cura 2.3.1-2 segfault on startup in libQt5Gui #1393
Comments
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See also my comment here: #1072 (comment) In short, this is due to a bug in PyQt which does not yet officially support Qt 5.8. There is currently no real known workaround. |
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This crash still happens with PyQt5.8 which is officially released since a few days: https://www.riverbankcomputing.com/software/pyqt/download5 |
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Yeah. It seems like pyqt5.8 didn't fix it. I've rebuilt everything and I'm still getting a segfault: |
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I have now reported the crash upstream, waiting to see what the reaction is. |
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@awhiemstra thanks. Can you give a link to your bug report? |
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There is no bugtracker for PyQt, everything goes through the mailing list. This is ML thread: https://www.riverbankcomputing.com/pipermail/pyqt/2017-February/038875.html |
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No wonder I couldn't find one! |
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Phil Thompson (PyQt5 dev) fixed the problem: https://www.riverbankcomputing.com/pipermail/pyqt/2017-February/038909.html So I identified, extracted and tested the patch from the snapshot: --- a/qpy/QtQml/qpyqml_register_type.cpp 2017-02-23 03:32:51.000000000 +0100
+++ b/qpy/QtQml/qpyqml_register_type.cpp 2017-02-25 03:32:58.000000000 +0100
@@ -124,13 +124,13 @@
#define QPYQML_TYPE_INIT(n) \
case n##U: \
- QPyQmlObject##n::staticMetaObject = *mo; \
+ QPyQmlObject##n::staticMetaObject = static_mo; \
QPyQmlObject##n::attachedPyType = attached; \
rt->typeId = qRegisterNormalizedMetaType<QPyQmlObject##n *>(ptr_name); \
rt->listId = qRegisterNormalizedMetaType<QQmlListProperty<QPyQmlObject##n> >(list_name); \
rt->objectSize = ctor ? sizeof(QPyQmlObject##n) : 0; \
if (ctor) rt->create = QQmlPrivate::createInto<QPyQmlObject##n>; else rt->create = 0; \
- rt->metaObject = mo; \
+ rt->metaObject = &QPyQmlObject##n::staticMetaObject; \
rt->attachedPropertiesFunction = attached_mo ? QPyQmlObject##n::attachedProperties : 0; \
rt->attachedPropertiesMetaObject = attached_mo; \
rt->parserStatusCast = is_parser_status ? QQmlPrivate::StaticCastSelector<QPyQmlObject##n,QQmlParserStatus>::cast() : -1; \
@@ -219,7 +219,33 @@
return 0;
}
- const QMetaObject *mo = pyqt5_qtqml_get_qmetaobject(py_type);
+ const QMetaObject *orig_mo = pyqt5_qtqml_get_qmetaobject(py_type);
+ QMetaObject static_mo = *orig_mo;
+
+#if QT_VERSION >= 0x050800
+ // Qt v5.8.0 changed the way properties are handled by directly calling a
+ // class's static meta-call (if there was one) directly. This bypasses the
+ // proxy and calls the static meta-call with a pointer to the proxy rather
+ // than a pointer to the real object. To work round this we clone the
+ // QMetaObject chain and remove the references to the static meta-call
+ // forcing the earlier behaviour. This approach may also work with earlier
+ // versions of Qt - but if it ain't broke...
+ static_mo.d.static_metacall = 0;
+
+ QMetaObject *sub_mo = &static_mo;
+
+ // By retaining the QObject static meta-object we don't appear to be a
+ // gadget.
+ for (const QMetaObject *mo = sub_mo->d.superdata; mo != &QObject::staticMetaObject; mo = mo->d.superdata)
+ {
+ QMetaObject *new_mo = new QMetaObject;
+ *new_mo = *mo;
+ new_mo->d.static_metacall = 0;
+
+ sub_mo->d.superdata = new_mo;
+ sub_mo = new_mo;
+ }
+#endif
// See if the type is a parser status.
bool is_parser_status = PyType_IsSubtype(py_type,
@@ -272,7 +298,7 @@
if (qquickitem_register)
{
- sipErrorState estate = qquickitem_register(py_type, mo, ptr_name,
+ sipErrorState estate = qquickitem_register(py_type, orig_mo, ptr_name,
list_name, &rt);
if (estate == sipErrorFail)
The issue is fixed for me in Cura with this. I sent a mail to the Archlinux packager so this patch can be included. Thanks |
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Cool! I not so keen on waiting, so I put a pyqt5-hotfix package with that patch into the AUR and made the cura package depend on it. 2.4.0 launches without segfault now. I think this issue can be closed. |
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We'll upgrade to PyQt 5.8 when we're ready. Until then, Arch users can compile with 5.8 themselves or use our builds with 5.7. |
Arch Linux, cura built from AUR after complete removal from system including user cache and config. dependencies also rebuilt.
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