Move q20::remove_cvref to q20type_traits.h

The original is defined in <type_traits>, not <functional>.

Pick-to: 6.5
Change-Id: I596e56f64d2eed609ad2f7e6f03ae006afaa2fa9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

5 files changed, 46 insertions, 15 deletions

diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index 32a6d65ece..b468687da5 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -104,6 +104,7 @@ qt_internal_add_module(Core
         global/q20algorithm.h
         global/q20functional.h
         global/q20iterator.h
+        global/q20type_traits.h
         global/q23functional.h
         global/qxpfunctional.h
         global/qxptype_traits.h
diff --git a/src/corelib/global/q20functional.h b/src/corelib/global/q20functional.h
index 7ba10bd4b1..a39b4fceb3 100644
--- a/src/corelib/global/q20functional.h
+++ b/src/corelib/global/q20functional.h
@@ -41,19 +41,6 @@ struct identity
 #endif // __cpp_lib_ranges
 } // namespace q20
 
-namespace q20 {
-// like std::remove_cvref(_t)
-#ifdef __cpp_lib_remove_cvref
-using std::remove_cvref;
-using std::remove_cvref_t;
-#else
-template <typename T>
-struct remove_cvref : std::remove_cv<std::remove_reference_t<T>> {};
-template <typename T>
-using remove_cvref_t = std::remove_cv_t<std::remove_reference_t<T>>;
-#endif // __cpp_lib_remove_cvref
-}
-
 QT_END_NAMESPACE
 
 #endif /* Q20FUNCTIONAL_H */
diff --git a/src/corelib/global/q20type_traits.h b/src/corelib/global/q20type_traits.h
new file mode 100644
index 0000000000..2e812ed39c
--- /dev/null
+++ b/src/corelib/global/q20type_traits.h
@@ -0,0 +1,43 @@
+// Copyright (C) 2021 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+#ifndef Q20TYPE_TRAITS_H
+#define Q20TYPE_TRAITS_H
+
+#include <QtCore/qtconfigmacros.h>
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API. Types and functions defined in this
+// file can reliably be replaced by their std counterparts, once available.
+// You may use these definitions in your own code, but be aware that we
+// will remove them once Qt depends on the C++ version that supports
+// them in namespace std. There will be NO deprecation warning, the
+// definitions will JUST go away.
+//
+// If you can't agree to these terms, don't use these definitions!
+//
+// We mean it.
+//
+
+#include <type_traits>
+
+QT_BEGIN_NAMESPACE
+
+namespace q20 {
+// like std::remove_cvref(_t)
+#ifdef __cpp_lib_remove_cvref
+using std::remove_cvref;
+using std::remove_cvref_t;
+#else
+template <typename T>
+using remove_cvref = std::remove_cv<std::remove_reference_t<T>>;
+template <typename T>
+using remove_cvref_t = std::remove_cv_t<std::remove_reference_t<T>>;
+#endif // __cpp_lib_remove_cvref
+}
+
+QT_END_NAMESPACE
+
+#endif /* Q20TYPE_TRAITS_H */
diff --git a/src/corelib/global/qxpfunctional.h b/src/corelib/global/qxpfunctional.h
index 9657059753..abe00087ad 100644
--- a/src/corelib/global/qxpfunctional.h
+++ b/src/corelib/global/qxpfunctional.h
@@ -22,7 +22,7 @@
 //
 
 #include <QtCore/q23functional.h>
-#include <type_traits>
+#include <QtCore/q20type_traits.h>
 #include <utility>
 
 QT_BEGIN_NAMESPACE
diff --git a/src/corelib/text/qanystringview.h b/src/corelib/text/qanystringview.h
index a3117a4b79..6bf301cfd2 100644
--- a/src/corelib/text/qanystringview.h
+++ b/src/corelib/text/qanystringview.h
@@ -11,7 +11,7 @@
 #ifdef __cpp_impl_three_way_comparison
 #include <compare>
 #endif
-#include <QtCore/q20functional.h>
+#include <QtCore/q20type_traits.h>
 #include <limits>
 
 class tst_QAnyStringView;