Use of deleted function error when compiling

[Poldi]

The following code does not compile as the compiler deletes the client decalartion because the default definition would be ill-formed

Client Header

#ifndef CLIENT_H
#define CLIENT_H

#include <QObject>

class Client : public QObject
{
     Q_OBJECT
public:
    explicit Client(QObject *parent = nullptr);

signals:

};

#endif // CLIENT_H

Client Manager Header

#ifndef CLIENTMANAGER_H
#define CLIENTMANAGER_H

#include <QObject>
#include <QTcpSocket>
#include <QVector>
#include "networkremote/client.h"

class ClientManager : public QObject
{
     Q_OBJECT
public:
    explicit ClientManager(QObject *parent = nullptr);
    ~ClientManager();
    void AddClient(QTcpSocket *socket);
    void RemoveClient(QTcpSocket *socket);

private:
  QVector<Client> clients_;
  Client *client_ = nullptr;
  QTcpSocket *socket_ = nullptr;
};

#endif // CLIENTMANAGER_H

Client Manager

#include "clientmanager.h"

ClientManager::ClientManager(QObject *parent)
    : QObject{parent}
{
}

ClientManager::~ClientManager()
{}

void ClientManager::AddClient(QTcpSocket *socket)
{
  socket_ = socket;
  client_ = new Client;
  clients_.append(*client_);
}

Copy of the log

15:07:38: Running steps for project strawberry...
15:07:38: Starting: "/home/llist/Qt/Tools/CMake/bin/cmake" --build /home/llist/sec1/git/build-myStrawberry-Desktop_Qt_6_6_1_GCC_64bit-Debug --target all
[1/4 7.1/sec] Generating /home/llist/sec1/git/myStrawberry/src/translations/translations.pot
[2/4 1.8/sec] Building CXX object src/CMakeFiles/strawberry_lib.dir/networkremote/clientmanager.cpp.o
FAILED: src/CMakeFiles/strawberry_lib.dir/networkremote/clientmanager.cpp.o 
/usr/bin/ccache /usr/bin/x86_64-linux-gnu-g++ -DBOOST_BIND_NO_PLACEHOLDERS -DKDSINGLEAPPLICATION_STATIC_BUILD -DQT_CONCURRENT_LIB -DQT_CORE_LIB -DQT_DBUS_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_NO_CAST_FROM_BYTEARRAY -DQT_NO_CAST_TO_ASCII -DQT_NO_FOREACH -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -DQT_NO_URL_CAST_FROM_STRING -DQT_SQL_LIB -DQT_STRICT_ITERATORS -DQT_USE_QSTRINGBUILDER -DQT_WIDGETS_LIB -I/home/llist/sec1/git/myStrawberry -I/home/llist/sec1/git/build-myStrawberry-Desktop_Qt_6_6_1_GCC_64bit-Debug -I/home/llist/sec1/git/build-myStrawberry-Desktop_Qt_6_6_1_GCC_64bit-Debug/src -I/home/llist/sec1/git/myStrawberry/src -I/home/llist/sec1/git/myStrawberry/ext/libstrawberry-common -I/home/llist/sec1/git/myStrawberry/ext/libstrawberry-tagreader -I/home/llist/sec1/git/build-myStrawberry-Desktop_Qt_6_6_1_GCC_64bit-Debug/ext/libstrawberry-tagreader -I/home/llist/sec1/git/myStrawberry/3rdparty/kdsingleapplication/KDSingleApplication/src -I/home/llist/sec1/git/myStrawberry/3rdparty/kdsingleapplication -isystem /usr/include/glib-2.0 -isystem /usr/lib/x86_64-linux-gnu/glib-2.0/include -isystem /usr/include/gstreamer-1.0 -isystem /usr/include/orc-0.4 -isystem /usr/include/libmount -isystem /usr/include/blkid -isystem /usr/include/gio-unix-2.0 -isystem /usr/include/gpod-1.0 -isystem /usr/include/gdk-pixbuf-2.0 -isystem /usr/include/libpng16 -isystem /usr/include/libusb-1.0 -isystem /home/llist/Qt/6.6.1/gcc_64/include/QtCore -isystem /home/llist/Qt/6.6.1/gcc_64/include -isystem /home/llist/Qt/6.6.1/gcc_64/mkspecs/linux-g++ -isystem /home/llist/Qt/6.6.1/gcc_64/include/QtConcurrent -isystem /home/llist/Qt/6.6.1/gcc_64/include/QtGui -isystem /home/llist/Qt/6.6.1/gcc_64/include/QtWidgets -isystem /home/llist/Qt/6.6.1/gcc_64/include/QtNetwork -isystem /home/llist/Qt/6.6.1/gcc_64/include/QtSql -isystem /home/llist/Qt/6.6.1/gcc_64/include/QtDBus -DQT_QML_DEBUG -g -std=gnu++17 -fdiagnostics-color=always -std=c++17 -Wall -Wextra -Wpedantic -Wunused -Wshadow -Wundef -Wuninitialized -Wredundant-decls -Wcast-align -Winit-self -Wmissing-include-dirs -Wmissing-declarations -Wstrict-overflow=2 -Wunused-parameter -Wformat=2 -Wdisabled-optimization -Woverloaded-virtual -Wold-style-cast -fPIC -MD -MT src/CMakeFiles/strawberry_lib.dir/networkremote/clientmanager.cpp.o -MF src/CMakeFiles/strawberry_lib.dir/networkremote/clientmanager.cpp.o.d -o src/CMakeFiles/strawberry_lib.dir/networkremote/clientmanager.cpp.o -c /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp
/home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp: In member function ‘void ClientManager::RemoveClient(QTcpSocket*)’:
/home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:23:46: warning: unused parameter ‘socket’ [-Wunused-parameter]
   23 | void ClientManager::RemoveClient(QTcpSocket *socket)
      |                                  ~~~~~~~~~~~~^~~~~~
In file included from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydatapointer.h:7,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qbytearray.h:11,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qstringview.h:8,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qchar.h:656,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qstring.h:14,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobject.h:11,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/QObject:1,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.h:4,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:1:
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h: In instantiation of ‘void QtPrivate::QGenericArrayOps<T>::emplace(qsizetype, Args&& ...) [with Args = {const Client&}; T = Client; qsizetype = long long int]’:
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:877:15:   required from ‘T& QList<T>::emplaceBack(Args&& ...) [with Args = {const Client&}; T = Client; QList<T>::reference = Client&]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:441:48:   required from ‘void QList<T>::append(QList<T>::parameter_type) [with T = Client; QList<T>::parameter_type = const Client&]’
/home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:17:18:   required from here
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h:581:17: error: use of deleted function ‘Client::Client(const Client&)’
  581 |                 new (this->end()) T(std::forward<Args>(args)...);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.h:7,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:1:
/home/llist/sec1/git/myStrawberry/src/networkremote/client.h:6:7: note: ‘Client::Client(const Client&)’ is implicitly deleted because the default definition would be ill-formed:
    6 | class Client : public QObject
      |       ^~~~~~
/home/llist/sec1/git/myStrawberry/src/networkremote/client.h:6:7: error: use of deleted function ‘QObject::QObject(const QObject&)’
In file included from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qglobal.h:43,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qnamespace.h:12,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobjectdefs.h:12,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobject.h:10,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/QObject:1,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.h:4,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:1:
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobject.h:353:5: note: declared here
  353 |     Q_DISABLE_COPY(QObject)
      |     ^~~~~~~~~~~~~~
In file included from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydatapointer.h:7,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qbytearray.h:11,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qstringview.h:8,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qchar.h:656,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qstring.h:14,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobject.h:11,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/QObject:1,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.h:4,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:1:
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h:586:17: error: use of deleted function ‘Client::Client(const Client&)’
  586 |                 new (this->begin() - 1) T(std::forward<Args>(args)...);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h:592:11: error: use of deleted function ‘Client::Client(const Client&)’
  592 |         T tmp(std::forward<Args>(args)...);
      |           ^~~
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h:600:13: error: use of deleted function ‘Client::Client(Client&&)’
  600 |             new (this->begin() - 1) T(std::move(tmp));
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.h:7,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:1:
/home/llist/sec1/git/myStrawberry/src/networkremote/client.h:6:7: note: ‘Client::Client(Client&&)’ is implicitly deleted because the default definition would be ill-formed:
    6 | class Client : public QObject
      |       ^~~~~~
/home/llist/sec1/git/myStrawberry/src/networkremote/client.h:6:7: error: use of deleted function ‘QObject::QObject(const QObject&)’
In file included from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qglobal.h:43,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qnamespace.h:12,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobjectdefs.h:12,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobject.h:10,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/QObject:1,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.h:4,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:1:
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobject.h:353:5: note: declared here
  353 |     Q_DISABLE_COPY(QObject)
      |     ^~~~~~~~~~~~~~
In file included from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydatapointer.h:7,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qbytearray.h:11,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qstringview.h:8,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qchar.h:656,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qstring.h:14,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/qobject.h:11,
                 from /home/llist/Qt/6.6.1/gcc_64/include/QtCore/QObject:1,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.h:4,
                 from /home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:1:
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h: In instantiation of ‘void QtPrivate::QGenericArrayOps<T>::copyAppend(const T*, const T*) [with T = Client]’:
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydatapointer.h:235:31:   required from ‘void QArrayDataPointer<T>::reallocateAndGrow(QArrayData::GrowthPosition, qsizetype, QArrayDataPointer<T>*) [with T = Client; qsizetype = long long int]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydatapointer.h:139:13:   required from ‘void QArrayDataPointer<T>::detach(QArrayDataPointer<T>*) [with T = Client]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:409:29:   required from ‘void QList<T>::detach() [with T = Client]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:609:22:   required from ‘QList<T>::iterator QList<T>::end() [with T = Client]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:878:17:   required from ‘T& QList<T>::emplaceBack(Args&& ...) [with Args = {const Client&}; T = Client; QList<T>::reference = Client&]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:441:48:   required from ‘void QList<T>::append(QList<T>::parameter_type) [with T = Client; QList<T>::parameter_type = const Client&]’
/home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:17:18:   required from here
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h:341:13: error: use of deleted function ‘Client::Client(const Client&)’
  341 |             new (data + this->size) T(*b);
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h: In instantiation of ‘void QtPrivate::QGenericArrayOps<T>::moveAppend(T*, T*) [with T = Client]’:
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydatapointer.h:237:31:   required from ‘void QArrayDataPointer<T>::reallocateAndGrow(QArrayData::GrowthPosition, qsizetype, QArrayDataPointer<T>*) [with T = Client; qsizetype = long long int]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydatapointer.h:139:13:   required from ‘void QArrayDataPointer<T>::detach(QArrayDataPointer<T>*) [with T = Client]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:409:29:   required from ‘void QList<T>::detach() [with T = Client]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:609:22:   required from ‘QList<T>::iterator QList<T>::end() [with T = Client]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:878:17:   required from ‘T& QList<T>::emplaceBack(Args&& ...) [with Args = {const Client&}; T = Client; QList<T>::reference = Client&]’
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qlist.h:441:48:   required from ‘void QList<T>::append(QList<T>::parameter_type) [with T = Client; QList<T>::parameter_type = const Client&]’
/home/llist/sec1/git/myStrawberry/src/networkremote/clientmanager.cpp:17:18:   required from here
/home/llist/Qt/6.6.1/gcc_64/include/QtCore/qarraydataops.h:373:13: error: use of deleted function ‘Client::Client(Client&&)’
  373 |             new (data + this->size) T(std::move(*b));
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ninja: build stopped: subcommand failed.
15:07:39: The process "/home/llist/Qt/Tools/CMake/bin/cmake" exited with code 1.
Error while building/deploying project strawberry (kit: Desktop Qt 6.6.1 GCC 64bit)
When executing step "Build"
15:07:39: Elapsed time: 00:01.

Thanks

[ChrisW67]

@Poldi said in Use of deleted function error when compiling:

The following code does not compile as the compiler deletes the client decalartion because the default definition would be ill-formed

clients_ needs to be an array of pointers not objects.
You cannot copy a QObject by design.

The copy constructor is disabled by the:

353 |     Q_DISABLE_COPY(QObject)

line you see in the error output.

[Poldi]

@ChrisW67 Thanks