Well, I'll Just Fix Safari Myself, Then!

Posted on 2021-09-19: https://twitter.com/_saagarjha/status/1439686585100865539

This absolute madlad reverse-engineered Safari enough to fix a bug himself, wowza

@_saagarjha:

Hey Mac Safari team, I know you’re busy getting things ready for Monterey, but can you please fix the bug where Safari crashes when you try to reopen a window that has pinned tabs? I already filed FB9637329, but to make this as easy as possible I’ve already found the bug for you.

About halfway down -[BrowserWindowPersistentState initWithBrowserWindowController:encryptionProvider:skipTabStates:] you save the currently selected tab to self->_selectedUnpinnedTabIndex. The index you calculate includes all the pinned tabs…

…but at the top of -[BrowserWindowPersistentState restoreWindowContents:] you use this combined index to read from self->_tabStates, which doesn’t include pinned tabs. Sometimes, you’ll just end up selecting the wrong tab, but other times the index will be out of bounds…

…and I’m sure you have enough crash reports for this already to recognize what the consequences of that are. Now, I don’t have your code in front of me, but perhaps you can fix this by not adding self.currentPinnedTabStates.count to the index when you save it.