macOS a11y: rebuild table model if out-of-bounds cell is requested

While it is the itemview's responsibility to keep the accessibility
bridge updated about changes in the view's structure and size, we
have experienced a number of assertions getting triggered when that
wasn't done correctly.
Instead of an assert (or hard crash in release builds), recreate the
table representation in the accessibility bridge when a cell that is
out-of-bounds for the current representation is requested. Emit a
warning message to inform widget authors, and improve the debug
message with information about the column count as well.

Amends 52c2b82082b535123c0eecafe1ec1e4e4190df2a.

Pick-to: 6.7 6.6
Change-Id: I19c20a932153268a5176d7378c485277088f10bf
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 34 insertions, 7 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm b/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
index 0f76d564cd..fdd089e72d 100644
--- a/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
+++ b/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
@@ -135,19 +135,37 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
                     if (tableInterface) {
                         auto *tableElement = [QMacAccessibilityElement elementWithInterface:table];
                         Q_ASSERT(tableElement);
-                        Q_ASSERT(tableElement->rows);
-
-                        qCDebug(lcAccessibilityTable) << "Creating cell representation for"
-                                                      << m_rowIndex << m_columnIndex
-                                                      << "in table with"
-                                                      << tableElement->rows.count << "rows";
+                        if (!tableElement->rows
+                         || int(tableElement->rows.count) <= m_rowIndex
+                         || int(tableElement->rows.count) != tableInterface->rowCount()) {
+                            qCWarning(lcAccessibilityTable)
+                                       << "Cell requested for row" << m_rowIndex << "is out of"
+                                       << "bounds for table with" << (tableElement->rows ?
+                                            tableElement->rows.count : tableInterface->rowCount())
+                                       << "rows! Resizing table model.";
+                            [tableElement updateTableModel];
+                        }
 
+                        Q_ASSERT(tableElement->rows);
                         Q_ASSERT(int(tableElement->rows.count) > m_rowIndex);
+
                         auto *rowElement = tableElement->rows[m_rowIndex];
-                        if (!rowElement->columns) {
+                        if (!rowElement->columns || int(rowElement->columns.count) != tableInterface->columnCount()) {
+                            if (rowElement->columns) {
+                                qCWarning(lcAccessibilityTable)
+                                        << "Table representation column count is out of sync:"
+                                        << rowElement->columns.count << "!=" << tableInterface->columnCount();
+                            }
                             rowElement->columns = [rowElement populateTableRow:rowElement->columns
                                                               count:tableInterface->columnCount()];
                         }
+
+                        qCDebug(lcAccessibilityTable) << "Creating cell representation for"
+                                                      << m_rowIndex << m_columnIndex
+                                                      << "in table with"
+                                                      << tableElement->rows.count << "rows and"
+                                                      << rowElement->columns.count << "columns";
+
                         rowElement->columns[m_columnIndex] = self;
                     }
                 }
@@ -223,6 +241,10 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 - (NSMutableArray *)populateTableArray:(NSMutableArray *)array role:(NSAccessibilityRole)role count:(int)count
 {
     if (QAccessibleInterface *iface = self.qtInterface) {
+        if (array && int(array.count) != count) {
+            [array release];
+            array = nil;
+        }
         if (!array) {
             array = [NSMutableArray<QMacAccessibilityElement *> arrayWithCapacity:count];
             [array retain];
@@ -253,6 +275,11 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
 - (NSMutableArray *)populateTableRow:(NSMutableArray *)array count:(int)count
 {
     Q_ASSERT(synthesizedRole == NSAccessibilityRowRole);
+    if (array && int(array.count) != count) {
+        [array release];
+        array = nil;
+    }
+
     if (!array) {
         array = [NSMutableArray<QMacAccessibilityElement *> arrayWithCapacity:count];
         [array retain];