[clang] [APINotes] Upstream APINotesReader (PR #66769)

[Saleem Abdulrasool via cfe-commits]

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@@ -0,0 +1,202 @@
+//===--- APINotesReader.h - API Notes Reader --------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the \c APINotesReader class that reads source API notes
+// data providing additional information about source code as a separate input,
+// such as the non-nil/nilable annotations for method parameters.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_APINOTES_READER_H
+#define LLVM_CLANG_APINOTES_READER_H
+
+#include "clang/APINotes/Types.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/VersionTuple.h"
+#include <memory>
+
+namespace clang {
+namespace api_notes {
+
+/// A class that reads API notes data from a binary file that was written by
+/// the \c APINotesWriter.
+class APINotesReader {
+  class Implementation;
+  std::unique_ptr<Implementation> Implementation;
+
+  APINotesReader(llvm::MemoryBuffer *InputBuffer,
+                 llvm::VersionTuple SwiftVersion, bool &Failed);
+
+public:
+  /// Create a new API notes reader from the given member buffer, which
+  /// contains the contents of a binary API notes file.
+  ///
+  /// \returns the new API notes reader, or null if an error occurred.
+  static std::unique_ptr<APINotesReader>
+  get(std::unique_ptr<llvm::MemoryBuffer> InputBuffer,
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compnerd wrote:

`Create` would be more inline with the rest of the project.

https://github.com/llvm/llvm-project/pull/66769