Verify o3tl::temporary of a copied lvalue works as expected

Change-Id: I454dd9308e7da4c7be4751eb643395ac483d6c43
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/108939
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

o3tl/CppunitTest_o3tl_tests.mk

@@ -33,6 +33,7 @@ $(eval $(call gb_CppunitTest_add_exception_objects,o3tl_tests,\
 	o3tl/qa/test-safeint \
 	o3tl/qa/test-sorted_vector \
 	o3tl/qa/test-span \
+	o3tl/qa/test-temporary \
 	o3tl/qa/test-typed_flags \
 	o3tl/qa/test-vector_pool \
 ))

o3tl/qa/test-temporary.cxx

@@ -0,0 +1,47 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <sal/config.h>
+
+#include <cppunit/TestAssert.h>
+#include <cppunit/TestFixture.h>
+#include <cppunit/extensions/HelperMacros.h>
+
+#include <o3tl/temporary.hxx>
+
+namespace
+{
+void modify(int& n) { n = 1; }
+
+class Test : public CppUnit::TestFixture
+{
+private:
+    CPPUNIT_TEST_SUITE(Test);
+    CPPUNIT_TEST(testLvalue);
+    CPPUNIT_TEST_SUITE_END();
+
+    void testLvalue()
+    {
+        {
+            int n = 0;
+            modify(n);
+            CPPUNIT_ASSERT_EQUAL(1, n);
+        }
+        {
+            int n = 0;
+            modify(o3tl::temporary(int(n)));
+            CPPUNIT_ASSERT_EQUAL(0, n);
+        }
+    }
+};
+
+CPPUNIT_TEST_SUITE_REGISTRATION(Test);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */