Another porting question -- QLoggingCategory

[Halla Rempt]

Hi,

We had setup logging in Krita as follows:

kis_debug.h:

extern const KRITAGLOBAL_EXPORT QLoggingCategory &_30009();
extern const KRITAGLOBAL_EXPORT QLoggingCategory &_41000();
extern const KRITAGLOBAL_EXPORT QLoggingCategory &_41001();
...
#define dbgResources qCDebug(_30009)
#define dbgKrita qCDebug(_41000)
#define dbgImage qCDebug(_41001)
...
#define infoResources qCInfo(_30009)
#define infoKrita qCInfo(_41000)
#define infoImage qCInfo(_41001)

kis_debug.cpp

Q_LOGGING_CATEGORY(_30009, "krita.lib.resources", QtInfoMsg)
Q_LOGGING_CATEGORY(_41000, "krita.general", QtInfoMsg)
Q_LOGGING_CATEGORY(_41001, "krita.core", QtInfoMsg)

And we'd use this like:

dbgResources << "Skipping saving tag " << tag->name(false) << filename << tag->resourceType();

This works fine with Qt5, but with Q6 we get errors:


n file included from /usr/include/x86_64-linux-gnu/qt6/QtCore/QLoggingCategory:1,
                 from /home/halla/dev/krita/libs/global/kis_debug.h:10,
                 from /home/halla/dev/krita/libs/global/kis_algebra_2d.cpp:11:
/usr/include/x86_64-linux-gnu/qt6/QtGui/qvectornd.h: In function ‘constexpr QVector2D operator/(QVector2D, float)’:
/home/halla/dev/krita/libs/global/kis_debug.h:102:18: error: variable ‘qt_category’ of non-literal type ‘{anonymous}::QLoggingCategoryMacroHolder<QtCriticalMsg>’ in ‘constexpr’ function
  102 | #define errKrita qCCritical(_41000)
      |                  ^~~~~~~~~~
/usr/include/x86_64-linux-gnu/qt6/QtCore/qloggingcategory.h:60:35: note: ‘{anonymous}::QLoggingCategoryMacroHolder<QtCriticalMsg>’ is not literal because:
   60 | template <QtMsgType Which> struct QLoggingCategoryMacroHolder
      |                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~


The Qt code changed from 

#if !defined(QT_NO_DEBUG_OUTPUT)
#  define qCDebug(category, ...) \
    for (bool qt_category_enabled = category().isDebugEnabled(); qt_category_enabled; qt_category_enabled = false) \
        QMessageLogger(QT_MESSAGELOG_FILE, QT_MESSAGELOG_LINE, QT_MESSAGELOG_FUNC, category().categoryName()).debug(__VA_ARGS__)
#else
#  define qCDebug(category, ...) QT_NO_QDEBUG_MACRO()
#endif

in Qt5 to 

#define QT_MESSAGE_LOGGER_COMMON(category, level) \
    for (QLoggingCategoryMacroHolder<level> qt_category((category)()); qt_category; qt_category.control = false) \
        QMessageLogger(QT_MESSAGELOG_FILE, QT_MESSAGELOG_LINE, QT_MESSAGELOG_FUNC, qt_category.name())

#define qCDebug(category, ...) QT_MESSAGE_LOGGER_COMMON(category, QtDebugMsg).debug(__VA_ARGS__)

And I cannot figure out how to avoid that error other than replacing all our defines with literal calls to qCDebug(), which is going to be a huge diff.

Does anyone have any idea?

Halla




#define QT_MESSAGE_LOGGER_COMMON(category, level) \
    for (QLoggingCategoryMacroHolder<level> qt_category((category)()); qt_category; qt_category.control = false) \
        QMessageLogger(QT_MESSAGELOG_FILE, QT_MESSAGELOG_LINE, QT_MESSAGELOG_FUNC, qt_category.name())

#define qCDebug(category, ...) QT_MESSAGE_LOGGER_COMMON(category, QtDebugMsg).debug(__VA_ARGS__)