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diff --git a/include/clang/Basic/Linkage.h b/include/clang/Basic/Linkage.h
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+//===--- Linkage.h - Linkage enumeration and utilities ----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the Linkage enumeration and various utility
+// functions.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_CLANG_BASIC_LINKAGE_H
+#define LLVM_CLANG_BASIC_LINKAGE_H
+
+namespace clang {
+
+/// \brief Describes the different kinds of linkage 
+/// (C++ [basic.link], C99 6.2.2) that an entity may have.
+enum Linkage {
+  /// \brief No linkage, which means that the entity is unique and
+  /// can only be referred to from within its scope.
+  NoLinkage = 0,
+
+  /// \brief Internal linkage, which indicates that the entity can
+  /// be referred to from within the translation unit (but not other
+  /// translation units).
+  InternalLinkage,
+
+  /// \brief External linkage within a unique namespace. From the
+  /// langauge perspective, these entities have external
+  /// linkage. However, since they reside in an anonymous namespace,
+  /// their names are unique to this translation unit, which is
+  /// equivalent to having internal linkage from the code-generation
+  /// point of view.
+  UniqueExternalLinkage,
+
+  /// \brief External linkage, which indicates that the entity can
+  /// be referred to from other translation units.
+  ExternalLinkage
+};
+
+/// \brief Determine whether the given linkage is semantically
+/// external.
+inline bool isExternalLinkage(Linkage L) {
+  return L == UniqueExternalLinkage || L == ExternalLinkage;
+}
+
+/// \brief Compute the minimum linkage given two linages.
+static inline Linkage minLinkage(Linkage L1, Linkage L2) {
+  return L1 < L2? L1 : L2;
+}
+
+} // end namespace clang
+
+#endif // LLVM_CLANG_BASIC_LINKAGE_H