Qt6 porting, undefined symbol: _ZN10EngineBase16staticMetaObjectEHi

[JonB]

@sebaro said in Qt6 porting, undefined symbol: _ZN10EngineBase16staticMetaObjectEHi:

I clean it after each code change

And precisely what does that mean? I suggested you delete the build output directory. If something like make clean that may not be good enough. Just saying, up to you.

[sebaro]

@JonB

I delete the content of build directory, I don't use make clean. Every cmake/make is with an empty build directory.

[JonB]

@sebaro Fair enough.

[Christian Ehrlicher]

Simplify your testcase until you find the bug or you can post it here.

[sierdzio]

@sebaro you are not running moc anywhere, so meta object information is not generated.

In your cmake files, add this:

set(CMAKE_AUTOMOC ON)

[sebaro]

Automoc was set to true, added CMAKE_AUTOMOC:

set(CMAKE_AUTOMOC ON)
qt_standard_project_setup()
SET_TARGET_PROPERTIES(enginempv PROPERTIES AUTOMOC TRUE)

It's in the build progress "Automatic MOC and UIC":

[ 98%] Built target enginempv_autogen_timestamp_deps
[ 98%] Automatic MOC and UIC for target enginempv
[ 98%] Built target enginempv_autogen
[ 99%] Building CXX object src/core/player/mpv/CMakeFiles/enginempv.dir/engine_mpv.cpp.o
[ 99%] Building CXX object src/core/player/mpv/CMakeFiles/enginempv.dir/enginempv_autogen/mocs_compilation.cpp.o
[100%] Linking CXX shared library ../../../../lib/libenginempv.so
[100%] Built target enginempv

c++filt _ZN10EngineBase16staticMetaObjectE
EngineBase::staticMetaObject

I see the moc files are generated and they contain EngineBase::staticMetaObject:

moc_engine_base.cpp

/****************************************************************************
** Meta object code from reading C++ file 'engine_base.h'
**
** Created by: The Qt Meta Object Compiler version 68 (Qt 6.7.0)
**
** WARNING! All changes made in this file will be lost!
*****************************************************************************/

#include "../../../src/core/player/engine_base.h"
#include <QtCore/qmetatype.h>

#include <QtCore/qtmochelpers.h>

#include <memory>


#include <QtCore/qxptype_traits.h>
#if !defined(Q_MOC_OUTPUT_REVISION)
#error "The header file 'engine_base.h' doesn't include <QObject>."
#elif Q_MOC_OUTPUT_REVISION != 68
#error "This file was generated using the moc from 6.7.0. It"
#error "cannot be used with the include files from this version of Qt."
#error "(The moc has changed too much.)"
#endif

#ifndef Q_CONSTINIT
#define Q_CONSTINIT
#endif

QT_WARNING_PUSH
QT_WARNING_DISABLE_DEPRECATED
QT_WARNING_DISABLE_GCC("-Wuseless-cast")
namespace {

#ifdef QT_MOC_HAS_STRINGDATA
struct qt_meta_stringdata_CLASSEngineBaseENDCLASS_t {};
constexpr auto qt_meta_stringdata_CLASSEngineBaseENDCLASS = QtMocHelpers::stringData(
    "EngineBase",
    "mediaChanged",
    "",
    "mediaMetaDataChanged",
    "mediaAboutToFinish",
    "mediaFinished",
    "mediaTick",
    "time",
    "mediaTotalTimeChanged",
    "newTotalTime",
    "mediaSeekableChanged",
    "engineQueueFinished",
    "engineStateChanged",
    "engineRequestStop",
    "volumeChanged",
    "muteStateChanged",
    "volumeMute",
    "volumeInc",
    "volumeDec"
);
#else  // !QT_MOC_HAS_STRINGDATA
#error "qtmochelpers.h not found or too old."
#endif // !QT_MOC_HAS_STRINGDATA
} // unnamed namespace

Q_CONSTINIT static const uint qt_meta_data_CLASSEngineBaseENDCLASS[] = {

 // content:
      12,       // revision
       0,       // classname
       0,    0, // classinfo
      15,   14, // methods
       0,    0, // properties
       0,    0, // enums/sets
       0,    0, // constructors
       0,       // flags
      12,       // signalCount

 // signals: name, argc, parameters, tag, flags, initial metatype offsets
       1,    0,  104,    2, 0x06,    1 /* Public */,
       3,    0,  105,    2, 0x06,    2 /* Public */,
       4,    0,  106,    2, 0x06,    3 /* Public */,
       5,    0,  107,    2, 0x06,    4 /* Public */,
       6,    1,  108,    2, 0x06,    5 /* Public */,
       8,    1,  111,    2, 0x06,    7 /* Public */,
      10,    1,  114,    2, 0x06,    9 /* Public */,
      11,    0,  117,    2, 0x06,   11 /* Public */,
      12,    0,  118,    2, 0x06,   12 /* Public */,
      13,    0,  119,    2, 0x06,   13 /* Public */,
      14,    0,  120,    2, 0x06,   14 /* Public */,
      15,    0,  121,    2, 0x06,   15 /* Public */,

 // slots: name, argc, parameters, tag, flags, initial metatype offsets
      16,    0,  122,    2, 0x0a,   16 /* Public */,
      17,    0,  123,    2, 0x0a,   17 /* Public */,
      18,    0,  124,    2, 0x0a,   18 /* Public */,

 // signals: parameters
    QMetaType::Void,
    QMetaType::Void,
    QMetaType::Void,
    QMetaType::Void,
    QMetaType::Void, QMetaType::LongLong,    7,
    QMetaType::Void, QMetaType::LongLong,    9,
    QMetaType::Void, QMetaType::Bool,    2,
    QMetaType::Void,
    QMetaType::Void,
    QMetaType::Void,
    QMetaType::Void,
    QMetaType::Void,

 // slots: parameters
    QMetaType::Void,
    QMetaType::Void,
    QMetaType::Void,

       0        // eod
};

Q_CONSTINIT const QMetaObject EngineBase::staticMetaObject = { {
    QMetaObject::SuperData::link<QObject::staticMetaObject>(),
    qt_meta_stringdata_CLASSEngineBaseENDCLASS.offsetsAndSizes,
    qt_meta_data_CLASSEngineBaseENDCLASS,
    qt_static_metacall,
    nullptr,
    qt_incomplete_metaTypeArray<qt_meta_stringdata_CLASSEngineBaseENDCLASS_t,
        // Q_OBJECT / Q_GADGET
        QtPrivate::TypeAndForceComplete<EngineBase, std::true_type>,
        // method 'mediaChanged'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'mediaMetaDataChanged'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'mediaAboutToFinish'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'mediaFinished'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'mediaTick'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        QtPrivate::TypeAndForceComplete<qint64, std::false_type>,
        // method 'mediaTotalTimeChanged'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        QtPrivate::TypeAndForceComplete<qint64, std::false_type>,
        // method 'mediaSeekableChanged'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        QtPrivate::TypeAndForceComplete<bool, std::false_type>,
        // method 'engineQueueFinished'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'engineStateChanged'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'engineRequestStop'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'volumeChanged'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'muteStateChanged'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'volumeMute'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'volumeInc'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'volumeDec'
        QtPrivate::TypeAndForceComplete<void, std::false_type>
    >,
    nullptr
} };

void EngineBase::qt_static_metacall(QObject *_o, QMetaObject::Call _c, int _id, void **_a)
{
    if (_c == QMetaObject::InvokeMetaMethod) {
        auto *_t = static_cast<EngineBase *>(_o);
        (void)_t;
        switch (_id) {
        case 0: _t->mediaChanged(); break;
        case 1: _t->mediaMetaDataChanged(); break;
        case 2: _t->mediaAboutToFinish(); break;
        case 3: _t->mediaFinished(); break;
        case 4: _t->mediaTick((*reinterpret_cast< std::add_pointer_t<qint64>>(_a[1]))); break;
        case 5: _t->mediaTotalTimeChanged((*reinterpret_cast< std::add_pointer_t<qint64>>(_a[1]))); break;
        case 6: _t->mediaSeekableChanged((*reinterpret_cast< std::add_pointer_t<bool>>(_a[1]))); break;
        case 7: _t->engineQueueFinished(); break;
        case 8: _t->engineStateChanged(); break;
        case 9: _t->engineRequestStop(); break;
        case 10: _t->volumeChanged(); break;
        case 11: _t->muteStateChanged(); break;
        case 12: _t->volumeMute(); break;
        case 13: _t->volumeInc(); break;
        case 14: _t->volumeDec(); break;
        default: ;
        }
    } else if (_c == QMetaObject::IndexOfMethod) {
        int *result = reinterpret_cast<int *>(_a[0]);
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::mediaChanged; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 0;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::mediaMetaDataChanged; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 1;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::mediaAboutToFinish; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 2;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::mediaFinished; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 3;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)(qint64 );
            if (_t _q_method = &EngineBase::mediaTick; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 4;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)(qint64 );
            if (_t _q_method = &EngineBase::mediaTotalTimeChanged; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 5;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)(bool );
            if (_t _q_method = &EngineBase::mediaSeekableChanged; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 6;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::engineQueueFinished; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 7;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::engineStateChanged; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 8;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::engineRequestStop; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 9;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::volumeChanged; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 10;
                return;
            }
        }
        {
            using _t = void (EngineBase::*)();
            if (_t _q_method = &EngineBase::muteStateChanged; *reinterpret_cast<_t *>(_a[1]) == _q_method) {
                *result = 11;
                return;
            }
        }
    }
}

const QMetaObject *EngineBase::metaObject() const
{
    return QObject::d_ptr->metaObject ? QObject::d_ptr->dynamicMetaObject() : &staticMetaObject;
}

void *EngineBase::qt_metacast(const char *_clname)
{
    if (!_clname) return nullptr;
    if (!strcmp(_clname, qt_meta_stringdata_CLASSEngineBaseENDCLASS.stringdata0))
        return static_cast<void*>(this);
    return QObject::qt_metacast(_clname);
}

int EngineBase::qt_metacall(QMetaObject::Call _c, int _id, void **_a)
{
    _id = QObject::qt_metacall(_c, _id, _a);
    if (_id < 0)
        return _id;
    if (_c == QMetaObject::InvokeMetaMethod) {
        if (_id < 15)
            qt_static_metacall(this, _c, _id, _a);
        _id -= 15;
    } else if (_c == QMetaObject::RegisterMethodArgumentMetaType) {
        if (_id < 15)
            *reinterpret_cast<QMetaType *>(_a[0]) = QMetaType();
        _id -= 15;
    }
    return _id;
}

// SIGNAL 0
void EngineBase::mediaChanged()
{
    QMetaObject::activate(this, &staticMetaObject, 0, nullptr);
}

// SIGNAL 1
void EngineBase::mediaMetaDataChanged()
{
    QMetaObject::activate(this, &staticMetaObject, 1, nullptr);
}

// SIGNAL 2
void EngineBase::mediaAboutToFinish()
{
    QMetaObject::activate(this, &staticMetaObject, 2, nullptr);
}

// SIGNAL 3
void EngineBase::mediaFinished()
{
    QMetaObject::activate(this, &staticMetaObject, 3, nullptr);
}

// SIGNAL 4
void EngineBase::mediaTick(qint64 _t1)
{
    void *_a[] = { nullptr, const_cast<void*>(reinterpret_cast<const void*>(std::addressof(_t1))) };
    QMetaObject::activate(this, &staticMetaObject, 4, _a);
}

// SIGNAL 5
void EngineBase::mediaTotalTimeChanged(qint64 _t1)
{
    void *_a[] = { nullptr, const_cast<void*>(reinterpret_cast<const void*>(std::addressof(_t1))) };
    QMetaObject::activate(this, &staticMetaObject, 5, _a);
}

// SIGNAL 6
void EngineBase::mediaSeekableChanged(bool _t1)
{
    void *_a[] = { nullptr, const_cast<void*>(reinterpret_cast<const void*>(std::addressof(_t1))) };
    QMetaObject::activate(this, &staticMetaObject, 6, _a);
}

// SIGNAL 7
void EngineBase::engineQueueFinished()
{
    QMetaObject::activate(this, &staticMetaObject, 7, nullptr);
}

// SIGNAL 8
void EngineBase::engineStateChanged()
{
    QMetaObject::activate(this, &staticMetaObject, 8, nullptr);
}

// SIGNAL 9
void EngineBase::engineRequestStop()
{
    QMetaObject::activate(this, &staticMetaObject, 9, nullptr);
}

// SIGNAL 10
void EngineBase::volumeChanged()
{
    QMetaObject::activate(this, &staticMetaObject, 10, nullptr);
}

// SIGNAL 11
void EngineBase::muteStateChanged()
{
    QMetaObject::activate(this, &staticMetaObject, 11, nullptr);
}
QT_WARNING_POP

moc_engine_mpv.cpp

/****************************************************************************
** Meta object code from reading C++ file 'engine_mpv.h'
**
** Created by: The Qt Meta Object Compiler version 68 (Qt 6.7.0)
**
** WARNING! All changes made in this file will be lost!
*****************************************************************************/

#include "../../../../../../../src/core/player/mpv/engine_mpv.h"
#include <QtCore/qmetatype.h>
#include <QtCore/qplugin.h>

#include <QtCore/qtmochelpers.h>

#include <memory>


#include <QtCore/qxptype_traits.h>
#if !defined(Q_MOC_OUTPUT_REVISION)
#error "The header file 'engine_mpv.h' doesn't include <QObject>."
#elif Q_MOC_OUTPUT_REVISION != 68
#error "This file was generated using the moc from 6.7.0. It"
#error "cannot be used with the include files from this version of Qt."
#error "(The moc has changed too much.)"
#endif

#ifndef Q_CONSTINIT
#define Q_CONSTINIT
#endif

QT_WARNING_PUSH
QT_WARNING_DISABLE_DEPRECATED
QT_WARNING_DISABLE_GCC("-Wuseless-cast")
namespace {

#ifdef QT_MOC_HAS_STRINGDATA
struct qt_meta_stringdata_CLASSEngineMpvENDCLASS_t {};
constexpr auto qt_meta_stringdata_CLASSEngineMpvENDCLASS = QtMocHelpers::stringData(
    "EngineMpv",
    "volumeMute",
    "",
    "volumeInc",
    "volumeDec"
);
#else  // !QT_MOC_HAS_STRINGDATA
#error "qtmochelpers.h not found or too old."
#endif // !QT_MOC_HAS_STRINGDATA
} // unnamed namespace

Q_CONSTINIT static const uint qt_meta_data_CLASSEngineMpvENDCLASS[] = {

 // content:
      12,       // revision
       0,       // classname
       0,    0, // classinfo
       3,   14, // methods
       0,    0, // properties
       0,    0, // enums/sets
       0,    0, // constructors
       0,       // flags
       0,       // signalCount

 // slots: name, argc, parameters, tag, flags, initial metatype offsets
       1,    0,   32,    2, 0x0a,    1 /* Public */,
       3,    0,   33,    2, 0x0a,    2 /* Public */,
       4,    0,   34,    2, 0x0a,    3 /* Public */,

 // slots: parameters
    QMetaType::Void,
    QMetaType::Void,
    QMetaType::Void,

       0        // eod
};

Q_CONSTINIT const QMetaObject EngineMpv::staticMetaObject = { {
    QMetaObject::SuperData::link<EngineBase::staticMetaObject>(),
    qt_meta_stringdata_CLASSEngineMpvENDCLASS.offsetsAndSizes,
    qt_meta_data_CLASSEngineMpvENDCLASS,
    qt_static_metacall,
    nullptr,
    qt_incomplete_metaTypeArray<qt_meta_stringdata_CLASSEngineMpvENDCLASS_t,
        // Q_OBJECT / Q_GADGET
        QtPrivate::TypeAndForceComplete<EngineMpv, std::true_type>,
        // method 'volumeMute'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'volumeInc'
        QtPrivate::TypeAndForceComplete<void, std::false_type>,
        // method 'volumeDec'
        QtPrivate::TypeAndForceComplete<void, std::false_type>
    >,
    nullptr
} };

void EngineMpv::qt_static_metacall(QObject *_o, QMetaObject::Call _c, int _id, void **_a)
{
    if (_c == QMetaObject::InvokeMetaMethod) {
        auto *_t = static_cast<EngineMpv *>(_o);
        (void)_t;
        switch (_id) {
        case 0: _t->volumeMute(); break;
        case 1: _t->volumeInc(); break;
        case 2: _t->volumeDec(); break;
        default: ;
        }
    }
    (void)_a;
}

const QMetaObject *EngineMpv::metaObject() const
{
    return QObject::d_ptr->metaObject ? QObject::d_ptr->dynamicMetaObject() : &staticMetaObject;
}

void *EngineMpv::qt_metacast(const char *_clname)
{
    if (!_clname) return nullptr;
    if (!strcmp(_clname, qt_meta_stringdata_CLASSEngineMpvENDCLASS.stringdata0))
        return static_cast<void*>(this);
    if (!strcmp(_clname, "yarock.EngineBase/1.0"))
        return static_cast< EngineBase*>(this);
    return EngineBase::qt_metacast(_clname);
}

int EngineMpv::qt_metacall(QMetaObject::Call _c, int _id, void **_a)
{
    _id = EngineBase::qt_metacall(_c, _id, _a);
    if (_id < 0)
        return _id;
    if (_c == QMetaObject::InvokeMetaMethod) {
        if (_id < 3)
            qt_static_metacall(this, _c, _id, _a);
        _id -= 3;
    } else if (_c == QMetaObject::RegisterMethodArgumentMetaType) {
        if (_id < 3)
            *reinterpret_cast<QMetaType *>(_a[0]) = QMetaType();
        _id -= 3;
    }
    return _id;
}

#ifdef QT_MOC_EXPORT_PLUGIN_V2
static constexpr unsigned char qt_pluginMetaDataV2_EngineMpv[] = {
    0xbf, 
    // "IID"
    0x02,  0x69,  'E',  'n',  'g',  'i',  'n',  'e', 
    'M',  'p',  'v', 
    // "className"
    0x03,  0x69,  'E',  'n',  'g',  'i',  'n',  'e', 
    'M',  'p',  'v', 
    0xff, 
};
QT_MOC_EXPORT_PLUGIN_V2(EngineMpv, EngineMpv, qt_pluginMetaDataV2_EngineMpv)
#else
QT_PLUGIN_METADATA_SECTION
Q_CONSTINIT static constexpr unsigned char qt_pluginMetaData_EngineMpv[] = {
    'Q', 'T', 'M', 'E', 'T', 'A', 'D', 'A', 'T', 'A', ' ', '!',
    // metadata version, Qt version, architectural requirements
    0, QT_VERSION_MAJOR, QT_VERSION_MINOR, qPluginArchRequirements(),
    0xbf, 
    // "IID"
    0x02,  0x69,  'E',  'n',  'g',  'i',  'n',  'e', 
    'M',  'p',  'v', 
    // "className"
    0x03,  0x69,  'E',  'n',  'g',  'i',  'n',  'e', 
    'M',  'p',  'v', 
    0xff, 
};
QT_MOC_EXPORT_PLUGIN(EngineMpv, EngineMpv)
#endif  // QT_MOC_EXPORT_PLUGIN_V2

QT_WARNING_POP

[sierdzio]

@sebaro so, problem solved?

[sebaro]

@sierdzio
No

[sebaro]

This post is deleted!

[sebaro]

Changing to the previous minimum required version of cmake fixes this:

CMakeLists.txt

cmake_minimum_required(VERSION 2.8.6)
#cmake_minimum_required(VERSION 3.16)

src/core/player/mpv/CMakeLists.txt

cmake_minimum_required(VERSION 2.6)
#cmake_minimum_required(VERSION 3.16)

Seems to be this policy:
https://cmake.org/cmake/help/latest/policy/CMP0065.html

This fixed the issue with cmake 3.4+:

set_target_properties(yarock PROPERTIES ENABLE_EXPORTS TRUE)