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

llvm-svn: 344140

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index f05c8a39823..1667536c567 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -13,7 +13,6 @@
 #include "ToolChains/Clang.h"
 #include "clang/Basic/ObjCRuntime.h"
 #include "clang/Basic/Sanitizers.h"
-#include "clang/Basic/VirtualFileSystem.h"
 #include "clang/Config/config.h"
 #include "clang/Driver/Action.h"
 #include "clang/Driver/Driver.h"
@@ -39,6 +38,7 @@
 #include "llvm/Support/TargetParser.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/VersionTuple.h"
+#include "llvm/Support/VirtualFileSystem.h"
 #include <cassert>
 #include <cstddef>
 #include <cstring>
@@ -99,7 +99,9 @@ void ToolChain::setTripleEnvironment(llvm::Triple::EnvironmentType Env) {
 
 ToolChain::~ToolChain() = default;
 
-vfs::FileSystem &ToolChain::getVFS() const { return getDriver().getVFS(); }
+llvm::vfs::FileSystem &ToolChain::getVFS() const {
+  return getDriver().getVFS();
+}
 
 bool ToolChain::useIntegratedAs() const {
   return Args.hasFlag(options::OPT_fintegrated_as,