Basic: Return a reference from FileManager::getVirtualFileSystem, NFC

FileManager constructs a VFS in its constructor if it isn't passed one,
and there's no way to reset it.  Make that contract clear by returning a
reference from its accessor.

https://reviews.llvm.org/D59388

llvm-svn: 357038

3 files changed, 14 insertions, 13 deletions

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 7bc3010fcad..6a78b93b205 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -1079,7 +1079,7 @@ bool ASTUnit::Parse(std::shared_ptr<PCHContainerOperations> PCHContainerOps,
     return true;
 
   if (VFS && FileMgr)
-    assert(VFS == FileMgr->getVirtualFileSystem() &&
+    assert(VFS == &FileMgr->getVirtualFileSystem() &&
            "VFS passed to Parse and VFS in FileMgr are different");
 
   auto CCInvocation = std::make_shared<CompilerInvocation>(*Invocation);
@@ -1097,7 +1097,7 @@ bool ASTUnit::Parse(std::shared_ptr<PCHContainerOperations> PCHContainerOps,
   // Ensure that Clang has a FileManager with the right VFS, which may have
   // changed above in AddImplicitPreamble.  If VFS is nullptr, rely on
   // createFileManager to create one.
-  if (VFS && FileMgr && FileMgr->getVirtualFileSystem() == VFS)
+  if (VFS && FileMgr && &FileMgr->getVirtualFileSystem() == VFS)
     Clang->setFileManager(&*FileMgr);
   else
     FileMgr = Clang->createFileManager(std::move(VFS));
@@ -1690,7 +1690,7 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromCompilerInvocation(
 
   if (AST->LoadFromCompilerInvocation(std::move(PCHContainerOps),
                                       PrecompilePreambleAfterNParses,
-                                      AST->FileMgr->getVirtualFileSystem()))
+                                      &AST->FileMgr->getVirtualFileSystem()))
     return nullptr;
   return AST;
 }
@@ -1797,7 +1797,7 @@ bool ASTUnit::Reparse(std::shared_ptr<PCHContainerOperations> PCHContainerOps,
 
   if (!VFS) {
     assert(FileMgr && "FileMgr is null on Reparse call");
-    VFS = FileMgr->getVirtualFileSystem();
+    VFS = &FileMgr->getVirtualFileSystem();
   }
 
   clearFileLevelDecls();
@@ -2211,18 +2211,18 @@ void ASTUnit::CodeComplete(
   if (Preamble) {
     std::string CompleteFilePath(File);
 
-    auto VFS = FileMgr.getVirtualFileSystem();
-    auto CompleteFileStatus = VFS->status(CompleteFilePath);
+    auto &VFS = FileMgr.getVirtualFileSystem();
+    auto CompleteFileStatus = VFS.status(CompleteFilePath);
     if (CompleteFileStatus) {
       llvm::sys::fs::UniqueID CompleteFileID = CompleteFileStatus->getUniqueID();
 
       std::string MainPath(OriginalSourceFile);
-      auto MainStatus = VFS->status(MainPath);
+      auto MainStatus = VFS.status(MainPath);
       if (MainStatus) {
         llvm::sys::fs::UniqueID MainID = MainStatus->getUniqueID();
         if (CompleteFileID == MainID && Line > 1)
           OverrideMainBuffer = getMainBufferWithPrecompiledPreamble(
-              PCHContainerOps, Inv, VFS, false, Line - 1);
+              PCHContainerOps, Inv, &VFS, false, Line - 1);
       }
     }
   }
@@ -2233,7 +2233,8 @@ void ASTUnit::CodeComplete(
     assert(Preamble &&
            "No preamble was built, but OverrideMainBuffer is not null");
 
-    auto VFS = FileMgr.getVirtualFileSystem();
+    IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS =
+        &FileMgr.getVirtualFileSystem();
     Preamble->AddImplicitPreamble(Clang->getInvocation(), VFS,
                                   OverrideMainBuffer.get());
     // FIXME: there is no way to update VFS if it was changed by
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 6c82a6e9532..559bdb3c0e5 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -169,7 +169,7 @@ static void collectIncludePCH(CompilerInstance &CI,
   std::error_code EC;
   SmallString<128> DirNative;
   llvm::sys::path::native(PCHDir->getName(), DirNative);
-  llvm::vfs::FileSystem &FS = *FileMgr.getVirtualFileSystem();
+  llvm::vfs::FileSystem &FS = FileMgr.getVirtualFileSystem();
   SimpleASTReaderListener Validator(CI.getPreprocessor());
   for (llvm::vfs::directory_iterator Dir = FS.dir_begin(DirNative, EC), DirEnd;
        Dir != DirEnd && !EC; Dir.increment(EC)) {
@@ -296,7 +296,7 @@ CompilerInstance::createDiagnostics(DiagnosticOptions *Opts,
 FileManager *CompilerInstance::createFileManager(
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS) {
   if (!VFS)
-    VFS = FileMgr ? FileMgr->getVirtualFileSystem()
+    VFS = FileMgr ? &FileMgr->getVirtualFileSystem()
                   : createVFSFromCompilerInvocation(getInvocation(),
                                                     getDiagnostics());
   assert(VFS && "FileManager has no VFS?");
diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
index 3392923380f..2f4f5ef64c2 100644
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -360,7 +360,7 @@ static std::error_code collectModuleHeaderIncludes(
     SmallString<128> DirNative;
     llvm::sys::path::native(UmbrellaDir.Entry->getName(), DirNative);
 
-    llvm::vfs::FileSystem &FS = *FileMgr.getVirtualFileSystem();
+    llvm::vfs::FileSystem &FS = FileMgr.getVirtualFileSystem();
     for (llvm::vfs::recursive_directory_iterator Dir(FS, DirNative, EC), End;
          Dir != End && !EC; Dir.increment(EC)) {
       // Check whether this entry has an extension typically associated with
@@ -714,7 +714,7 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
       SmallString<128> DirNative;
       llvm::sys::path::native(PCHDir->getName(), DirNative);
       bool Found = false;
-      llvm::vfs::FileSystem &FS = *FileMgr.getVirtualFileSystem();
+      llvm::vfs::FileSystem &FS = FileMgr.getVirtualFileSystem();
       for (llvm::vfs::directory_iterator Dir = FS.dir_begin(DirNative, EC),
                                          DirEnd;
            Dir != DirEnd && !EC; Dir.increment(EC)) {