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Details

Type: Task
Resolution: Done
Priority: P0: Blocker
Fix Version/s: None
Affects Version/s: 6.0.0 Alpha
Component/s: Core: Containers and Algorithms, Core: I/O
Labels:
None

Commits:
b83225fcc3c6aa5655884cbf9e7391afe38b4392 (qt/qtbase/dev)

Description

This snippet

#include <QtCore>

class S {
public:
    operator QVariant() const {
        return QVariant::fromValue(*this);
    }
};

Q_DECLARE_METATYPE(S)

int main() {
    S s;
    qDebug() << s;
}

Has two major problems:

it compiles even without a QDebug operator for S
it causes a stack overflow at runtime due to an endless recursion

#0  0x00007ffff74a925e in TestNamespace::QArrayDataPointer<char16_t>::begin (this=<error reading variable: Cannot access memory at address 0x7fffff7feff8>) at ../../include/QtCore/../../src/corelib/tools/qarraydatapointer.h:142
#1  0x00007ffff74afb78 in void TestNamespace::QtPrivate::QCommonArrayOps<char16_t>::prepareFreeSpace<TestNamespace::QtPrivate::GrowsForwardTag, char16_t const*>(TestNamespace::QtPrivate::GrowsForwardTag, unsigned long, unsigned long, char16_t const*&, char16_t const*&)::{lambda(char16_t const* const&, char16_t const* const&)#1}::operator()(char16_t const* const&, char16_t const* const&) const (this=0x55555577aca0, first=@0x7fffff7ff130: 0x55555577b3d0 u"QVariant(", 
    last=@0x7fffff7ff128: 0x55555577b3e2 u"") at ../../include/QtCore/../../src/corelib/tools/qarraydataops.h:1228
#2  0x00007ffff74afc4a in TestNamespace::QtPrivate::QCommonArrayOps<char16_t>::prepareFreeSpace<TestNamespace::QtPrivate::GrowsForwardTag, char16_t const*> (this=0x55555577aca0, tag=..., required=9, moveSize=0, 
    b=@0x7fffff7ff130: 0x55555577b3d0 u"QVariant(", e=@0x7fffff7ff128: 0x55555577b3e2 u"") at ../../include/QtCore/../../src/corelib/tools/qarraydataops.h:1234
#3  0x00007ffff74ad5d7 in TestNamespace::QtPrivate::QCommonArrayOps<char16_t>::prepareSpaceForAppend<char16_t const*> (this=0x55555577aca0, b=@0x7fffff7ff130: 0x55555577b3d0 u"QVariant(", e=@0x7fffff7ff128: 0x55555577b3e2 u"", required=9)
    at ../../include/QtCore/../../src/corelib/tools/qarraydataops.h:1270
#4  0x00007ffff74aa088 in TestNamespace::QtPrivate::QCommonArrayOps<char16_t>::copyAppend (this=0x55555577aca0, b=0x55555577b3d0 u"QVariant(", e=0x55555577b3e2 u"") at ../../include/QtCore/../../src/corelib/tools/qarraydataops.h:1371
#5  0x00007ffff74927d1 in TestNamespace::QString::append (this=0x55555577aca0, str=0x55555577b3d0, len=9) at text/qstring.cpp:2831
#6  0x00007ffff77cd021 in TestNamespace::QTextStreamPrivate::write (this=0x55555577acf0, data=0x55555577b3d0, len=9) at serialization/qtextstream.cpp:761
#7  0x00007ffff77cd483 in TestNamespace::QTextStreamPrivate::putString (this=0x55555577acf0, data=0x55555577b3d0, len=9, number=false) at serialization/qtextstream.cpp:916
#8  0x00007ffff7528aad in TestNamespace::QTextStreamPrivate::putString (this=0x55555577acf0, ch=..., number=false) at ../../include/QtCore/6.0.0/QtCore/private/../../../../../src/corelib/serialization/qtextstream_p.h:177
#9  0x00007ffff77d249d in TestNamespace::QTextStream::operator<< (this=0x55555577ac90, string=...) at serialization/qtextstream.cpp:2516
#10 0x00007ffff7365a9b in TestNamespace::QDebug::operator<< (this=0x7fffff7ff450, t=0x7ffff79b22e8 "QVariant(") at ../../include/QtCore/../../src/corelib/io/qdebug.h:141
#11 0x00007ffff77766c5 in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2376
#12 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ff580) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#13 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ff510, dbg=..., rhs=0x7fffff7ff580) at kernel/qmetatype.cpp:1709
#14 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#15 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ff6a0) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#16 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ff630, dbg=..., rhs=0x7fffff7ff6a0) at kernel/qmetatype.cpp:1709
#17 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#18 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ff7c0) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#19 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ff750, dbg=..., rhs=0x7fffff7ff7c0) at kernel/qmetatype.cpp:1709
#20 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#21 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ff8e0) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#22 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ff870, dbg=..., rhs=0x7fffff7ff8e0) at kernel/qmetatype.cpp:1709
#23 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#24 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ffa00) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#25 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ff990, dbg=..., rhs=0x7fffff7ffa00) at kernel/qmetatype.cpp:1709
#26 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#27 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ffb20) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#28 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ffab0, dbg=..., rhs=0x7fffff7ffb20) at kernel/qmetatype.cpp:1709
#29 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#30 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ffc40) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#31 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ffbd0, dbg=..., rhs=0x7fffff7ffc40) at kernel/qmetatype.cpp:1709
#32 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#33 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ffd60) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#34 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ffcf0, dbg=..., rhs=0x7fffff7ffd60) at kernel/qmetatype.cpp:1709
#35 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#36 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7ffe80) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#37 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7ffe10, dbg=..., rhs=0x7fffff7ffe80) at kernel/qmetatype.cpp:1709
#38 0x00007ffff777673e in TestNamespace::operator<< (dbg=..., v=...) at kernel/qvariant.cpp:2379
#39 0x00005555555564f8 in TestNamespace::QtPrivate::QDebugStreamOperatorForType<S, true>::debugStream (dbg=..., a=0x7fffff7fffa0) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:2086
#40 0x00007ffff7703b51 in TestNamespace::QMetaType::debugStream (this=0x7fffff7fff30, dbg=..., rhs=0x7fffff7fffa0) at kernel/qmetatype.cpp:1709

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Assignee:: Fabian Kosmale

Reporter:: Giuseppe D'Angelo

Votes:: 0 Vote for this issue

Watchers:: 6 Start watching this issue

Dates

Created:: 02 Oct '20 09:27

Updated:: 13 Oct '20 08:13

Resolved:: 13 Oct '20 08:13

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qDebug: Avoid implicit QVariant conversion: Gerrit Review: