Re: [Interest] can't dump QStringList with qDebug()
On Tuesday, 7 March 2023 21:20:02 PST Hamish Moffatt via Interest wrote: > I confirm that my test code compiles in 6.5.0-beta3. And I can reproduce the error with GCC 13 if I check out the 6.4.2 headers. GCC 13 says: note: candidate: ‘template QDebugIfHasDebugStreamContainer, T> operator<<(QDebug, const QList&)’ note: template argument deduction/substitution failed qdebug.h:217:53: required by substitution of ‘template QDebugIfHasDebugStreamContainer, T> operator<<(QDebug, const QList&) [with T = QString]’ type_traits:2594:11: error: no type named ‘type’ in ‘struct std::enable_if’ This is GCC speak for "condition evaluated to false" By moving the constraint from the return type to a static_assert inside the function, I can prove that the ostream test fails: qdebug.h:219:5: error: static assertion failed due to requirement 'QTypeTraits::has_ostream_operator_v' But that test is: std::void_t() << detail::const_reference())> and if I copy that expression to the function, it does compile. Moreover, the changes to qdebug.h and qtypeinfo.h don't seem related. So I have no clue *why* the check fails and *how* it was fixed. This is template black magic. It works right now and I've spent enough time investigating. -- Thiago Macieira - thiago.macieira (AT) intel.com Cloud Software Architect - Intel DCAI Cloud Engineering smime.p7s Description: S/MIME cryptographic signature ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] can't dump QStringList with qDebug()
On 8/3/23 14:45, Thiago Macieira wrote: On Tuesday, 7 March 2023 17:21:11 PST Hamish Moffatt via Interest wrote: I said gcc 10 earlier, but I meant to say clang 11. But I also see it in clang 14, and in VS 2019 (17.5.1 - latest). Cannot reproduce with those files with GCC 11, 12, 13 or Clang 15, all with Qt 6.6. Looking at the generated assembly, I can also see the compiler realised the list is always empty, so the loop from printSequentialContainer() disappears.f I confirm that my test code compiles in 6.5.0-beta3. thanks Hamish ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] can't dump QStringList with qDebug()
On Tuesday, 7 March 2023 17:21:11 PST Hamish Moffatt via Interest wrote: > I said gcc 10 earlier, but I meant to say clang 11. But I also see it in > clang 14, and in VS 2019 (17.5.1 - latest). Cannot reproduce with those files with GCC 11, 12, 13 or Clang 15, all with Qt 6.6. Looking at the generated assembly, I can also see the compiler realised the list is always empty, so the loop from printSequentialContainer() disappears.f -- Thiago Macieira - thiago.macieira (AT) intel.com Cloud Software Architect - Intel DCAI Cloud Engineering smime.p7s Description: S/MIME cryptographic signature ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] can't dump QStringList with qDebug()
On 8/3/23 04:15, Thiago Macieira wrote:
On Monday, 6 March 2023 22:15:01 PST Hamish Moffatt via Interest wrote:
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdebug.h:217:53: note:
candidate template ignored: requirement
'std::conjunction_v,
QString>, QTypeTraits::has_ostream_operator>>' was
not satisfied [with T = QString]
This is the expected template and the compiler told us why it couldn't expand:
it thinks that the QDebugIfHasDebugStreamContainer condition wasn't satisfied.
That condition is
std::is_base_of OR QTypeTraits::has_ostream_operator
Obviously, QStringList is not a base class of QString; we're expecting the
second check to be true, that there's an output streaming operator for QDebug-
QString
That of course is there; it's in QDebug itself.
So my conclusion is that your compiler has a bug and improperly parsed the C++
code. Does this problem happen with GCC 11 or 12?
I said gcc 10 earlier, but I meant to say clang 11. But I also see it in
clang 14, and in VS 2019 (17.5.1 - latest).
It seems to be related to #including the moc output in the cpp file.
Here's a minimal example:
Header file:
#pragma once
#include
#include
namespace TServer
{
class Test : public QObject
{
Q_OBJECT
private:
void test();
signals:
void databaseOpened(QString schoolCode);
void databaseEvent(QString schoolCode, QString notification);
void databaseRemoved(QString schoolCode, QString dbFilename);
};
}
Source file:
#include "server_database2.h"
#include
#include
void TServer::Test::test()
{
qDebug() << QStringList{};
}
Hamish
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Re: [Interest] can't dump QStringList with qDebug()
On Monday, 6 March 2023 22:15:01 PST Hamish Moffatt via Interest wrote: > ../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdebug.h:217:53: note: > candidate template ignored: requirement > 'std::conjunction_v, > QString>, QTypeTraits::has_ostream_operator>>' was > not satisfied [with T = QString] This is the expected template and the compiler told us why it couldn't expand: it thinks that the QDebugIfHasDebugStreamContainer condition wasn't satisfied. That condition is std::is_base_of OR QTypeTraits::has_ostream_operator Obviously, QStringList is not a base class of QString; we're expecting the second check to be true, that there's an output streaming operator for QDebug- QString That of course is there; it's in QDebug itself. So my conclusion is that your compiler has a bug and improperly parsed the C++ code. Does this problem happen with GCC 11 or 12? -- Thiago Macieira - thiago.macieira (AT) intel.com Cloud Software Architect - Intel DCAI Cloud Engineering smime.p7s Description: S/MIME cryptographic signature ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] can't dump QStringList with qDebug()
Hi,
I'm sure you have already tried it, but just a wild guess: do you have
#include in this .cpp file?
Cheers
Dmitriy
On Tue, Mar 7, 2023 at 11:04 AM Hamish Moffatt via Interest <
interest@qt-project.org> wrote:
> On 7/3/23 20:11, Kai Köhne wrote:
> > Hi,
> >
> > This looks like a compiler issue to me.
> >> const auto connections = QSqlDatabase::connectionNames();
> >> qDebug() << "Closing open connections:" << connections;
> >>
> >> claiming that
> >> ../../../src/server/server_database.cpp:691:45: error: invalid operands
> to binary expression ('QDebug' and>
> >> 'const QList')
> > I think this is the place where it goes wrong:
> >
> >> ../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdebug.h:217:53: note:
> candidate template ignored: requirement
> 'std::conjunction_v,
> QString>, QTypeTraits::has_ostream_operator>>' was
> not satisfied [with T = QString]
> >> inline QDebugIfHasDebugStreamContainer, T> operator<<(QDebug
> debug, const QList )
> >> ^
> > Anyhow, I couldn't reproduce this in a minimal example (and apparently
> you didn't manage either?). At minimum we need the exact compiler +
> compiler options passed on command line.
>
>
> It's happening in both Visual C++ and gcc 10, but on further
> investigation, only in one .cpp file; the same code in other files works
> fine. I'll keep investigating.
>
>
> thanks
>
> Hamish
>
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Re: [Interest] can't dump QStringList with qDebug()
On 7/3/23 20:11, Kai Köhne wrote:
Hi,
This looks like a compiler issue to me.
const auto connections = QSqlDatabase::connectionNames();
qDebug() << "Closing open connections:" << connections;
claiming that
../../../src/server/server_database.cpp:691:45: error: invalid operands to binary
expression ('QDebug' and>
'const QList')
I think this is the place where it goes wrong:
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdebug.h:217:53: note: candidate template ignored:
requirement 'std::conjunction_v, QString>,
QTypeTraits::has_ostream_operator>>' was not satisfied [with T = QString]
inline QDebugIfHasDebugStreamContainer, T> operator<<(QDebug debug, const
QList )
^
Anyhow, I couldn't reproduce this in a minimal example (and apparently you
didn't manage either?). At minimum we need the exact compiler + compiler
options passed on command line.
It's happening in both Visual C++ and gcc 10, but on further
investigation, only in one .cpp file; the same code in other files works
fine. I'll keep investigating.
thanks
Hamish
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Re: [Interest] can't dump QStringList with qDebug()
Hi,
This looks like a compiler issue to me.
> const auto connections = QSqlDatabase::connectionNames();
> qDebug() << "Closing open connections:" << connections;
>
> claiming that
> ../../../src/server/server_database.cpp:691:45: error: invalid operands to
> binary expression ('QDebug' and>
> 'const QList')
I think this is the place where it goes wrong:
> ../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdebug.h:217:53: note:
> candidate template ignored: requirement
> 'std::conjunction_v,
> QString>, QTypeTraits::has_ostream_operator>>' was not
> satisfied [with T = QString]
> inline QDebugIfHasDebugStreamContainer, T> operator<<(QDebug debug,
> const QList )
> ^
Anyhow, I couldn't reproduce this in a minimal example (and apparently you
didn't manage either?). At minimum we need the exact compiler + compiler
options passed on command line.
I also suggest to move this to bugreports.qt.io.
Regards
Kai
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[Interest] can't dump QStringList with qDebug()
I'm porting my code to Qt6 (6.4.2) (from 5.15) and ran into this
mysterious problem; this code doesn't compile:
const auto connections = QSqlDatabase::connectionNames();
qDebug() << "Closing open connections:" << connections;
claiming that
../../../src/server/server_database.cpp:691:45: error: invalid operands
to binary expression ('QDebug' and 'const QList')
It then lists all the candidates, of which there are many. I have a
simple test program that compiles OK though.
The same occurs on both Visual Studio/Windows and gcc 10/Linux.
Am I missing an include or something?
Hamish
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdatastream.h:398:1: note:
candidate function template not viable: no known conversion from 'QDebug' to
'QDataStream &' for 1st argument
operator<<(QDataStream , const T )
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdatastream.h:415:63: note:
candidate function template not viable: no known conversion from 'QDebug' to
'QDataStream &' for 1st argument
inline QDataStreamIfHasOStreamOperatorsContainer, T> operator<<(QDataStream ,
const QList )
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qobject.h:491:22: note: candidate
function not viable: no known conversion from 'const QList' to 'const
QObject *' for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug, const QObject *);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtSql/qsqldatabase.h:105:21: note: candidate
function not viable: no known conversion from 'const QList' to 'const
QSqlDatabase' for 2nd argument
Q_SQL_EXPORT QDebug operator<<(QDebug, const QSqlDatabase &);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdebug.h:447:15: note: candidate
function not viable: no known conversion from 'const QList' to
'QKeyCombination' for 2nd argument
inline QDebug operator<<(QDebug debug, QKeyCombination combination)
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qiodevice.h:143:22: note: candidate
function not viable: no known conversion from 'const QList' to
'QIODevice::OpenMode' (aka 'QFlags') for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug debug, QIODevice::OpenMode modes);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qvariant.h:560:28: note: candidate
function not viable: no known conversion from 'QDebug' to 'QDataStream &' for
1st argument
Q_CORE_EXPORT QDataStream <<(QDataStream , const QVariant );
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qvariant.h:622:22: note: candidate
function not viable: no known conversion from 'const QList' to 'const
QVariant::Type' for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug, const QVariant::Type);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qlocale.h:1142:22: note: candidate
function not viable: no known conversion from 'const QList' to 'const
QLocale' for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug, const QLocale &);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdatetime.h:540:22: note: candidate
function not viable: no known conversion from 'const QList' to 'QDate'
for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug, QDate);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdatetime.h:541:22: note: candidate
function not viable: no known conversion from 'const QList' to 'QTime'
for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug, QTime);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdatetime.h:542:22: note: candidate
function not viable: no known conversion from 'const QList' to 'const
QDateTime' for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug, const QDateTime &);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qfileinfo.h:175:22: note: candidate
function not viable: no known conversion from 'const QList' to 'const
QFileInfo' for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug, const QFileInfo &);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdir.h:244:22: note: candidate function not
viable: no known conversion from 'const QList' to 'QDir::Filters' (aka
'QFlags') for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug debug, QDir::Filters filters);
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qdir.h:245:22: note: candidate
function not viable: no known conversion from 'const QList' to 'const
QDir' for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug debug, const QDir );
^
../../../../Qt6.4.2/6.4.2/gcc_64/include/QtCore/qregularexpression.h:166:22: note:
candidate function not viable: no known conversion from 'const QList'
to 'const QRegularExpression' for 2nd argument
Q_CORE_EXPORT QDebug operator<<(QDebug debug, const QRegularExpression );
^
