From 01d94760d8d34e51e1442682fc151747943c7e25 Mon Sep 17 00:00:00 2001
From: Fabian Kosmale <fabian.kosmale@qt.io>
Date: Tue, 21 Sep 2021 11:13:06 +0200
Subject: [PATCH] tst_qmetatype: Fix operator< detection for std::optional

Amends ca54b741d6edda24773137aacee229db31dd3585.
operator< is not constrained in MSVC's standard library, either.

Pick-to: 6.2
Fixes: QTBUG-96690
Change-Id: Ibcbb9e53a1f9e8b13786f6d8c01489c61d8d2d7f
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
---
 src/corelib/global/qtypeinfo.h                        | 2 ++
 tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/src/corelib/global/qtypeinfo.h b/src/corelib/global/qtypeinfo.h
index 2729217aabe..7759eff370b 100644
--- a/src/corelib/global/qtypeinfo.h
+++ b/src/corelib/global/qtypeinfo.h
@@ -311,6 +311,8 @@ 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> {};
 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 09a51258863..66040228b4f 100644
--- a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
+++ b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
@@ -130,7 +130,9 @@ static_assert(!QTypeTraits::has_operator_less_than_v<std::map<int, NoOperators>>
 
 // std::optional
 static_assert(QTypeTraits::has_operator_equal_v<std::optional<QString>>);
+static_assert(QTypeTraits::has_operator_less_than_v<std::optional<QString>>);
 static_assert(!QTypeTraits::has_operator_equal_v<std::optional<NoOperators>>);
+static_assert(!QTypeTraits::has_operator_less_than_v<std::optional<NoOperators>>);
 
 // nested types
 static_assert(QTypeTraits::has_operator_equal_v<Nested>);