[clang] Pass VFS into ASTUnit::LoadFromASTFile() (llvm#159166)

This PR makes the `VFS` parameter to `ASTUnit::LoadFromASTFile()`
required and explicit, rather than silently defaulting to the real file
system. This makes it easy to correctly propagate the fully-configured
VFS and load any input files like the rest of the compiler does.

(cherry picked from commit cda542d)

Author: jansvoboda11

clang/include/clang/Frontend/ASTUnit.h

@@ -716,16 +716,15 @@ class ASTUnit {
   /// \returns - The initialized ASTUnit or null if the AST failed to load.
   static std::unique_ptr<ASTUnit> LoadFromASTFile(
       StringRef Filename, const PCHContainerReader &PCHContainerRdr,
-      WhatToLoad ToLoad, std::shared_ptr<DiagnosticOptions> DiagOpts,
+      WhatToLoad ToLoad, IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
+      std::shared_ptr<DiagnosticOptions> DiagOpts,
       IntrusiveRefCntPtr<DiagnosticsEngine> Diags,
       const FileSystemOptions &FileSystemOpts,
       const HeaderSearchOptions &HSOpts, const LangOptions *LangOpts = nullptr,
       bool OnlyLocalDecls = false,
       CaptureDiagsKind CaptureDiagnostics = CaptureDiagsKind::None,
       bool AllowASTWithCompilerErrors = false,
-      bool UserFilesAreVolatile = false,
-      IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS =
-          llvm::vfs::getRealFileSystem());
+      bool UserFilesAreVolatile = false);
 
 private:
   /// Helper function for \c LoadFromCompilerInvocation() and

clang/lib/CrossTU/CrossTranslationUnit.cpp

@@ -567,8 +567,8 @@ CrossTranslationUnitContext::ASTLoader::loadFromDump(StringRef ASTDumpPath) {
       DiagnosticIDs::create(), *DiagOpts, DiagClient);
   return ASTUnit::LoadFromASTFile(
       ASTDumpPath, CI.getPCHContainerOperations()->getRawReader(),
-      ASTUnit::LoadEverything, DiagOpts, Diags, CI.getFileSystemOpts(),
-      CI.getHeaderSearchOpts());
+      ASTUnit::LoadEverything, CI.getVirtualFileSystemPtr(), DiagOpts, Diags,
+      CI.getFileSystemOpts(), CI.getHeaderSearchOpts());
 }
 
 /// Load the AST from a source-file, which is supposed to be located inside the

clang/lib/Frontend/ASTMerge.cpp

@@ -47,7 +47,8 @@ void ASTMergeAction::ExecuteAction() {
         /*ShouldOwnClient=*/true);
     std::unique_ptr<ASTUnit> Unit = ASTUnit::LoadFromASTFile(
         ASTFiles[I], CI.getPCHContainerReader(), ASTUnit::LoadEverything,
-        nullptr, Diags, CI.getFileSystemOpts(), CI.getHeaderSearchOpts());
+        CI.getVirtualFileSystemPtr(), nullptr, Diags, CI.getFileSystemOpts(),
+        CI.getHeaderSearchOpts());
 
     if (!Unit)
       continue;

clang/lib/Frontend/ASTUnit.cpp

@@ -799,12 +799,13 @@ void ASTUnit::ConfigureDiags(IntrusiveRefCntPtr<DiagnosticsEngine> Diags,
 
 std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile(
     StringRef Filename, const PCHContainerReader &PCHContainerRdr,
-    WhatToLoad ToLoad, std::shared_ptr<DiagnosticOptions> DiagOpts,
+    WhatToLoad ToLoad, IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
+    std::shared_ptr<DiagnosticOptions> DiagOpts,
     IntrusiveRefCntPtr<DiagnosticsEngine> Diags,
     const FileSystemOptions &FileSystemOpts, const HeaderSearchOptions &HSOpts,
     const LangOptions *LangOpts, bool OnlyLocalDecls,
     CaptureDiagsKind CaptureDiagnostics, bool AllowASTWithCompilerErrors,
-    bool UserFilesAreVolatile, IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS) {
+    bool UserFilesAreVolatile) {
   std::unique_ptr<ASTUnit> AST(new ASTUnit(true));
 
   // Recover resources if we crash before exiting this method.

clang/lib/Frontend/FrontendAction.cpp

@@ -904,7 +904,8 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
 
     std::unique_ptr<ASTUnit> AST = ASTUnit::LoadFromASTFile(
         InputFile, CI.getPCHContainerReader(), ASTUnit::LoadPreprocessorOnly,
-        nullptr, ASTDiags, CI.getFileSystemOpts(), CI.getHeaderSearchOpts());
+        CI.getVirtualFileSystemPtr(), nullptr, ASTDiags, CI.getFileSystemOpts(),
+        CI.getHeaderSearchOpts());
     if (!AST)
       return false;
 
@@ -971,9 +972,9 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
     StringRef InputFile = Input.getFile();
 
     std::unique_ptr<ASTUnit> AST = ASTUnit::LoadFromASTFile(
-        InputFile, CI.getPCHContainerReader(), ASTUnit::LoadEverything, nullptr,
-        Diags, CI.getFileSystemOpts(), CI.getHeaderSearchOpts(),
-        &CI.getLangOpts());
+        InputFile, CI.getPCHContainerReader(), ASTUnit::LoadEverything,
+        CI.getVirtualFileSystemPtr(), nullptr, Diags, CI.getFileSystemOpts(),
+        CI.getHeaderSearchOpts(), &CI.getLangOpts());
 
     if (!AST)
       return false;

clang/tools/c-index-test/core_main.cpp

@@ -369,12 +369,13 @@ static bool printSourceSymbolsFromModule(StringRef modulePath,
 
   HeaderSearchOptions HSOpts;
 
+  auto VFS = llvm::vfs::getRealFileSystem();
+
   auto DiagOpts = std::make_shared<DiagnosticOptions>();
   IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
-      CompilerInstance::createDiagnostics(*llvm::vfs::getRealFileSystem(),
-                                          *DiagOpts);
+      CompilerInstance::createDiagnostics(*VFS, *DiagOpts);
   std::unique_ptr<ASTUnit> AU = ASTUnit::LoadFromASTFile(
-      modulePath, *pchRdr, ASTUnit::LoadASTOnly, DiagOpts, Diags,
+      modulePath, *pchRdr, ASTUnit::LoadASTOnly, VFS, DiagOpts, Diags,
       FileSystemOpts, HSOpts, /*LangOpts=*/nullptr,
       /*OnlyLocalDecls=*/true, CaptureDiagsKind::None,
       /*AllowASTWithCompilerErrors=*/true,

clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp

@@ -157,8 +157,8 @@ static bool HandleAST(StringRef AstPath) {
 
   std::unique_ptr<ASTUnit> Unit = ASTUnit::LoadFromASTFile(
       AstPath, CI->getPCHContainerOperations()->getRawReader(),
-      ASTUnit::LoadASTOnly, DiagOpts, DiagEngine, CI->getFileSystemOpts(),
-      CI->getHeaderSearchOpts());
+      ASTUnit::LoadASTOnly, CI->getVirtualFileSystemPtr(), DiagOpts, DiagEngine,
+      CI->getFileSystemOpts(), CI->getHeaderSearchOpts());
 
   if (!Unit)
     return false;

clang/tools/libclang/CIndex.cpp

@@ -4243,13 +4243,14 @@ enum CXErrorCode clang_createTranslationUnit2(CXIndex CIdx,
   FileSystemOptions FileSystemOpts;
   HeaderSearchOptions HSOpts;
 
+  auto VFS = llvm::vfs::getRealFileSystem();
+
   auto DiagOpts = std::make_shared<DiagnosticOptions>();
   IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
-      CompilerInstance::createDiagnostics(*llvm::vfs::getRealFileSystem(),
-                                          *DiagOpts);
+      CompilerInstance::createDiagnostics(*VFS, *DiagOpts);
   std::unique_ptr<ASTUnit> AU = ASTUnit::LoadFromASTFile(
       ast_filename, CXXIdx->getPCHContainerOperations()->getRawReader(),
-      ASTUnit::LoadEverything, DiagOpts, Diags, FileSystemOpts, HSOpts,
+      ASTUnit::LoadEverything, VFS, DiagOpts, Diags, FileSystemOpts, HSOpts,
       /*LangOpts=*/nullptr, CXXIdx->getOnlyLocalDecls(), CaptureDiagsKind::All,
       /*AllowASTWithCompilerErrors=*/true,
       /*UserFilesAreVolatile=*/true);

clang/unittests/Frontend/ASTUnitTest.cpp

@@ -98,7 +98,8 @@ TEST_F(ASTUnitTest, SaveLoadPreservesLangOptionsInPrintingPolicy) {
 
   std::unique_ptr<ASTUnit> AU = ASTUnit::LoadFromASTFile(
       ASTFileName, PCHContainerOps->getRawReader(), ASTUnit::LoadEverything,
-      DiagOpts, Diags, FileSystemOptions(), HSOpts);
+      llvm::vfs::getRealFileSystem(), DiagOpts, Diags, FileSystemOptions(),
+      HSOpts);
 
   if (!AU)
     FAIL() << "failed to load ASTUnit";