[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547 Mladen Milinkovic, Max changed: What|Removed |Added Status|CONFIRMED |RESOLVED Resolution|--- |FIXED --- Comment #13 from Mladen Milinkovic, Max --- Have merged the fix to the master branch. Feel free to re-open this issue if you still have problems. Also you can open MR on https://invent.kde.org/multimedia/subtitlecomposer if you'd like to provide better solution. Thanks for the report and your time. -- You are receiving this mail because: You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547
--- Comment #12 from Mladen Milinkovic, Max ---
(In reply to Matthias Grimrath from comment #11)
> You dare to go, were I wouldn't, by using allocators :D
>
> This, however, looks suspicious to me
>
> inline bool inContainer() {
> const auto &a = container()->get_allocator();
> return this >= a.lastData && this < a.lastData + a.lastSize;
>
> so the pointer is compared against the allocated memory. However, a pointer
> somewhere into that allocated memory may not point to an actually used
> element. We saw QVector<> reserving some space at the beginning to be able
> to quickly insert elements at the top. And a STL implementation of
> std::vector<> is probably allowed to do the same.
As long as memory is allocated to that container it's fine IMHO, regardless if
it's reserved or used.
If something is moving object into memory allocated by m_lines it's about to
become or already is member of m_lines.
> I don't know weather that leads to real-world problems. But I feel uneasy
> about it.
>
> I think a better approach would be to control insertion of new elements into
> 'm_lines' and update indices there, instead of hooking into QVector<> or
> std::vector<> by template magic. Should be the same performance wise.
It's not magic - just code :D - and this one doesn't rely on unspecified
internal implementation of std::vector. Previous version relied on QVector
constructing elements in memory between begin() and end() (it had to update
begin/end() *before* move/copy/constructing element object).
If you want to do PR it's fine by me - although keep in mind that similar
approach was used before and it wasn't working well. At times when subtitle or
undo stack handling code was touched it often caused subtle bugs and it was
maintenance nightmare. Sorting performance was awful due to index recalculation
every time lines would get swapped and so on. :)
> I'll work on a patch, having real code to show is probably better than
> sophisticated arguments :D
The safest (code wise) and best (performance wise) would be to use custom array
class and handle memory allocation directly, but I'm quite happy with custom
allocator like it is now.
--
You are receiving this mail because:
You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547
--- Comment #11 from Matthias Grimrath ---
You dare to go, were I wouldn't, by using allocators :D
This, however, looks suspicious to me
inline bool inContainer() {
const auto &a = container()->get_allocator();
return this >= a.lastData && this < a.lastData + a.lastSize;
so the pointer is compared against the allocated memory. However, a pointer
somewhere into that allocated memory may not point to an actually used element.
We saw QVector<> reserving some space at the beginning to be able to quickly
insert elements at the top. And a STL implementation of std::vector<> is
probably allowed to do the same.
I don't know weather that leads to real-world problems. But I feel uneasy about
it.
I think a better approach would be to control insertion of new elements into
'm_lines' and update indices there, instead of hooking into QVector<> or
std::vector<> by template magic. Should be the same performance wise.
I'll work on a patch, having real code to show is probably better than
sophisticated arguments :D
--
You are receiving this mail because:
You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547 Mladen Milinkovic, Max changed: What|Removed |Added Ever confirmed|0 |1 Status|REPORTED|CONFIRMED --- Comment #10 from Mladen Milinkovic, Max --- Have changed ObjectRef and m_lines to use std::vector with custom allocator, so that the code doesn't rely anymore on QVector's internal implementation. Still haven't pushed it to master as I want to test and clean it up some more. You can checkout work/maxrd2/vector branch if you'd like to try it out. https://invent.kde.org/multimedia/subtitlecomposer/-/commits/work/maxrd2/vector?ref_type=heads -- You are receiving this mail because: You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547 --- Comment #9 from Mladen Milinkovic, Max --- Apologies I was building with wrong Qt version instead of system's 6.9.1. I have managed to reproduce it here. -- You are receiving this mail because: You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547
--- Comment #8 from Matthias Grimrath ---
I added some additional debug output (see attached patch) which reveals what
triggers the assertion on my computer.
The 'ObjectRef<>' class checks wether the pointer points inside the QVector<>
array, and if not, leaves 'm_ref' at its NULL value. So added I some code to
print the pointer values if a call to 'ref()' or 'movref()' skips assigning to
'm_ref' because of that.
this=0x55f500b0 beg=0x55f500c0 end=0x55f502b0 cap=31 len=9
this=0x55f500b0 m_obj=0x59314e80 ignoring
ASSERT: "m_ref != nullptr" in file
/home/matthias/build/subtitlecomposer-upstream/src/core/subtitleline.cpp, line
230
What is odd is that the 'this' value (0x55f500b0) is exactly one element
before the beginning of the QVector<> array (0x55f500c0). So 'm_ref' is
left at its NULL value, although it suspiciously looks like it should be a
member of the 'QVector<>' object.
If a set a breakpoint at the code where it decides not to set 'm_ref'
(gdb) b ObjectRef::inContainerXXX()
I get this backtrace:
(gdb) bt
#0 SubtitleComposer::ObjectRef::inContainerXXX
(this=this@entry=0x7fffb4c0)
at
/home/matthias/build/subtitlecomposer-upstream/src/helpers/objectref.h:82
#1 0x555c5e0a in
SubtitleComposer::ObjectRef::moveref
(this=this@entry=0x7fffb4c0, other=other@entry=0x7fffb580)
at
/home/matthias/build/subtitlecomposer-upstream/src/helpers/objectref.h:62
#2 0x55615df8 in
SubtitleComposer::ObjectRef::ObjectRef
(this=0x7fffb4c0, other=...)
at
/home/matthias/build/subtitlecomposer-upstream/src/helpers/objectref.h:35
#3
QtPrivate::QGenericArrayOps
>::emplace >
(this=this@entry=0x561fc090, i=i@entry=0) at
/usr/include/qt6/QtCore/qarraydataops.h:545
The code at qarraydataops.h:545 reveals what happens here:
if (growsAtBegin) {
Q_ASSERT(this->freeSpaceAtBegin());
new (this->begin() - 1) T(std::move(tmp));
--this->ptr;
++this->size;
} else {
So QVector<> *does* call the constructor of ObjectRef<>, but it hasn't updated
its internal pointers yet. So when 'inContainer()' checks the pointer, it gets
outdated values from the QVector<> object and thus wrongly assumes the
'SubtitleLine' pointer is outside the array.
--
You are receiving this mail because:
You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547 --- Comment #7 from Matthias Grimrath --- Created attachment 183632 --> https://bugs.kde.org/attachment.cgi?id=183632&action=edit debug output in ObjectRef<> class -- You are receiving this mail because: You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547 --- Comment #6 from Matthias Grimrath --- I think I found the found problem, but I still need to work out the details and write it up. I don't like to say it, but it looks like there is indeed a deep flaw (as far as C++ semantics are concerned) in the 'ObjectRef' template class used inside a 'QVector<>'. (In reply to Mladen Milinkovic, Max from comment #5) > As I said before I think your compiler is optimizing too much code. > I have done exact same test on current arch linux and cannot reproduce the > problem. I think what triggers the assertion on my computer is not too much optimization, but the lack thereof. Did you configure and build subtitle-composer in a debug build as I did? As I wrote above, I invoked 'cmake' with build type set to 'Debug' and recompiled from scratch without optimizations. $ cmake -DQT_MAJOR_VERSION=6 -DCMAKE_BUILD_TYPE=Debug -- You are receiving this mail because: You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547 --- Comment #5 from Mladen Milinkovic, Max --- (In reply to Matthias Grimrath from comment #2) > (In reply to Mladen Milinkovic, Max from comment #1) > > I would appreciate exact message that is written - it should says something > > like: > ASSERT: "m_ref != nullptr" in file > /home/matthias/build/subtitlecomposer-upstream/src/core/subtitleline.cpp, > line 230 As I said before I think your compiler is optimizing too much code. I have done exact same test on current arch linux and cannot reproduce the problem. QVector when growing copies the existing values into newly allocated bigger buffer. When vector contains C++ objects it's supposed to copy/move construct them depending if they are *NOT* Q_MOVABLE_TYPE. If they are Q_MOVABLE_TYPE QVector can just memcpy old data to new buffer without calling any constructors. Since ObjectRef is not Q_MOVABLE_TYPE, QVector is supposed to call C++ constructor when growing - which in turns assign m_ref to something non-null on newly created ObjectRef instances. Your build triggering Q_ASSERT(m_ref != nullptr) means that for whatever reason QVector when growing is not constructing C++ objects, but just memcpy-ing their memory. I'm not sure why is that happening, if you feel like investigating you could try building Qt yourself and checking what's going on in qvector.cpp (you will see Q_MOVABLE_TYPE if conditions for optimizations). In any case if you just disable asserts (or remove those two asserts) the code will continue working as it was and it will log that qWarning whenever it it's uynable to correctly calculate index of the element. In that case it will fallback to original for loop that was used to figure out the subtitle line index. -- You are receiving this mail because: You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547 --- Comment #4 from Matthias Grimrath --- How I build subtitle-composer $ cat build.sh # my script to configure and compile cmake -B /tmp/build-subtitle -G Ninja -DQT_MAJOR_VERSION=6 -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=/tmp/inst-subtitle ninja -C /tmp/build-subtitle -j 12 ninja -C /tmp/build-subtitle install # excerpts from build log $ touch src/core/subtitleline.cpp $ ninja -v -C /tmp/build-subtitle/ [4/14] /usr/bin/c++ -DKCOREADDONS_LIB -DKGUIADDONS_LIB -DQT_CORE5COMPAT_LIB -DQT_CORE_LIB -DQT_DBUS_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_OPENGLWIDGETS_LIB -DQT_OPENGL_LIB -DQT_QMLINTEGRATION_LIB -DQT_QML_LIB -DQT_WIDGETS_LIB -DQT_XML_LIB -D_DEFAULT_SOURCE -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -I/tmp/build-subtitle/src -I/home/matthias/build/subtitlecomposer-upstream/src -I/tmp/build-subtitle/src/subtitlecomposer-lib_autogen/include -I/home/matthias/build/subtitlecomposer-upstream/src/widgets -I/usr/include/qt6/QtDBus/6.9.0 -I/usr/include/qt6/QtDBus/6.9.0/QtDBus -I/usr/include/AL -isystem /usr/include/qt6/QtCore -isystem /usr/include/qt6 -isystem /usr/include/qt6/QtWidgets -isystem /usr/include/qt6/QtGui -isystem /usr/include/qt6/QtDBus -isystem /usr/include/qt6/QtWidgets/6.9.0 -isystem /usr/include/qt6/QtWidgets/6.9.0/QtWidgets -isystem /usr/include/qt6/QtCore/6.9.0 -isystem /usr/include/qt6/QtCore/6.9.0/QtCore -isystem /usr/include/qt6/QtGui/6.9.0 -isystem /usr/include/qt6/QtGui/6.9.0/QtGui -isystem /usr/lib/qt6/mkspecs/linux-g++ -isystem /usr/include/qt6/QtQml -isystem /usr/include/qt6/QtQmlIntegration -isystem /usr/include/qt6/QtNetwork -isystem /usr/include/KF6/KCoreAddons -isystem /usr/include/KF6/KWidgetsAddons -isystem /usr/include/KF6/KTextWidgets -isystem /usr/include/KF6/SonnetUi -isystem /usr/include/KF6/Sonnet -isystem /usr/include/KF6/KI18n -isystem /usr/include/KF6/KCodecs -isystem /usr/include/KF6/SonnetCore -isystem /usr/include/KF6/KIOCore -isystem /usr/include/KF6/KIO -isystem /usr/include/KF6/KIOFileWidgets -isystem /usr/include/KF6/KIOWidgets -isystem /usr/include/KF6/KIOGui -isystem /usr/include/KF6/KConfig -isystem /usr/include/KF6/KConfigCore -isystem /usr/include/KF6/KService -isystem /usr/include/KF6/KJobWidgets -isystem /usr/include/KF6/Solid -isystem /usr/include/KF6/KCompletion -isystem /usr/include/KF6/KBookmarks -isystem /usr/include/qt6/QtXml -isystem /usr/include/KF6/KItemViews -isystem /usr/include/KF6/KXmlGui -isystem /usr/include/KF6/KConfigWidgets -isystem /usr/include/KF6/KConfigGui -isystem /usr/include/KF6/KColorScheme -isystem /usr/include/KF6/KGuiAddons -isystem /usr/include/qt6/QtOpenGLWidgets -isystem /usr/include/qt6/QtOpenGL -isystem /usr/include/qt6/QtCore5Compat -fno-operator-names -fno-exceptions -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wnon-virtual-dtor -Woverloaded-virtual -Werror=return-type -Werror=init-self -Wvla -Wdate-time -Wsuggest-override -Wlogical-op -fdiagnostics-color=always -g -Wall -Og -g -std=gnu++17 -fvisibility=hidden -fvisibility-inlines-hidden -mno-direct-extern-access -MD -MT src/CMakeFiles/subtitlecomposer-lib.dir/core/subtitleline.cpp.o -MF src/CMakeFiles/subtitlecomposer-lib.dir/core/subtitleline.cpp.o.d -o src/CMakeFiles/subtitlecomposer-lib.dir/core/subtitleline.cpp.o -c /home/matthias/build/subtitlecomposer-upstream/src/core/subtitleline.cpp -- You are receiving this mail because: You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547
--- Comment #3 from Matthias Grimrath ---
# backtrace of failed assertion
(gdb) bt
#0 0x70ea5ddc in ?? () from /usr/lib/libc.so.6
#1 0x70e4f4d8 in raise () from /usr/lib/libc.so.6
#2 0x70e37669 in abort () from /usr/lib/libc.so.6
#3 0x714911dc in ?? () from /usr/lib/libQt6Core.so.6
#4 0x714920ee in QMessageLogger::fatal(char const*, ...) const () from
/usr/lib/libQt6Core.so.6
#5 0x7148f7d6 in qt_assert(char const*, char const*, int) () from
/usr/lib/libQt6Core.so.6
#6 0x555f941f in SubtitleComposer::SubtitleLine::index
(this=0x592b3320) at
/home/matthias/build/subtitlecomposer-upstream/src/core/subtitleline.cpp:230
#7 0x5565fd32 in SubtitleComposer::LinesModel::onModelReset
(this=this@entry=0x55fa7b60)
at
/home/matthias/build/subtitlecomposer-upstream/src/gui/treeview/linesmodel.cpp:339
#8 0x55617430 in SubtitleComposer::LinesModel::processSelectionUpdate
(this=0x55fa7b60)
at
/home/matthias/build/subtitlecomposer-upstream/src/gui/treeview/linesmodel.h:51
#9 0x55616d7d in saveSelection (current=0x55bd7e0c,
selection=0x55bd7e28) at
/home/matthias/build/subtitlecomposer-upstream/src/core/undo/undostack.cpp:81
#10 0x55616e41 in SubtitleComposer::UndoStack::levelDecrease
(this=this@entry=0x56102790, idx=idx@entry=1)
at
/home/matthias/build/subtitlecomposer-upstream/src/core/undo/undostack.cpp:109
#11 0x556173ae in SubtitleComposer::UndoStack::push
(this=0x56102790, cmd=0x594117d0)
at
/home/matthias/build/subtitlecomposer-upstream/src/core/undo/undostack.cpp:121
#12 0x555eb0b8 in SubtitleComposer::Subtitle::processAction
(this=this@entry=0x59232ca0, action=action@entry=0x594117d0)
at
/home/matthias/build/subtitlecomposer-upstream/src/core/subtitle.cpp:1390
#13 0x555ebd07 in SubtitleComposer::Subtitle::insertLine
(this=this@entry=0x59232ca0, line=line@entry=0x592b3320,
index=index@entry=0)
at /home/matthias/build/subtitlecomposer-upstream/src/core/subtitle.cpp:361
#14 0x555ecb8e in SubtitleComposer::Subtitle::insertNewLine
(this=this@entry=0x59232ca0, index=0, insertAfter=insertAfter@entry=false,
target=target@entry=SubtitleComposer::Both) at
/home/matthias/build/subtitlecomposer-upstream/src/core/subtitle.cpp:400
#15 0x555bbc37 in
SubtitleComposer::Application::insertBeforeCurrentLine (this=0x7fffdd30) at
/home/matthias/build/subtitlecomposer-upstream/src/application.cpp:420
#16 0x555c60ee in QtPrivate::FunctorCall, QtPrivate::List<>, void, void
(SubtitleComposer::Application::*)()>::call(void
(SubtitleComposer::Application::*)(), SubtitleComposer::Application*,
void**)::{lambda()#1}::operator()() const
(__closure=__closure@entry=0x7fffb8c0)
at /usr/include/qt6/QtCore/qobjectdefs_impl.h:127
#17 0x555c709c in QtPrivate::FunctorCallBase::call_internal, QtPrivate::List<>,
void, void (SubtitleComposer::Application::*)()>::call(void
(SubtitleComposer::Application::*)(), SubtitleComposer::Application*,
void**)::{lambda()#1}>(void**,
QtPrivate::FunctorCall, QtPrivate::List<>,
void, void (SubtitleComposer::Application::*)()>::call(void
(SubtitleComposer::Application::*)(), SubtitleComposer::Application*,
void**)::{lambda()#1}&&) (args=, fn=...) at
/usr/include/qt6/QtCore/qobjectdefs_impl.h:65
#18 QtPrivate::FunctorCall,
QtPrivate::List<>, void, void (SubtitleComposer::Application::*)()>::call(void
(SubtitleComposer::Application::*)(), SubtitleComposer::Application*, void**) (
f=(void (SubtitleComposer::Application::*)(SubtitleComposer::Application *
const)) 0x555bbb52
,
o=, arg=) at
/usr/include/qt6/QtCore/qobjectdefs_impl.h:126
#19 0x555c70ee in QtPrivate::FunctionPointer::call, void>(void
(SubtitleComposer::Application::*)(), SubtitleComposer::Application*, void**)
(f=, o=, arg=) at
/usr/include/qt6/QtCore/qobjectdefs_impl.h:174
#20 QtPrivate::QCallableObject, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*,
void**, bool*) (
which=, this_=, r=,
a=, ret=) at
/usr/include/qt6/QtCore/qobjectdefs_impl.h:545
#21 0x715b2dba in ?? () from /usr/lib/libQt6Core.so.6
#22 0x72164f99 in QAction::activate(QAction::ActionEvent) () from
/usr/lib/libQt6Gui.so.6
#23 0x728d809a in ?? () from /usr/lib/libQt6Widgets.so.6
#24 0x728dce99 in ?? () from /usr/lib/libQt6Widgets.so.6
#25 0x7274eecf in QWidget::event(QEvent*) () from
/usr/lib/libQt6Widgets.so.6
#26 0x726fea7b in QApplicationPrivate::notify_helper(QObject*, QEvent*)
() from /usr/lib/libQt6Widgets.so.6
#27 0x72702803 in QApplication::notify(QObject*, QEvent*) () from
/usr/lib/libQt6Widgets.so.6
#28 0x71557f48 in QCoreApplication::notifyInternal2(QObject*, QEvent*)
() from /usr/lib/libQt6Core.so.6
#29 0x726f6833 in QApplicationPrivate::sendMouseEvent(QWidget*,
QMouseEvent*, QWidget*, QWidget*, Q
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547
--- Comment #2 from Matthias Grimrath ---
(In reply to Mladen Milinkovic, Max from comment #1)
> I would appreciate exact message that is written - it should says something
> like:
ASSERT: "m_ref != nullptr" in file
/home/matthias/build/subtitlecomposer-upstream/src/core/subtitleline.cpp, line
230
Build from this source:
branch 'master' of https://invent.kde.org/multimedia/subtitlecomposer
commit a5a9b4916787f3b5263945cd63840fcb8e5a43cf (HEAD -> master, origin/master,
origin/HEAD)
Author: l10n daemon script
Date: Wed Jul 16 03:01:03 2025 +
GIT_SILENT Sync po/docbooks with svn
> According to C++ specs?
This is the code in question:
Q_ASSERT(m_ref != nullptr);
Q_ASSERT(m_ref->m_obj == this);
const int index = m_ref - m_subtitle->m_lines.constData();
if(index < 0 || index >= m_subtitle->count()) { ...
So if 'm_ref' is NULL, 'index' contains garbage. Maybe it's not undefined by
specification - I'm no language lawyer :) - but nevertheless I think it is not
desirable. In practice though the bogus value in 'index' probably triggers the
following 'if' clause, so the still-in-place work-around code amends the
situation.
> > SOFTWARE/OS VERSIONS
> It shouldn't, but please:
> - What OS and version are you using?
Artix Linux, Arch derivative, a rolling release distribution
> - What compiler and version are you using? Is it one shipped with that
> OS/distribution?
yes, from the distribution
$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/15.1.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure
--enable-languages=ada,c,c++,d,fortran,go,lto,m2,objc,obj-c++,rust,cobol
--enable-bootstrap --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib
--mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=https://gitea.artixlinux.org/packages/gcc/issues
--with-build-config=bootstrap-lto --with-linker-hash-style=gnu
--with-system-zlib --enable-__cxa_atexit --enable-cet=auto
--enable-checking=release --enable-clocale=gnu --enable-default-pie
--enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object
--enable-libstdcxx-backtrace --enable-link-serialization=1
--enable-linker-build-id --enable-lto --enable-multilib --enable-plugin
--enable-shared --enable-threads=posix --disable-libssp --disable-libstdcxx-pch
--disable-werror
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 15.1.1 20250425 (GCC)
> - What Qt version are you using? Is it one shipped with that OS/distribution?
Yes, pacman says 'local/qt6-base 6.9.0-1 (qt6)'
> If the assert says:
> ASSERT: "m_ref != nullptr" in file ./subtitleline.cpp, line 230
> your compiler is optimizing too much away and not calling object
> constructors when resizing vectors.
>
> I saw this happen in some old Linux Mint build worker, but was unable to
> reproduce it anywhere.
In my experience C++ (not only) template semantics are very tricky. So I
wouldn't be surprised if the language spec allows that constructors in this
case here (Qt Linesmodel) may not be called as one would expect.
For this same reason (tricky semantics) I try to avoid using own non-trivial
classes with STL containers.
--
You are receiving this mail because:
You are watching all bug changes.
[subtitlecomposer] [Bug 507547] Failed assertion when inserting a new subtitle line above the first.
https://bugs.kde.org/show_bug.cgi?id=507547 --- Comment #1 from Mladen Milinkovic, Max --- Thanks for the report. I cannot reproduce it here. > - failed assertion: 'm_ref' is null, but it shouldn't I would appreciate exact message that is written - it should says something like: ASSERT: "" in file xxx/x.cpp, line yyy > According to C++ specs, in release builds, program behaviour after the failed > assertion is undefined, though in practice it is not. According to C++ specs? > SOFTWARE/OS VERSIONS > - shouldn't matter It shouldn't, but please: - What OS and version are you using? - What compiler and version are you using? Is it one shipped with that OS/distribution? - What Qt version are you using? Is it one shipped with that OS/distribution? If the assert says: ASSERT: "m_ref != nullptr" in file ./subtitleline.cpp, line 230 your compiler is optimizing too much away and not calling object constructors when resizing vectors. I saw this happen in some old Linux Mint build worker, but was unable to reproduce it anywhere. -- You are receiving this mail because: You are watching all bug changes.
