From 687415e10cd7de8018410407ad0e25cf691c0d7f Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Mon, 31 Jul 2023 10:03:36 -0700
Subject: [PATCH] QMetaType: fix recursive detection of std::optional operators

Commit ca54b741d6edda24773137aacee229db31dd3585 used the internal
has_operator_equal (and commit 01d94760d8d34e51e1442682fc151747943c7e25
copied that for has_operator_less_than) instead of using the recursive
expander that was being used here. That assumed that the contained type
in std::optional would always be the last final check, which is an
incorrect assumption.

Fixes: QTBUG-115646
Change-Id: Ifbf974a4d10745b099b1fffd177702934bec27ff
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit cff13c2417225fcb5e2cca4c9a045bfe49c1034c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/global/qtypeinfo.h                |  4 ++--
 .../kernel/qmetatype/tst_qmetatype.cpp        | 20 +++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/corelib/global/qtypeinfo.h b/src/corelib/global/qtypeinfo.h
index e6d63241bbe..f89bf72635e 100644
--- a/src/corelib/global/qtypeinfo.h
+++ b/src/corelib/global/qtypeinfo.h
@@ -237,7 +237,7 @@ using expand_operator_equal_recursive = std::conjunction<expand_operator_equal<T
 template<typename T>
 struct expand_operator_equal_tuple : has_operator_equal<T> {};
 template<typename T>
-struct expand_operator_equal_tuple<std::optional<T>> : has_operator_equal<T> {};
+struct expand_operator_equal_tuple<std::optional<T>> : expand_operator_equal_recursive<T> {};
 template<typename T1, typename T2>
 struct expand_operator_equal_tuple<std::pair<T1, T2>> : expand_operator_equal_recursive<T1, T2> {};
 template<typename ...T>
@@ -277,7 +277,7 @@ using expand_operator_less_than_recursive = std::conjunction<expand_operator_les
 template<typename T>
 struct expand_operator_less_than_tuple : has_operator_less_than<T> {};
 template<typename T>
-struct expand_operator_less_than_tuple<std::optional<T>> : has_operator_less_than<T> {};
+struct expand_operator_less_than_tuple<std::optional<T>> : expand_operator_less_than_recursive<T> {};
 template<typename T1, typename T2>
 struct expand_operator_less_than_tuple<std::pair<T1, T2>> : expand_operator_less_than_recursive<T1, T2> {};
 template<typename ...T>
diff --git a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
index 61ea16c4da0..606a32dd4df 100644
--- a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
+++ b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
@@ -123,6 +123,26 @@ static_assert(!QTypeTraits::has_operator_less_than_v<std::tuple<int, Nested2>>);
 static_assert(QTypeTraits::has_operator_equal_v<std::tuple<int, Nested2>>);
 static_assert(!QTypeTraits::has_operator_less_than_v<std::tuple<int, Nested2>>);
 
+// optionals of nesteds
+static_assert(QTypeTraits::has_operator_equal_v<std::optional<std::variant<QString>>>);
+static_assert(QTypeTraits::has_operator_less_than_v<std::optional<std::variant<QString>>>);
+static_assert(!QTypeTraits::has_operator_equal_v<std::optional<std::variant<NoOperators>>>);
+static_assert(!QTypeTraits::has_operator_less_than_v<std::optional<std::variant<NoOperators>>>);
+
+static_assert(QTypeTraits::has_operator_equal_v<std::optional<Nested>>);
+static_assert(!QTypeTraits::has_operator_less_than_v<std::optional<Nested>>);
+static_assert(QTypeTraits::has_operator_equal_v<std::optional<std::tuple<int, Nested>>>);
+static_assert(!QTypeTraits::has_operator_less_than_v<std::optional<std::tuple<int, Nested>>>);
+static_assert(QTypeTraits::has_operator_equal_v<std::optional<std::tuple<int, Nested>>>);
+static_assert(!QTypeTraits::has_operator_less_than_v<std::optional<std::tuple<int, Nested>>>);
+
+static_assert(QTypeTraits::has_operator_equal_v<std::optional<Nested2>>);
+static_assert(!QTypeTraits::has_operator_less_than_v<std::optional<Nested2>>);
+static_assert(QTypeTraits::has_operator_equal_v<std::optional<std::tuple<int, Nested2>>>);
+static_assert(!QTypeTraits::has_operator_less_than_v<std::optional<std::tuple<int, Nested2>>>);
+static_assert(QTypeTraits::has_operator_equal_v<std::optional<std::tuple<int, Nested2>>>);
+static_assert(!QTypeTraits::has_operator_less_than_v<std::optional<std::tuple<int, Nested2>>>);
+
 }
 
 struct BaseGenericType