[Tooling] Remove unused function setRestoreWorkingDir

[kazu]

Summary

The last use was removed by:

commit 146ec74a8382dc820809d0a2bf4b918d0b5e6603
Author: Jan Svoboda <[e-mail]>
Date:   Fri Sep 10 10:24:16 2021 +0200

Once I remove the function, RestoreCWD is always true, so this patch
removes the variable and propagates the constant.

[jansvoboda11]

LGTM

clang/include/clang/Tooling/Tooling.h

public:
   /// \returns 0 on success; 1 if any error occurred; 2 if there is no error but
   /// some files are skipped due to missing compile commands.
   int run(ToolAction *Action);
 
   /// Create an AST for each file specified in the command line and
   /// append them to ASTs.
   int buildASTs(std::vector<std::unique_ptr<ASTUnit>> &ASTs);
 
-  /// Sets whether working directory should be restored after calling run(). By
-  /// default, working directory is restored. However, it could be useful to
-  /// turn this off when running on multiple threads to avoid the raciness.
-  void setRestoreWorkingDir(bool RestoreCWD);
-
   /// Sets whether an error message should be printed out if an action fails. By
   /// default, if an action fails, a message is printed out to stderr.
   void setPrintErrorMessage(bool PrintErrorMessage);
 
   /// Returns the file manager used in the tool.
   ///
   /// The file manager is shared between all translation units.
   FileManager &getFiles() { return *Files; }
private:
   std::vector<std::pair<StringRef, StringRef>> MappedFileContents;
 
   llvm::StringSet<> SeenWorkingDirectories;
 
   ArgumentsAdjuster ArgsAdjuster;
 
   DiagnosticConsumer *DiagConsumer = nullptr;
 
-  bool RestoreCWD = true;
   bool PrintErrorMessage = true;
 };
 
 template <typename T>
 std::unique_ptr<FrontendActionFactory> newFrontendActionFactory() {
   class SimpleFrontendActionFactory : public FrontendActionFactory {
   public:
     std::unique_ptr<FrontendAction> create() override {

clang/lib/Tooling/Tooling.cpp

if (!AbsPath) {
                    << llvm::toString(AbsPath.takeError()) << "\n";
       continue;
     }
     AbsolutePaths.push_back(std::move(*AbsPath));
   }
 
   // Remember the working directory in case we need to restore it.
   std::string InitialWorkingDir;
-  if (RestoreCWD) {
-    if (auto CWD = OverlayFileSystem->getCurrentWorkingDirectory()) {
-      InitialWorkingDir = std::move(*CWD);
-    } else {
-      llvm::errs() << "Could not get working directory: "
-                   << CWD.getError().message() << "\n";
-    }
-  }
 
   for (llvm::StringRef File : AbsolutePaths) {
     // Currently implementations of CompilationDatabase::getCompileCommands can
     // change the state of the file system (e.g.  prepare generated headers), so
     // this method needs to run right before we invoke the tool, as the next
     // file may require a different (incompatible) state of the file system.
     //
     // FIXME: Make the compilation database interface more explicit about the

 
 } // namespace
 
 int ClangTool::buildASTs(std::vector<std::unique_ptr<ASTUnit>> &ASTs) {
   ASTBuilderAction Action(ASTs);
   return run(&Action);
 }
 
-void ClangTool::setRestoreWorkingDir(bool RestoreCWD) {
-  this->RestoreCWD = RestoreCWD;
-}
-
 void ClangTool::setPrintErrorMessage(bool PrintErrorMessage) {
   this->PrintErrorMessage = PrintErrorMessage;
 }
 
 namespace clang {
 namespace tooling {
 
 std::unique_ptr<ASTUnit>