[Tooling] Restore working dir in ClangTool.

Summary:
And add an option to disable this behavior. The option is only used in
AllTUsExecutor to avoid races when running concurrently on multiple
threads.

This fixes PR38869 introduced by r340937.

Reviewers: ioeric, steveire

Reviewed By: ioeric

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D51864

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@341910 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/Tooling/Tooling.cpp b/lib/Tooling/Tooling.cpp
index 1ec285cc47..395d2d7a04 100644
--- a/lib/Tooling/Tooling.cpp
+++ b/lib/Tooling/Tooling.cpp
@@ -441,6 +441,17 @@ int ClangTool::run(ToolAction *Action) {
     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
@@ -508,6 +519,13 @@ int ClangTool::run(ToolAction *Action) {
       }
     }
   }
+
+  if (!InitialWorkingDir.empty()) {
+    if (auto EC =
+            OverlayFileSystem->setCurrentWorkingDirectory(InitialWorkingDir))
+      llvm::errs() << "Error when trying to restore working dir: "
+                   << EC.message() << "\n";
+  }
   return ProcessingFailed ? 1 : (FileSkipped ? 2 : 0);
 }
 
@@ -544,6 +562,10 @@ int ClangTool::buildASTs(std::vector<std::unique_ptr<ASTUnit>> &ASTs) {
   return run(&Action);
 }
 
+void ClangTool::setRestoreWorkingDir(bool RestoreCWD) {
+  this->RestoreCWD = RestoreCWD;
+}
+
 namespace clang {
 namespace tooling {