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diff --git a/gdbsupport/hash_enum.h b/gdbsupport/hash_enum.h
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+/* A hasher for enums.
+
+   Copyright (C) 2017-2020 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef COMMON_HASH_ENUM_H
+#define COMMON_HASH_ENUM_H
+
+/* A hasher for enums, which was missing in C++11:
+    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2148
+*/
+
+namespace gdb {
+
+/* Helper struct for hashing enum types.  */
+template<typename T>
+struct hash_enum
+{
+  typedef size_t result_type;
+  typedef T argument_type;
+
+  size_t operator() (T val) const noexcept
+  {
+    using underlying = typename std::underlying_type<T>::type;
+    return std::hash<underlying> () (static_cast<underlying> (val));
+  }
+};
+
+} /* namespace gdb */
+
+#endif /* COMMON_HASH_ENUM_H */