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| -rw-r--r-- | src/corelib/doc/src/qt6-changes.qdoc | 44 |
1 files changed, 40 insertions, 4 deletions
diff --git a/src/corelib/doc/src/qt6-changes.qdoc b/src/corelib/doc/src/qt6-changes.qdoc index 6354737249..dd4e7b54e2 100644 --- a/src/corelib/doc/src/qt6-changes.qdoc +++ b/src/corelib/doc/src/qt6-changes.qdoc @@ -395,11 +395,47 @@ \section1 QFuture and Related Classes - \section2 QFuture and QFutureWatcher + \section2 QFuture - In Qt 6, there are no changes that introduce source compatibility breaks - in code that was using QFuture and QFutureWatcher classes. However there - were some improvements which caused the following behavioral changes: + To avoid unintended usage of QFuture, there were some changes to + QFuture API in Qt 6, which may introduce source compatibility breaks. + + \section3 Implicit conversions between QFuture and other types + + Conversion of \c QFuture<T> to \c T has been disabled. The casting + operator was calling QFuture::result(), which may lead to undefined + behavior if the user has moved the results from QFuture via + QFuture::takeResult() before trying to do the conversion. Use + QFuture::result() or QFuture::takeResult() methods explicitly, + where you need to convert \c QFuture<T> to \c T. + + The implicit conversion from \c QFuture<T> to \c QFuture<void> has + been also disabled. If you really intend to do the conversion, use the + explicit \c {QFuture<void>(const QFuture<T> &)} constructor: + + \code + QFuture<int> future = ... + QFuture<void> voidFuture = QFuture<void>(future); + \endcode + + \section3 Equality operators + + The equality operators of QFuture have been removed. They were comparing + the underlying d-pointers instead of comparing the results, which is not + what users might expect. If you need to compare QFuture objects, use + \c QFuture::result() or \c QFuture::takeResult() methods. For example: + + \code + QFuture<int> future1 = ...; + QFuture<int> future2 = ...; + if (future1.result() == future2.result()) + // ... + \endcode + + \section2 Behavioral Changes to QFuture and QFutureWatcher + + In Qt 6, there were some improvements to QFuture and QFutureWatcher which + caused the following behavioral changes: \list |