From c5b083dd13f37a285d27f654abf8fa3709bac585 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Fri, 26 May 2023 12:51:59 +0200
Subject: [PATCH] Short live q20::iter_reference_t

Another building block for QSpan.

Task-number: QTBUG-108124
Change-Id: Ic7205ec693d953f6b054282380e87e79dead8816
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit e86e2752845ede635840851198c334f550fafb8f)
---
 src/corelib/global/q20iterator.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/corelib/global/q20iterator.h b/src/corelib/global/q20iterator.h
index 23b6406b64c..9ed4d69965f 100644
--- a/src/corelib/global/q20iterator.h
+++ b/src/corelib/global/q20iterator.h
@@ -39,6 +39,16 @@ namespace q20 {
 #endif
 } // namespace q20
 
+// like q20::iter_reference_t
+namespace q20 {
+#ifdef __cpp_lib_ranges
+    using std::iter_reference_t;
+#else
+    template <typename Dereferencable> // unconstrained (constraint requires concepts)
+    using iter_reference_t = decltype(*std::declval<Dereferencable&>());
+#endif // __cpp_lib_ranges
+} // namespace q20
+
 QT_END_NAMESPACE
 
 #endif /* Q20ITERATOR_H */