QFuture::const_iterator: use modernize comparisons

Replace class operators operator==(), operator!=() of
QFuture::const_iterator: to friend method comparesEqual() and
Q_DECLARE_EQUALITY_COMPARABLE macro.

Task-number: QTBUG-120304
Change-Id: Ifa264b83f4d5623db99820847ab9a800cca99be2
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

2 files changed, 10 insertions, 6 deletions

diff --git a/src/corelib/thread/qfuture.h b/src/corelib/thread/qfuture.h
index 5939a93780..3945df066a 100644
--- a/src/corelib/thread/qfuture.h
+++ b/src/corelib/thread/qfuture.h
@@ -183,8 +183,6 @@ QT_WARNING_POP
         { future = o.future; index = o.index; return *this; }
         inline const T &operator*() const { return future->d.resultReference(index); }
         inline const T *operator->() const { return future->d.resultPointer(index); }
-        inline bool operator!=(const const_iterator &other) const { return index != other.index; }
-        inline bool operator==(const const_iterator &o) const { return !operator!=(o); }
         inline const_iterator &operator++()
         { index = advanceIndex(index, 1); return *this; }
         inline const_iterator &operator--()
@@ -213,6 +211,12 @@ QT_WARNING_POP
         { return const_iterator(k.future, k.advanceIndex(k.index, j)); }
 
     private:
+        friend bool comparesEqual(const const_iterator &lhs, const const_iterator &rhs) noexcept
+        {
+            return lhs.index == rhs.index;
+        }
+        Q_DECLARE_EQUALITY_COMPARABLE(const_iterator)
+
         /*! \internal
 
             Advances the iterator index \a idx \a n steps, waits for the
diff --git a/src/corelib/thread/qfuture.qdoc b/src/corelib/thread/qfuture.qdoc
index 9eda766968..b278d39882 100644
--- a/src/corelib/thread/qfuture.qdoc
+++ b/src/corelib/thread/qfuture.qdoc
@@ -613,17 +613,17 @@
     Returns a pointer to the current result.
 */
 
-/*! \fn template <typename T> bool QFuture<T>::const_iterator::operator!=(const const_iterator &other) const
+/*! \fn template <typename T> bool QFuture<T>::const_iterator::operator!=(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to a different result than this iterator;
+    Returns \c true if \a lhs points to a different result than \a rhs iterator;
     otherwise returns \c false.
 
     \sa operator==()
 */
 
-/*! \fn template <typename T> bool QFuture<T>::const_iterator::operator==(const const_iterator &other) const
+/*! \fn template <typename T> bool QFuture<T>::const_iterator::operator==(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to the same result as this iterator;
+    Returns \c true if \a lhs points to the same result as \a rhs iterator;
     otherwise returns \c false.
 
     \sa operator!=()