Crash with QItemSelectionModel::selectedIndexes() - c++

Question

I've been searching all around for a solution to this problem and I'm starting to believe this can be a bug in the Qt function itself.
The problem is that after you call QItemSelectionModel::selectedIndexes() the program will crash when the program tries to destruct the QModelIndexList that this function returns. Before the crash, you get the following debug message:
Debug Assertion Failed!
(…)
File:
f:\dd\vctools\crt_bld\self_x86\crt\src\dbgheap.c
Line:1419
Expression:
_pFirstBlock == pHead
(…)
Here is the simplest code that will cause the problem, so you can test it by yourself:
#include <QApplication>
#include <QStringList>
#include <QStringListModel>
#include <QItemSelectionModel>
#include <QModelIndex>
#include <QModelIndexList>
#include <QListView>
#include <QItemSelectionModel>
void doSomethingWithSelection(QItemSelectionModel* selectionmodel);
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QStringList list;
list.push_back("1");
list.push_back("2");
list.push_back("3");
list.push_back("4");
QStringListModel model(list);
QListView view;
view.setModel(&model);
view.setSelectionMode(QAbstractItemView::ExtendedSelection);
QItemSelectionModel *selectionmodel = view.selectionModel();
QModelIndex first = model.index(0);
QModelIndex last = model.index(2);
QItemSelection selection(first, last);
selectionmodel->select(selection,QItemSelectionModel::Select);
doSomethingWithSelection(selectionmodel);
view.show();
return a.exec();
}
void doSomethingWithSelection(QItemSelectionModel* selectionmodel)
{
QModelIndexList indexlist = selectionmodel->selectedIndexes();
// this is what causes the error. I put this inside a function
// so the error will happen when exiting the function,
// when the program try to destroy the list nodes.
}

Answer 1

I have the exact same problem only that I am using selected rows instead of selected indexes. I narrowed it down to function exit when the internal QList in QModelIndexList tries to delete the indexes from the heap. Not sure how to fix it but I read this interesting post here and came up with this function:
QModelIndexList Class::getViewSelection(QAbstractItemView *view , int columnNumber) const
{
QModelIndexList list;
for (int row = 0; row < view->model()->rowCount(view->rootIndex()); ++row)
{
QModelIndex index = view->model()->index(row, columnNumber, view->rootIndex());
if (view->selectionModel()->isSelected(index))
list.push_back(index);
}
return list;
}
I wrote this function to get selected rows so the column parameter is the column you want the index for.

Answer 2

I had the same problem with QTreeView and accessing selectedIndexes() or anything in selectionModel().
It was fixed when I used the correct /MD compiler switch with the correct Qt libraries.
To fix the crash:
compile your code with /MDd and link with debug Qt libs (example Qt5Cored.lib
compile your code with /MD and link with release Qt libs (example Qt5Core.lib)

Answer 3

I managed to solve the problem, but right now I don’t understande why this works, yet: (I'm writing this as an answer hoping that it can help someone with the same problem)
In my Qt project, I was using a Kit with Microsoft Windows SDK for Windows 7 (7.0.7600.16385.40715) (x86) as compiler. When I changed the compiler to Microsoft Visual C++ Compiler 10.0 (x86) this code worked correctly.
As I said, I don't know why this works and if someone can explain this to me I will be happy to hear. I don't know even why Windows SDK is listed as a compiler.. it is not, is it?