Deprecate QtFuture::makeReadyFuture()

[ChangeLog][Deprecation Notice][QtCore] The QtFuture::makeReadyFuture()
method and all its specializations are deprecated since Qt 6.10.
The reason for the deprecation is that the method has a
makeReadyFuture(const QList<T> &) overload, which behaves differently
from all other overloads (including other non-const ref QList
overloads).
Use QtFuture::makeReadyVoidFuture() when you need a ready void QFuture,
or QtFuture::makeReadyValueFuture() when you need to propagate the
input type to the returned QFuture, or QtFuture::makeReadyRangeFuture()
when you need to create a multi-value future based on an input
container.

Fixes: QTBUG-109677
Change-Id: I55125269989df0a02840d5ddd5763ef5f1070df5
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/corelib/thread/qfuture.h

@@ -522,15 +522,18 @@ QFuture<std::variant<std::decay_t<Futures>...>> whenAny(Futures &&... futures);
 
 #endif // Q_QDOC
 
+#if QT_DEPRECATED_SINCE(6, 10)
 #if defined(Q_QDOC)
 static QFuture<void> makeReadyFuture()
 #else
 template<typename T = void>
+QT_DEPRECATED_VERSION_X(6, 10, "Use makeReadyVoidFuture() instead")
 static QFuture<T> makeReadyFuture()
 #endif
 {
     return makeReadyVoidFuture();
 }
+#endif // QT_DEPRECATED_SINCE(6, 10)
 
 } // namespace QtFuture
 

src/corelib/thread/qfuture.qdoc

@@ -973,6 +973,12 @@
 
     \since 6.1
     \overload
+    \deprecated [6.10] Use makeReadyValueFuture() instead
+
+    The QtFuture::makeReadyFuture() method should be avoided because it has an
+    inconsistent set of overloads. It will be deprecated in future Qt releases.
+    Use QtFuture::makeReadyVoidFuture(), QtFuture::makeReadyValueFuture() or
+    QtFuture::makeReadyRangeFuture() instead.
 
     Creates and returns a QFuture which already has a result \a value.
     The returned QFuture has a type of std::decay_t<T>, where T is not void.
@@ -992,6 +998,12 @@
 
     \since 6.1
     \overload
+    \deprecated [6.10] Use makeReadyVoidFuture() instead
+
+    The QtFuture::makeReadyFuture() method should be avoided because it has an
+    inconsistent set of overloads. It will be deprecated in future Qt releases.
+    Use QtFuture::makeReadyVoidFuture(), QtFuture::makeReadyValueFuture() or
+    QtFuture::makeReadyRangeFuture() instead.
 
     Creates and returns a void QFuture. Such QFuture can't store any result.
     One can use it to query the state of the computation.
@@ -1015,6 +1027,12 @@
 
     \since 6.1
     \overload
+    \deprecated [6.10] Use makeReadyRangeFuture() instead
+
+    The QtFuture::makeReadyFuture() method should be avoided because it has an
+    inconsistent set of overloads. It will be deprecated in future Qt releases.
+    Use QtFuture::makeReadyVoidFuture(), QtFuture::makeReadyValueFuture() or
+    QtFuture::makeReadyRangeFuture() instead.
 
     Creates and returns a QFuture which already has multiple results set from \a values.
 

src/corelib/thread/qfuture_impl.h

@@ -1009,7 +1009,9 @@ static QFuture<std::decay_t<T>> makeReadyValueFuture(T &&value)
 
 Q_CORE_EXPORT QFuture<void> makeReadyVoidFuture(); // implemented in qfutureinterface.cpp
 
+#if QT_DEPRECATED_SINCE(6, 10)
 template<typename T, typename = QtPrivate::EnableForNonVoid<T>>
+QT_DEPRECATED_VERSION_X(6, 10, "Use makeReadyValueFuture() instead")
 static QFuture<std::decay_t<T>> makeReadyFuture(T &&value)
 {
     return makeReadyValueFuture(std::forward<T>(value));
@@ -1019,10 +1021,12 @@ static QFuture<std::decay_t<T>> makeReadyFuture(T &&value)
 // uses makeReadyVoidFuture() and required QFuture<void> to be defined.
 
 template<typename T>
+QT_DEPRECATED_VERSION_X(6, 10, "Use makeReadyRangeFuture() instead")
 static QFuture<T> makeReadyFuture(const QList<T> &values)
 {
     return makeReadyRangeFuture(values);
 }
+#endif // QT_DEPRECATED_SINCE(6, 10)
 
 #ifndef QT_NO_EXCEPTIONS
 

tests/auto/corelib/thread/qfuture/tst_qfuture.cpp

@@ -4078,6 +4078,9 @@ void tst_QFuture::rejectPendingResultOverwrite()
 
 void tst_QFuture::createReadyFutures()
 {
+#if QT_DEPRECATED_SINCE(6, 10)
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_DEPRECATED
     // using const T &
     {
         const int val = 42;
@@ -4113,6 +4116,8 @@ void tst_QFuture::createReadyFutures()
         QCOMPARE(f.resultCount(), 3);
         QCOMPARE(f.results(), values);
     }
+QT_WARNING_POP
+#endif // QT_DEPRECATED_SINCE(6, 10)
 
     // test makeReadyValueFuture<T>()
     {