Add tests for CompactStorage

They're too trivial for their own QTestLib-based approach, but we
don't want them in the header, either, reducing the compile times for
all users, so put them into an otherwise empty .cpp file.

Change-Id: Iae7fc4d4a29a0648b91752040854288e02da7045
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/CMakeLists.txt

@@ -281,7 +281,7 @@ qt_internal_add_module(Core
         tools/qduplicatetracker_p.h
         tools/qflatmap_p.h
         tools/qfreelist.cpp tools/qfreelist_p.h
-        tools/qfunctionaltools_impl.h
+        tools/qfunctionaltools_impl.cpp tools/qfunctionaltools_impl.h
         tools/qhashfunctions.h
         tools/qiterator.h
         tools/qline.cpp tools/qline.h

src/corelib/tools/qfunctionaltools_impl.cpp

@@ -0,0 +1,47 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include <QtCore/qfunctionaltools_impl.h>
+
+// Remove this file once we have tests that implicitly test all aspects of
+// CompactStorage
+
+QT_BEGIN_NAMESPACE
+
+namespace QtPrivate {
+
+#define FOR_EACH_CVREF(op) \
+    op(&) \
+    op(const &) \
+    op(&&) \
+    op(const &&) \
+    /* end */
+
+namespace _testing {
+    struct empty {};
+    struct final final {};
+    static_assert(std::is_same_v<CompactStorage<empty>,
+                                 detail::StorageEmptyBaseClassOptimization<empty>>);
+    static_assert(std::is_same_v<CompactStorage<final>,
+                                 detail::StorageByValue<final>>);
+    static_assert(std::is_same_v<CompactStorage<int>,
+                                 detail::StorageByValue<int>>);
+#define CHECK1(Obj, cvref) \
+    static_assert(std::is_same_v<decltype(std::declval<CompactStorage< Obj > cvref>().object()), \
+                                 Obj cvref>);
+#define CHECK(cvref) \
+    CHECK1(empty, cvref) \
+    CHECK1(final, cvref) \
+    CHECK1(int, cvref) \
+    /* end */
+
+    FOR_EACH_CVREF(CHECK)
+#undef CHECK
+#undef CHECK1
+} // namespace _testing
+
+} // namespace QtPrivate
+
+#undef FOR_EACH_CVREF
+
+QT_END_NAMESPACE