1 files changed, 38 insertions, 0 deletions
diff --git a/src/boost/libs/hana/test/map/at_key.stackoverflow.cpp b/src/boost/libs/hana/test/map/at_key.stackoverflow.cpp
new file mode 100644
index 00000000..7f71799a
--- /dev/null
+++ b/src/boost/libs/hana/test/map/at_key.stackoverflow.cpp
@@ -0,0 +1,38 @@
+// Copyright Louis Dionne 2013-2017
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+#include <boost/hana/assert.hpp>
+#include <boost/hana/at_key.hpp>
+#include <boost/hana/fold_left.hpp>
+#include <boost/hana/integral_constant.hpp>
+#include <boost/hana/map.hpp>
+#include <boost/hana/pair.hpp>
+#include <boost/hana/range.hpp>
+namespace hana = boost::hana;
+
+
+//
+// Make sure that http://stackoverflow.com/q/32702383/627587 works.
+//
+
+auto at = [](auto& map, auto key) -> auto& {
+    return map[key];
+};
+
+template <typename Map, typename Keys>
+auto& traverse(Map& map, Keys const& keys){
+    return hana::fold_left(keys, map, at);
+}
+
+int main() {
+    auto xs = hana::make_map(hana::make_pair(hana::int_c<0>,
+                hana::make_map(hana::make_pair(hana::int_c<1>,
+                    hana::make_map(hana::make_pair(hana::int_c<2>,
+                        hana::make_map(hana::make_pair(hana::int_c<3>, 10))))))));
+
+    int& i = traverse(xs, hana::range_c<int, 0, 4>);
+    BOOST_HANA_RUNTIME_CHECK(i == 10);
+    i = 99;
+    BOOST_HANA_RUNTIME_CHECK(traverse(xs, hana::range_c<int, 0, 4>) == 99);
+}