[Tooling] Add an overload of runToolOnCodeWithArgs that takes VFS

[ioeric]

Summary

... to support purely VFS-based tools.

[bkramer]

lg

include/clang/Tooling/Tooling.h

 bool runToolOnCodeWithArgs(
     FrontendAction *ToolAction, const Twine &Code,
     const std::vector<std::string> &Args, const Twine &FileName = "input.cc",
     const Twine &ToolName = "clang-tool",
     std::shared_ptr<PCHContainerOperations> PCHContainerOps =
         std::make_shared<PCHContainerOperations>(),
     const FileContentMappings &VirtualMappedFiles = FileContentMappings());
 
+// Similar to the overload except this takes a VFS.
+bool runToolOnCodeWithArgs(
+    FrontendAction *ToolAction, const Twine &Code,
+    llvm::IntrusiveRefCntPtr<vfs::FileSystem> VFS,
+    const std::vector<std::string> &Args, const Twine &FileName = "input.cc",
+    const Twine &ToolName = "clang-tool",
+    std::shared_ptr<PCHContainerOperations> PCHContainerOps =
+        std::make_shared<PCHContainerOperations>());
+
 /// Builds an AST for 'Code'.
 ///
 /// \param Code C++ code.
 /// \param FileName The file name which 'Code' will be mapped as.
 /// \param PCHContainerOps The PCHContainerOperations for loading and creating
 /// clang modules.
 ///
 /// \return The resulting AST or null if an error occurred.

lib/Tooling/Tooling.cpp

getSyntaxOnlyToolArgs(const Twine &ToolName,
   return Args;
 }
 
 namespace clang {
 namespace tooling {
 
 bool runToolOnCodeWithArgs(
     FrontendAction *ToolAction, const Twine &Code,
+    llvm::IntrusiveRefCntPtr<vfs::FileSystem> VFS,
     const std::vector<std::string> &Args, const Twine &FileName,
     const Twine &ToolName,
-    std::shared_ptr<PCHContainerOperations> PCHContainerOps,
-    const FileContentMappings &VirtualMappedFiles) {
+    std::shared_ptr<PCHContainerOperations> PCHContainerOps) {
   SmallString<16> FileNameStorage;
   StringRef FileNameRef = FileName.toNullTerminatedStringRef(FileNameStorage);
-  llvm::IntrusiveRefCntPtr<vfs::OverlayFileSystem> OverlayFileSystem(
-      new vfs::OverlayFileSystem(vfs::getRealFileSystem()));
-  llvm::IntrusiveRefCntPtr<vfs::InMemoryFileSystem> InMemoryFileSystem(
-      new vfs::InMemoryFileSystem);
-  OverlayFileSystem->pushOverlay(InMemoryFileSystem);
+
   llvm::IntrusiveRefCntPtr<FileManager> Files(
-      new FileManager(FileSystemOptions(), OverlayFileSystem));
+      new FileManager(FileSystemOptions(), VFS));
   ArgumentsAdjuster Adjuster = getClangStripDependencyFileAdjuster();
   ToolInvocation Invocation(
       getSyntaxOnlyToolArgs(ToolName, Adjuster(Args, FileNameRef), FileNameRef),
       ToolAction, Files.get(),
       std::move(PCHContainerOps));
+  return Invocation.run();
+}
+
+bool runToolOnCodeWithArgs(
+    FrontendAction *ToolAction, const Twine &Code,
+    const std::vector<std::string> &Args, const Twine &FileName,
+    const Twine &ToolName,
+    std::shared_ptr<PCHContainerOperations> PCHContainerOps,
+    const FileContentMappings &VirtualMappedFiles) {
+  llvm::IntrusiveRefCntPtr<vfs::OverlayFileSystem> OverlayFileSystem(
+      new vfs::OverlayFileSystem(vfs::getRealFileSystem()));
+  llvm::IntrusiveRefCntPtr<vfs::InMemoryFileSystem> InMemoryFileSystem(
+      new vfs::InMemoryFileSystem);
+  OverlayFileSystem->pushOverlay(InMemoryFileSystem);
 
   SmallString<1024> CodeStorage;
-  InMemoryFileSystem->addFile(FileNameRef, 0,
+  InMemoryFileSystem->addFile(FileName, 0,
                               llvm::MemoryBuffer::getMemBuffer(
                                   Code.toNullTerminatedStringRef(CodeStorage)));
 
   for (auto &FilenameWithContent : VirtualMappedFiles) {
     InMemoryFileSystem->addFile(
         FilenameWithContent.first, 0,
         llvm::MemoryBuffer::getMemBuffer(FilenameWithContent.second));
   }
 
-  return Invocation.run();
+  return runToolOnCodeWithArgs(ToolAction, Code, OverlayFileSystem, Args,
+                               FileName, ToolName);
 }
 
 std::string getAbsolutePath(StringRef File) {
   StringRef RelativePath(File);
   // FIXME: Should '.\\' be accepted on Win32?
   if (RelativePath.startswith("./")) {
     RelativePath = RelativePath.substr(strlen("./"));
   }