Revert "[clang] Don't silently inherit the VFS from FileManager (#164323)"

breaks build/test of comgr

This reverts commit 866879f.

Author: ronlieb

clang-tools-extra/clang-include-fixer/IncludeFixer.cpp

@@ -90,7 +90,6 @@ bool IncludeFixerActionFactory::runInvocation(
 
   // Set up Clang.
   CompilerInstance Compiler(std::move(Invocation), std::move(PCHContainerOps));
-  Compiler.setVirtualFileSystem(Files->getVirtualFileSystemPtr());
   Compiler.setFileManager(Files);
 
   // Create the compiler's actual diagnostics engine. We want to drop all

clang/include/clang/Frontend/ASTUnit.h

@@ -499,11 +499,6 @@ class ASTUnit {
     return *PPOpts;
   }
 
-  IntrusiveRefCntPtr<llvm::vfs::FileSystem> getVirtualFileSystemPtr() {
-    // FIXME: Don't defer VFS ownership to the FileManager.
-    return FileMgr->getVirtualFileSystemPtr();
-  }
-
   const FileManager &getFileManager() const { return *FileMgr; }
   FileManager &getFileManager() { return *FileMgr; }
   IntrusiveRefCntPtr<FileManager> getFileManagerPtr() { return FileMgr; }

clang/include/clang/Frontend/CompilerInstance.h

@@ -460,7 +460,7 @@ class CompilerInstance : public ModuleLoader {
     FileMgr.resetWithoutRelease();
   }
 
-  /// Replace the current file manager.
+  /// Replace the current file manager and virtual file system.
   void setFileManager(IntrusiveRefCntPtr<FileManager> Value);
 
   /// @}

clang/lib/Frontend/ASTUnit.cpp

@@ -1646,7 +1646,6 @@ ASTUnit *ASTUnit::LoadFromCompilerInvocationAction(
   AST->Reader = nullptr;
 
   // Create a file manager object to provide access to and cache the filesystem.
-  Clang->setVirtualFileSystem(AST->getVirtualFileSystemPtr());
   Clang->setFileManager(AST->getFileManagerPtr());
 
   // Create the source manager.
@@ -2286,7 +2285,6 @@ void ASTUnit::CodeComplete(
          "IR inputs not support here!");
 
   // Use the source and file managers that we were given.
-  Clang->setVirtualFileSystem(FileMgr->getVirtualFileSystemPtr());
   Clang->setFileManager(FileMgr);
   Clang->setSourceManager(SourceMgr);
 

clang/lib/Frontend/CompilerInstance.cpp

@@ -160,6 +160,8 @@ bool CompilerInstance::createTarget() {
 }
 
 void CompilerInstance::setFileManager(IntrusiveRefCntPtr<FileManager> Value) {
+  if (!hasVirtualFileSystem())
+    setVirtualFileSystem(Value->getVirtualFileSystemPtr());
   assert(Value == nullptr ||
          getVirtualFileSystemPtr() == Value->getVirtualFileSystemPtr());
   FileMgr = std::move(Value);

clang/lib/Frontend/FrontendAction.cpp

@@ -945,7 +945,6 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
 
     // Set the shared objects, these are reset when we finish processing the
     // file, otherwise the CompilerInstance will happily destroy them.
-    CI.setVirtualFileSystem(AST->getVirtualFileSystemPtr());
     CI.setFileManager(AST->getFileManagerPtr());
     CI.setSourceManager(AST->getSourceManagerPtr());
     CI.setPreprocessor(AST->getPreprocessorPtr());

clang/lib/Frontend/PrecompiledPreamble.cpp

@@ -479,12 +479,16 @@ llvm::ErrorOr<PrecompiledPreamble> PrecompiledPreamble::Build(
   Diagnostics->Reset();
   ProcessWarningOptions(*Diagnostics, Clang->getDiagnosticOpts(), *VFS);
 
+  VFS = createVFSFromCompilerInvocation(Clang->getInvocation(), *Diagnostics,
+                                        VFS);
+
   // Create a file manager object to provide access to and cache the filesystem.
-  Clang->createVirtualFileSystem(VFS);
-  Clang->createFileManager();
+  Clang->setFileManager(
+      llvm::makeIntrusiveRefCnt<FileManager>(Clang->getFileSystemOpts(), VFS));
 
   // Create the source manager.
-  Clang->createSourceManager();
+  Clang->setSourceManager(llvm::makeIntrusiveRefCnt<SourceManager>(
+      *Diagnostics, Clang->getFileManager()));
 
   auto PreambleDepCollector = std::make_shared<PreambleDependencyCollector>();
   Clang->addDependencyCollector(PreambleDepCollector);

clang/lib/StaticAnalyzer/Frontend/ModelInjector.cpp

@@ -93,7 +93,6 @@ void ModelInjector::onBodySynthesis(const NamedDecl *D) {
 
   // The instance wants to take ownership, however DisableFree frontend option
   // is set to true to avoid double free issues
-  Instance.setVirtualFileSystem(CI.getVirtualFileSystemPtr());
   Instance.setFileManager(CI.getFileManagerPtr());
   Instance.setSourceManager(SM);
   Instance.setPreprocessor(CI.getPreprocessorPtr());

clang/lib/Tooling/Tooling.cpp

@@ -446,7 +446,6 @@ bool FrontendActionFactory::runInvocation(
     DiagnosticConsumer *DiagConsumer) {
   // Create a compiler instance to handle the actual work.
   CompilerInstance Compiler(std::move(Invocation), std::move(PCHContainerOps));
-  Compiler.setVirtualFileSystem(Files->getVirtualFileSystemPtr());
   Compiler.setFileManager(Files);
 
   // The FrontendAction can have lifetime requirements for Compiler or its

clang/tools/clang-installapi/ClangInstallAPI.cpp

@@ -114,7 +114,6 @@ static bool run(ArrayRef<const char *> Args, const char *ProgName) {
 
   // Set up compilation.
   std::unique_ptr<CompilerInstance> CI(new CompilerInstance());
-  CI->setVirtualFileSystem(FM->getVirtualFileSystemPtr());
   CI->setFileManager(FM);
   CI->createDiagnostics();
   if (!CI->hasDiagnostics())