From 889d40ebe2d9d0e92caea2749608720f7c088173 Mon Sep 17 00:00:00 2001 From: Giuseppe D'Angelo Date: Fri, 3 Jan 2020 17:18:02 +0100 Subject: Centralize the implementation of move assignment operators At the moment we have two main strategies for dealing with move assignment in Qt: 1) move-and-swap, used by "containers" (in the broad sense): containers, but also smart pointers and similar classes that can hold user-defined types; 2) pure swap, used by containers that hold only memory (e.g. QString, QByteArray, ...) as well as most implicitly shared datatypes. Given the fact that a move assignment operator's code is just boilerplate (whether it's move-and-swap or pure swap), provide two _strictly internal_ macros to help write them, and apply the macros across corelib and gui, porting away from the hand-rolled implementations. The rule of thumb when porting to the new macros is: * Try to stick to the existing code behavior, unless broken * if changing, then follow this checklist: * if the class does not have a move constructor => pure swap (but consider ADDING a move constructor, if possible!) * if the class does have a move constructor, try to follow the criteria above, namely: * if the class holds only memory, pure swap; * if the class may hold anything else but memory (file handles, etc.), then move and swap. Noteworthy details: * some operators planned to be removed in Qt 6 were not ported; * as drive-by, some move constructors were simplified to be using qExchange(); others were outright broken and got fixed; * some contained some more interesting code and were not touched. Change-Id: Idaab3489247dcbabb6df3fa1e5286b69e1d372e9 Reviewed-by: Allan Sandfeld Jensen --- src/corelib/tools/qhash.h | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) (limited to 'src/corelib/tools/qhash.h') diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h index 2b1b155efb..a1c1371e24 100644 --- a/src/corelib/tools/qhash.h +++ b/src/corelib/tools/qhash.h @@ -750,15 +750,7 @@ public: : d(std::exchange(other.d, nullptr)) { } - QHash &operator=(QHash &&other) noexcept(std::is_nothrow_destructible::value) - { - if (d != other.d) { - if (d && !d->ref.deref()) - delete d; - d = std::exchange(other.d, nullptr); - } - return *this; - } + QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QHash) #ifdef Q_QDOC template QHash(InputIterator f, InputIterator l); -- cgit v1.2.3