On Wednesday 21 August 2024 14:16:50 CEST Halla Rempt wrote:
> 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?
The error has nothing to do with categorised logging, but is due to
`kis_debug.h` redefining `QT_ASSERT()`. The change that happened is that Qt 6
at some point added a `QT_ASSERT()` check to `QVector2D::operator/()` which is
marked as `inline constexpr`. This works fine with Qt's version of
`QT_ASSERT()` but your version adds logging which calls into non-constexpr
functions which is not allowed in a constexpr function. Due to the inlining,
the compiler uses whatever declaration that can be found at the callsite for
the macro.
I don't think there is a way to make categorised logging work in a constexpr
context. Personally I would recommend to not redefine macros like that and
instead use a separate macro if you want one with logging.
- Arjen
>
> 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__)
