1 files changed, 49 insertions, 0 deletions
diff --git a/extra/guile/scm/detail/util.hpp b/extra/guile/scm/detail/util.hpp
new file mode 100644
index 000000000000..fdc323722e99
--- /dev/null
+++ b/extra/guile/scm/detail/util.hpp
@@ -0,0 +1,49 @@
+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#pragma once
+
+#include <libguile.h>
+
+namespace scm {
+namespace detail {
+
+#define SCM_DECLTYPE_RETURN(...)                \
+    decltype(__VA_ARGS__)                       \
+    { return __VA_ARGS__; }                     \
+    /**/
+
+template <typename... Ts>
+constexpr bool is_valid_v = true;
+
+template <typename... Ts>
+using is_valid_t = void;
+
+template <typename... Ts>
+void check_call_once()
+{
+    static bool called = false;
+    if (called) scm_misc_error (nullptr, "Double defined binding. \
+This may be caused because there are multiple C++ binding groups in the same \
+translation unit.  You may solve this by using different type tags for each \
+binding group.", SCM_EOL);
+    called = true;
+}
+
+struct move_sequence
+{
+    move_sequence() = default;
+    move_sequence(const move_sequence&) = delete;
+    move_sequence(move_sequence&& other)
+    { other.moved_from_ = true; };
+
+    bool moved_from_ = false;
+};
+
+} // namespace detail
+} // namespace scm