweaks and bugfixes found in the VFS implementation while
running clang-format tests.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@249385 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/include/clang/Basic/VirtualFileSystem.h b/include/clang/Basic/VirtualFileSystem.h
index 52bcce2cd1..36a14b794c 100644
--- a/include/clang/Basic/VirtualFileSystem.h
+++ b/include/clang/Basic/VirtualFileSystem.h
@@ -274,8 +274,12 @@ class InMemoryFileSystem : public FileSystem {
 public:
   InMemoryFileSystem();
   ~InMemoryFileSystem() override;
+  /// Add a buffer to the VFS with a path. The VFS owns the buffer.
   void addFile(const Twine &Path, time_t ModificationTime,
                std::unique_ptr<llvm::MemoryBuffer> Buffer);
+  /// Add a buffer to the VFS with a path. The VFS does not own the buffer.
+  void addFileNoOwn(const Twine &Path, time_t ModificationTime,
+                    llvm::MemoryBuffer *Buffer);
   StringRef toString() const;
 
   llvm::ErrorOr<Status> status(const Twine &Path) override;