clang/Basic: Replace SourceManager::getMemoryBufferForFile, NFC

Replace `SourceManager::getMemoryBufferForFile`, which returned a
dereferenceable `MemoryBuffer*` and had a `bool*Invalid` out parameter,
with `getMemoryBufferForFileOrNone` (returning
`Optional<MemoryBufferRef>`) and `getMemoryBufferForFileOrFake`
(returning `MemoryBufferRef`).

Differential Revision: https://reviews.llvm.org/D89429

clang/include/clang/Basic/SourceManager.h

@@ -901,10 +901,18 @@ public:
 
   /// Retrieve the memory buffer associated with the given file.
   ///
-  /// \param Invalid If non-NULL, will be set \c true if an error
-  /// occurs while retrieving the memory buffer.
-  const llvm::MemoryBuffer *getMemoryBufferForFile(const FileEntry *File,
-                                                   bool *Invalid = nullptr);
+  /// Returns None if the buffer is not valid.
+  llvm::Optional<llvm::MemoryBufferRef>
+  getMemoryBufferForFileOrNone(const FileEntry *File);
+
+  /// Retrieve the memory buffer associated with the given file.
+  ///
+  /// Returns a fake buffer if there isn't a real one.
+  llvm::MemoryBufferRef getMemoryBufferForFileOrFake(const FileEntry *File) {
+    if (auto B = getMemoryBufferForFileOrNone(File))
+      return *B;
+    return getFakeBufferForRecovery()->getMemBufferRef();
+  }
 
   /// Override the contents of the given source file by providing an
   /// already-allocated buffer.

clang/include/clang/Frontend/PrecompiledPreamble.h

@@ -26,6 +26,7 @@
 
 namespace llvm {
 class MemoryBuffer;
+class MemoryBufferRef;
 namespace vfs {
 class FileSystem;
 }
@@ -216,7 +217,7 @@ private:
 
     static PreambleFileHash createForFile(off_t Size, time_t ModTime);
     static PreambleFileHash
-    createForMemoryBuffer(const llvm::MemoryBuffer *Buffer);
+    createForMemoryBuffer(const llvm::MemoryBufferRef &Buffer);
 
     friend bool operator==(const PreambleFileHash &LHS,
                            const PreambleFileHash &RHS) {

clang/lib/Basic/SourceManager.cpp

@@ -701,14 +701,11 @@ SourceManager::createExpansionLocImpl(const ExpansionInfo &Info,
   return SourceLocation::getMacroLoc(NextLocalOffset - (TokLength + 1));
 }
 
-const llvm::MemoryBuffer *
-SourceManager::getMemoryBufferForFile(const FileEntry *File, bool *Invalid) {
+llvm::Optional<llvm::MemoryBufferRef>
+SourceManager::getMemoryBufferForFileOrNone(const FileEntry *File) {
   const SrcMgr::ContentCache *IR = getOrCreateContentCache(File);
   assert(IR && "getOrCreateContentCache() cannot return NULL");
-  auto *B = IR->getBufferPointer(Diag, getFileManager(), SourceLocation());
-  if (Invalid)
-    *Invalid = !B;
-  return B ? B : getFakeBufferForRecovery();
+  return IR->getBufferOrNone(Diag, getFileManager(), SourceLocation());
 }
 
 void SourceManager::overrideFileContents(const FileEntry *SourceFile,

clang/lib/Frontend/PrecompiledPreamble.cpp

@@ -463,7 +463,8 @@ llvm::ErrorOr<PrecompiledPreamble> PrecompiledPreamble::Build(
           PrecompiledPreamble::PreambleFileHash::createForFile(File->getSize(),
                                                                ModTime);
     } else {
-      const llvm::MemoryBuffer *Buffer = SourceMgr.getMemoryBufferForFile(File);
+      llvm::MemoryBufferRef Buffer =
+          SourceMgr.getMemoryBufferForFileOrFake(File);
       FilesInPreamble[File->getName()] =
           PrecompiledPreamble::PreambleFileHash::createForMemoryBuffer(Buffer);
     }
@@ -549,7 +550,7 @@ bool PrecompiledPreamble::CanReuse(const CompilerInvocation &Invocation,
   llvm::StringMap<PreambleFileHash> OverridenFileBuffers;
   for (const auto &RB : PreprocessorOpts.RemappedFileBuffers) {
     const PrecompiledPreamble::PreambleFileHash PreambleHash =
-        PreambleFileHash::createForMemoryBuffer(RB.second);
+        PreambleFileHash::createForMemoryBuffer(RB.second->getMemBufferRef());
     llvm::vfs::Status Status;
     if (moveOnNoError(VFS->status(RB.first), Status))
       OverriddenFiles[Status.getUniqueID()] = PreambleHash;
@@ -783,13 +784,13 @@ PrecompiledPreamble::PreambleFileHash::createForFile(off_t Size,
 
 PrecompiledPreamble::PreambleFileHash
 PrecompiledPreamble::PreambleFileHash::createForMemoryBuffer(
-    const llvm::MemoryBuffer *Buffer) {
+    const llvm::MemoryBufferRef &Buffer) {
   PreambleFileHash Result;
-  Result.Size = Buffer->getBufferSize();
+  Result.Size = Buffer.getBufferSize();
   Result.ModTime = 0;
 
   llvm::MD5 MD5Ctx;
-  MD5Ctx.update(Buffer->getBuffer().data());
+  MD5Ctx.update(Buffer.getBuffer().data());
   MD5Ctx.final(Result.MD5);
 
   return Result;

clang/lib/Lex/Preprocessor.cpp

@@ -395,12 +395,10 @@ bool Preprocessor::SetCodeCompletionPoint(const FileEntry *File,
   assert(CompleteLine && CompleteColumn && "Starts from 1:1");
   assert(!CodeCompletionFile && "Already set");
 
-  using llvm::MemoryBuffer;
-
   // Load the actual file's contents.
-  bool Invalid = false;
-  const MemoryBuffer *Buffer = SourceMgr.getMemoryBufferForFile(File, &Invalid);
-  if (Invalid)
+  Optional<llvm::MemoryBufferRef> Buffer =
+      SourceMgr.getMemoryBufferForFileOrNone(File);
+  if (!Buffer)
     return true;
 
   // Find the byte position of the truncation point.