merge(3p/immer): Subtree merge at 'ad3e3556d' as 'third_party/immer'

Change-Id: I9636a41ad44b4218293833fd3e9456d9b07c731b

third_party/immer/example/vector/move.cpp

@@ -0,0 +1,35 @@
+//
+// 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
+//
+
+#include <cassert>
+#include <immer/vector.hpp>
+
+// include:move-bad/start
+immer::vector<int> do_stuff(const immer::vector<int> v)
+{
+    return std::move(v).push_back(42);
+}
+// include:move-bad/end
+
+// include:move-good/start
+immer::vector<int> do_stuff_better(immer::vector<int> v)
+{
+    return std::move(v).push_back(42);
+}
+// include:move-good/end
+
+int main()
+{
+    auto v  = immer::vector<int>{};
+    auto v1 = do_stuff(v);
+    auto v2 = do_stuff_better(v);
+    assert(v1.size() == 1);
+    assert(v2.size() == 1);
+    assert(v1[0] == 42);
+    assert(v2[0] == 42);
+}