[clang] [clang][DependencyScanning] Remove dependency on clangDriver from clangDependencyScanning (PR #169964)

[Jan Svoboda via cfe-commits]

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@@ -91,70 +93,72 @@ class DependencyScanningWorker {
 
   ~DependencyScanningWorker();
 
-  /// Run the dependency scanning tool for a given clang driver command-line,
-  /// and report the discovered dependencies to the provided consumer. If
-  /// TUBuffer is not nullopt, it is used as TU input for the dependency
-  /// scanning. Otherwise, the input should be included as part of the
-  /// command-line.
+  /// Run the dependency scanning tool for a given clang -cc1 command-line,
+  /// and report the discovered dependencies to the provided consumer.
   ///
-  /// \returns false if clang errors occurred (with diagnostics reported to
+  /// \return false if clang errors occurred (with diagnostics reported to
   /// \c DiagConsumer), true otherwise.
   bool computeDependencies(
       StringRef WorkingDirectory, const std::vector<std::string> &CommandLine,
       DependencyConsumer &DepConsumer, DependencyActionController &Controller,
       DiagnosticConsumer &DiagConsumer,
-      std::optional<llvm::MemoryBufferRef> TUBuffer = std::nullopt);
+      llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> ScanFS = nullptr);
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jansvoboda11 wrote:

Can we please keep this as `OverlayFS`? I personally have a hard time figuring out what all these VFSs flying around do, so being super clear what these are is helpful. Same for the internal functions below.

https://github.com/llvm/llvm-project/pull/169964