Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/src/boost/libs/hana/test/fold_left/ref.cpp b/src/boost/libs/hana/test/fold_left/ref.cpp
new file mode 100644
index 00000000..a2b34ad6
--- /dev/null
+++ b/src/boost/libs/hana/test/fold_left/ref.cpp
@@ -0,0 +1,40 @@
+// 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.hpp>
+#include <boost/hana/fold_left.hpp>
+#include <boost/hana/tuple.hpp>
+namespace hana = boost::hana;
+
+//
+// Make sure that we can fold_left and take arguments by reference.
+//
+
+int main() {
+    // with state
+    {
+        auto xs = hana::make_tuple(1, 2, 3);
+        int state = 99;
+
+        int& three = hana::fold_left(xs, state, [](int&, int& i) -> int& {
+            return i;
+        });
+        BOOST_HANA_RUNTIME_CHECK(three == 3);
+        three = 10;
+        BOOST_HANA_RUNTIME_CHECK(hana::at_c<2>(xs) == 10);
+    }
+
+    // without state
+    {
+        auto xs = hana::make_tuple(1, 2, 3);
+
+        int& three = hana::fold_left(xs, [](int&, int& i) -> int& {
+            return i;
+        });
+        BOOST_HANA_RUNTIME_CHECK(three == 3);
+        three = 10;
+        BOOST_HANA_RUNTIME_CHECK(hana::at_c<2>(xs) == 10);
+    }
+}