Deprecate qAsConst()

std::as_const() is a 100% equivalent replacement.

[ChangeLog][Deprecation Notices][QtCore] qAsConst() is now
deprecated. You can simply globally search and replace "qAsConst" with
"std::as_const" in your code-base.

Change-Id: If9b29f9b4119cf5bdb9f0a1ada1271c6bb503916
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/corelib/global/qttypetraits.h

@@ -5,6 +5,7 @@
 #define QTTYPETRAITS_H
 
 #include <QtCore/qtconfigmacros.h>
+#include <QtCore/qtdeprecationmarkers.h>
 
 #include <type_traits>
 #include <utility>
@@ -24,14 +25,17 @@ constexpr std::underlying_type_t<Enum> qToUnderlying(Enum e) noexcept
 }
 
 #ifndef QT_NO_AS_CONST
+#if QT_DEPRECATED_SINCE(6, 6)
 
 // this adds const to non-const objects (like std::as_const)
 template <typename T>
+QT_DEPRECATED_VERSION_X_6_6("Use std::as_const() instead.")
 constexpr typename std::add_const<T>::type &qAsConst(T &t) noexcept { return t; }
 // prevent rvalue arguments:
 template <typename T>
 void qAsConst(const T &&) = delete;
 
+#endif // QT_DEPRECATED_SINCE(6, 6)
 #endif // QT_NO_AS_CONST
 
 #ifndef QT_NO_QEXCHANGE

src/corelib/global/qttypetraits.qdoc

@@ -15,6 +15,8 @@
     \relates <QtTypeTraits>
     \since 5.7
 
+    \deprecated [6.6] Use std::as_const() instead.
+
     Returns \a t cast to \c{const T}.
 
     This function is a Qt implementation of C++17's std::as_const(),
@@ -52,6 +54,8 @@
     \since 5.7
     \overload
 
+    \deprecated [6.6]
+
     This overload is deleted to prevent a dangling reference in code like
     \snippet code/src_corelib_global_qglobal.cpp as-const-4
 */