macOS: Work around [NSApplication setWindowsMenu:] out of bound access

The implementation of [NSApplication setWindowsMenu:] seems to look
for the last item in the menu, but doesn't guard the check for the
menu having items. Instead it guards on another array being non-empty,
and in some situation this array has items of type NSWindowMenuItem
while our window menu is empty (FB13369198).

To work around this we insert a hidden dummy item into the menu.

Fixes: PYSIDE-2525
Pick-to: 6.5 6.6
Change-Id: Iaa9dbc9454249f4eb34f8a338d0cc23685f0025a
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoamenubar.mm b/src/plugins/platforms/cocoa/qcocoamenubar.mm
index 6dce096556..72bbd9498d 100644
--- a/src/plugins/platforms/cocoa/qcocoamenubar.mm
+++ b/src/plugins/platforms/cocoa/qcocoamenubar.mm
@@ -362,6 +362,15 @@ void QCocoaMenuBar::insertWindowMenu()
     winMenuItem.hidden = YES;
 
     winMenuItem.submenu = [[[NSMenu alloc] initWithTitle:@"QtWindowMenu"] autorelease];
+
+    // AppKit has a bug in [NSApplication setWindowsMenu:] where it will resolve
+    // the last item of the window menu's itemArray, but not account for the array
+    // being empty, resulting in a lookup of itemAtIndex:-1. To work around this,
+    // we insert a hidden dummy item into the menu. See FB13369198.
+    auto *dummyItem = [[NSMenuItem alloc] initWithTitle:@"" action:nil keyEquivalent:@""];
+    dummyItem.hidden = YES;
+    [winMenuItem.submenu addItem:[dummyItem autorelease]];
+
     [mainMenu insertItem:winMenuItem atIndex:mainMenu.itemArray.count];
     app.windowsMenu = winMenuItem.submenu;