From ecef7046245f3adee9366d3543e4ed2a09f65735 Mon Sep 17 00:00:00 2001
From: Volker Hilsheimer <volker.hilsheimer@qt.io>
Date: Fri, 8 Dec 2023 16:53:51 +0100
Subject: [PATCH] QComboBox: inform accessibility about model change before
 selecting
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QComboBox implicitly selects the first item that gets inserted into the
model. This happens in response to the model's rowInserted signal, at
which point the item view might not have handled the rowInserted signal
yet. Because of that, the view couldn't update the accessibility bridge,
so informing accessibility about a row being selected that doens't exist
in the bridge's representation of the table yet will result in data
being out of sync, and depending on the bridge implementation trigger
asserts.

Fix this by explicitly updating the accessibility bridge before
implicitly selecting the first row.

Fixes: QTBUG-119526
Fixes: QTBUG-118585
Pick-to: 6.6 6.5
Change-Id: I2830c00751b3f18feb5d9252b23823c80229fed1
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
---
 .../platforms/cocoa/qcocoaaccessibilityelement.mm     | 11 +++++++++++
 src/widgets/widgets/qcombobox.cpp                     | 11 +++++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm b/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
index 9e33b43342c..0f76d564cdf 100644
--- a/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
+++ b/src/plugins/platforms/cocoa/qcocoaaccessibilityelement.mm
@@ -9,12 +9,15 @@
 #include "qcocoawindow.h"
 #include "qcocoascreen.h"
 
+#include <QtCore/qlogging.h>
 #include <QtGui/private/qaccessiblecache_p.h>
 #include <QtGui/private/qaccessiblebridgeutils_p.h>
 #include <QtGui/qaccessible.h>
 
 QT_USE_NAMESPACE
 
+Q_LOGGING_CATEGORY(lcAccessibilityTable, "qt.accessibility.table")
+
 using namespace Qt::Literals::StringLiterals;
 
 #if QT_CONFIG(accessibility)
@@ -133,6 +136,12 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
                         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";
+
                         Q_ASSERT(int(tableElement->rows.count) > m_rowIndex);
                         auto *rowElement = tableElement->rows[m_rowIndex];
                         if (!rowElement->columns) {
@@ -275,6 +284,8 @@ static void convertLineOffset(QAccessibleTextInterface *text, int *line, int *of
     if (QAccessibleInterface *iface = self.qtInterface) {
         if (QAccessibleTableInterface *table = iface->tableInterface()) {
             Q_ASSERT(!self.isManagedByParent);
+            qCDebug(lcAccessibilityTable) << "Updating table representation with"
+                                          << table->rowCount() << table->columnCount();
             rows = [self populateTableArray:rows role:NSAccessibilityRowRole count:table->rowCount()];
             columns = [self populateTableArray:columns role:NSAccessibilityColumnRole count:table->columnCount()];
         }
diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index 2e60d1f552b..b766595d839 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -1128,6 +1128,17 @@ void QComboBoxPrivate::rowsInserted(const QModelIndex &parent, int start, int en
     // set current index if combo was previously empty and there is no placeholderText
     if (start == 0 && (end - start + 1) == q->count() && !currentIndex.isValid() &&
         placeholderText.isEmpty()) {
+#if QT_CONFIG(accessibility)
+        // This might have been called by the model emitting rowInserted(), at which
+        // point the view won't have updated the accessibility bridge yet about its new
+        // dimensions. Do it now so that the change of the selection matches the row
+        // indexes of the accessibility bridge's representation.
+        if (container && container->itemView()) {
+            QAccessibleTableModelChangeEvent event(container->itemView(),
+                                                   QAccessibleTableModelChangeEvent::ModelReset);
+            QAccessible::updateAccessibility(&event);
+        }
+#endif
         q->setCurrentIndex(0);
         // need to emit changed if model updated index "silently"
     } else if (currentIndex.row() != indexBeforeChange) {