Lift VFS from clang to llvm (NFC)

This patch moves the virtual file system form clang to llvm so it can be
used by more projects.

Concretely the patch:
 - Moves VirtualFileSystem.{h|cpp} from clang/Basic to llvm/Support.
 - Moves the corresponding unit test from clang to llvm.
 - Moves the vfs namespace from clang::vfs to llvm::vfs.
 - Formats the lines affected by this change, mostly this is the result of
   the added llvm namespace.

RFC on the mailing list:
http://lists.llvm.org/pipermail/llvm-dev/2018-October/126657.html

Differential revision: https://reviews.llvm.org/D52783

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@344140 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 11 deletions

diff --git a/include/clang/Frontend/PrecompiledPreamble.h b/include/clang/Frontend/PrecompiledPreamble.h
index e2855fbdf2..6c79895ce1 100644
--- a/include/clang/Frontend/PrecompiledPreamble.h
+++ b/include/clang/Frontend/PrecompiledPreamble.h
@@ -26,13 +26,12 @@
 
 namespace llvm {
 class MemoryBuffer;
-}
-
-namespace clang {
 namespace vfs {
 class FileSystem;
 }
+} // namespace llvm
 
+namespace clang {
 class CompilerInstance;
 class CompilerInvocation;
 class DeclGroupRef;
@@ -80,7 +79,8 @@ public:
   static llvm::ErrorOr<PrecompiledPreamble>
   Build(const CompilerInvocation &Invocation,
         const llvm::MemoryBuffer *MainFileBuffer, PreambleBounds Bounds,
-        DiagnosticsEngine &Diagnostics, IntrusiveRefCntPtr<vfs::FileSystem> VFS,
+        DiagnosticsEngine &Diagnostics,
+        IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
         std::shared_ptr<PCHContainerOperations> PCHContainerOps,
         bool StoreInMemory, PreambleCallbacks &Callbacks);
 
@@ -99,7 +99,7 @@ public:
   /// MainFileBuffer) of the main file.
   bool CanReuse(const CompilerInvocation &Invocation,
                 const llvm::MemoryBuffer *MainFileBuffer, PreambleBounds Bounds,
-                vfs::FileSystem *VFS) const;
+                llvm::vfs::FileSystem *VFS) const;
 
   /// Changes options inside \p CI to use PCH from this preamble. Also remaps
   /// main file to \p MainFileBuffer and updates \p VFS to ensure the preamble
@@ -110,14 +110,14 @@ public:
   /// responsible for making sure the PrecompiledPreamble instance outlives the
   /// compiler run and the AST that will be using the PCH.
   void AddImplicitPreamble(CompilerInvocation &CI,
-                           IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
+                           IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS,
                            llvm::MemoryBuffer *MainFileBuffer) const;
 
   /// Configure \p CI to use this preamble.
   /// Like AddImplicitPreamble, but doesn't assume CanReuse() is true.
   /// If this preamble does not match the file, it may parse differently.
   void OverridePreamble(CompilerInvocation &CI,
-                        IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
+                        IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS,
                         llvm::MemoryBuffer *MainFileBuffer) const;
 
 private:
@@ -233,15 +233,16 @@ private:
   /// Helper function to set up PCH for the preamble into \p CI and \p VFS to
   /// with the specified \p Bounds.
   void configurePreamble(PreambleBounds Bounds, CompilerInvocation &CI,
-                         IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
+                         IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS,
                          llvm::MemoryBuffer *MainFileBuffer) const;
 
   /// Sets up the PreprocessorOptions and changes VFS, so that PCH stored in \p
   /// Storage is accessible to clang. This method is an implementation detail of
   /// AddImplicitPreamble.
-  static void setupPreambleStorage(const PCHStorage &Storage,
-                                   PreprocessorOptions &PreprocessorOpts,
-                                   IntrusiveRefCntPtr<vfs::FileSystem> &VFS);
+  static void
+  setupPreambleStorage(const PCHStorage &Storage,
+                       PreprocessorOptions &PreprocessorOpts,
+                       IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS);
 
   /// Manages the memory buffer or temporary file that stores the PCH.
   PCHStorage Storage;