Comment 8 for bug 1403758

Trying to represent the meaningful parts of the rest of the discussion below.

<+tronical> tsdgeos: in QQmlEnginePrivate::registerBaseTypes can you insert a qDebug() << "QObject::staticMetaObject is at" <<
&QObject::staticMetaObject; ?
<+tronical> tsdgeos: if we get the wrong address there, then maybe we have a miscompilation of QtQml somehow
< tsdgeos> tronical: yeah it's wrong there
<+tronical> tsdgeos: ok, that means there's something wrong with libQt5Qml.so
< tsdgeos> removing -O2 didn't help
<+tronical> ok, that dump looks sane though
<+tronical> in particular QObject::staticMetaObject is referenced through a R_ARM_GOT32 relocation
<+tronical> can you paste the output of objdump -TRDC /path/to/unity8 ?
< tsdgeos> yes
< tsdgeos> tronical: http://paste.ubuntu.com/9570566/
<+tronical> aha!!
<+tronical> this one has indeed a copy relocation to QObject::staticMetaObject, which it shouldn't have if it's compiled with -fPIE I think

(... -fPIE is in use ...)

<+tronical> tsdgeos: _some_ source code in the unity8 sources references QObject::staticMetaObject
<+tronical> tsdgeos: in that .o file the reference to QObject::staticMetaObject should be through the procedure linkage table, but in your case it must be an absolute reference/relocation, which will cause the linker in turn to create a so-called copy relocation for unity8 as binary. I think it shouldn't have that
< tsdgeos> builddir/tests/mocks/Unity/Indicators/moc_sharedunitymenumodel.cpp: { &QObject::staticMetaObject, qt_meta_stringdata_SharedUnityMenuModel.data,
<+tronical> oh, that's just a test
<+tronical> still, ok, suppose it were valid, then the other question is why when loading the plugin that has QSortFilterProxyModelQML the reference to QObject::staticMetaObject isn't changed to point to the copy relocation
<+tronical> tsdgeos: could you try running your app with LD_DEBUG=bindings,symbols and collect the output? it's going to be a lot, so you could email it if it's too big for a paste
< tsdgeos> sent
<+tronical> tsdgeos: the ld output looks ok but I don't understand yet why the one file that has the QSortFilterProxyModelQML isn't relocated correctly
<+tronical> tsdgeos: that comes from libunity8-private.so, right?
<+tronical> tsdgeos: I have to leave. let's look at this early next year :)