[clang][DependencyScanning] Unify initVFS helpers to return OverlayFileSystem (NFC)

[naveen-seth]

This patch is part of a series of splitting the work from #169964 into smaller changes (see review linked below).

As part of this work, the regular and by-name dependency scanning APIs need to be extended to allow the VFS to be initialized via the initVFS- helpers before invoking the scanning API, with the resulting overlay filesystem passed into the worker instead.

To make the newly added API changes consistent, this patch updates both helpers to return an OverlayFileSystem.

#169964 (review)

[llvmbot]

@llvm/pr-subscribers-clang

Author: Naveen Seth Hanig (naveen-seth)

Changes

This patch is part of a series of splitting the work from #169964 into smaller changes (see review linked below).

As part of this work, the regular and by-name dependency scanning APIs need to be extended to allow the VFS to be initialized via the initVFS- helpers before invoking the scanning API, with the resulting overlay filesystem passed into the worker instead.

To make the newly added API changes consistent, this patch updates both helpers to return an OverlayFileSystem.

#169964 (review)

---

Full diff: https://github.com/llvm/llvm-project/pull/172166.diff

2 Files Affected:

• (modified) clang/include/clang/DependencyScanning/DependencyScannerImpl.h (+2-1)
• (modified) clang/lib/DependencyScanning/DependencyScannerImpl.cpp (+3-4)

diff --git a/clang/include/clang/DependencyScanning/DependencyScannerImpl.h b/clang/include/clang/DependencyScanning/DependencyScannerImpl.h
index 9e23c0f87f273..f43c7f70183fd 100644
--- a/clang/include/clang/DependencyScanning/DependencyScannerImpl.h
+++ b/clang/include/clang/DependencyScanning/DependencyScannerImpl.h
@@ -98,7 +98,8 @@ std::unique_ptr<CompilerInvocation>
 createCompilerInvocation(ArrayRef<std::string> CommandLine,
                          DiagnosticsEngine &Diags);
 
-std::pair<IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::vector<std::string>>
+std::pair<IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem>,
+          std::vector<std::string>>
 initVFSForTUBufferScanning(IntrusiveRefCntPtr<llvm::vfs::FileSystem> BaseFS,
                            ArrayRef<std::string> CommandLine,
                            StringRef WorkingDirectory,
diff --git a/clang/lib/DependencyScanning/DependencyScannerImpl.cpp b/clang/lib/DependencyScanning/DependencyScannerImpl.cpp
index 191ffabeea4f2..201230d7d6a8e 100644
--- a/clang/lib/DependencyScanning/DependencyScannerImpl.cpp
+++ b/clang/lib/DependencyScanning/DependencyScannerImpl.cpp
@@ -430,7 +430,8 @@ dependencies::createCompilerInvocation(ArrayRef<std::string> CommandLine,
   return Invocation;
 }
 
-std::pair<IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::vector<std::string>>
+std::pair<IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem>,
+          std::vector<std::string>>
 dependencies::initVFSForTUBufferScanning(
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> BaseFS,
     ArrayRef<std::string> CommandLine, StringRef WorkingDirectory,
@@ -438,7 +439,6 @@ dependencies::initVFSForTUBufferScanning(
   // Reset what might have been modified in the previous worker invocation.
   BaseFS->setCurrentWorkingDirectory(WorkingDirectory);
 
-  IntrusiveRefCntPtr<llvm::vfs::FileSystem> ModifiedFS;
   auto OverlayFS =
       llvm::makeIntrusiveRefCnt<llvm::vfs::OverlayFileSystem>(BaseFS);
   auto InMemoryFS = llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
@@ -449,11 +449,10 @@ dependencies::initVFSForTUBufferScanning(
   IntrusiveRefCntPtr<llvm::vfs::FileSystem> InMemoryOverlay = InMemoryFS;
 
   OverlayFS->pushOverlay(InMemoryOverlay);
-  ModifiedFS = OverlayFS;
   std::vector<std::string> ModifiedCommandLine(CommandLine);
   ModifiedCommandLine.emplace_back(InputPath);
 
-  return std::make_pair(ModifiedFS, ModifiedCommandLine);
+  return std::make_pair(OverlayFS, ModifiedCommandLine);
 }
 
 std::pair<IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem>,

[naveen-seth]

For additional context, the newly added calls in #169964 all accept an OverlayFileSystem:

llvm-project/clang/lib/DependencyScanning/DependencyScanningWorker.cpp

Lines 186 to 189 in fa1dceb

	bool DependencyScanningWorker::initializeCompilerInstanceWithContext(
	StringRef CWD, ArrayRef<std::string> CommandLine,
	std::unique_ptr<DiagnosticsEngineWithDiagOpts> DiagEngineWithDiagOpts,
	IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> OverlayFS) {

Because I want the upcoming additions to computeDependencies to be consistent with this and also accept an OverlayFileSystem, this aligns the return types of the helpers.