Heads up: Setting the Qt::WA_MacAlwaysShowToolWindow flag might cause crashes in macOS 10.13 and 10.12

kmatheussen

I don't have time to track down what really happened, so instead I just post this topic here in case anyone has problems with crashes on 10.13 and 10.12. The problem was not so notable when I used Qt 5.7.1, but when I upgraded to Qt 5.10.0, my program crashed almost instantly in 10.13 (which was good). I also got crash reports on 1012, although I wasn't able to make 10.12 crash myself.

Anyway, after A LOT of investigation, I finally found the cause, and as you see below, the backtrace isnt't much help.

4   libsystem_platform.dylib            0x00007fff60a79f5a _sigtramp   26
5   ???                                 0x000000014f3fc080 0   5624545408
6   libqcocoa.dylib                     0x0000000108ee2524 0x108eba000   165156
7   com.apple.CoreFoundation            0x00007fff3920d1ac __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__   12
8   com.apple.CoreFoundation            0x00007fff3920d09a _CFXRegistrationPost   442
9   com.apple.CoreFoundation            0x00007fff3920cde2 ___CFXNotificationPost_block_invoke   50
10  com.apple.CoreFoundation            0x00007fff391cb972 -[_CFXNotificationRegistrar find:object:observer:enumerator:]   1826
11  com.apple.CoreFoundation            0x00007fff391caa0c _CFXNotificationPost   652
12  com.apple.Foundation                0x00007fff3b2a3477 -[NSNotificationCenter postNotificationName:object:userInfo:]   66
13  com.apple.AppKit                    0x00007fff36c238c2 -[NSApplication _handleActivatedEvent:]   714
14  com.apple.AppKit                    0x00007fff36f9da39 -[NSApplication(NSEvent) sendEvent:]   2969
15  libqcocoa.dylib                     0x0000000108ee720d 0x108eba000   184845
16  com.apple.AppKit                    0x00007fff367ff28d -[NSApplication run]   812
17  libqcocoa.dylib                     0x0000000108ee4333 0x108eba000   172851
18  QtCore                              0x000000010346cc87 QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>)   325
19  QtCore                              0x00000001034707a2 QCoreApplication::exec()   276

aha_1980

@kmatheussen if you want to get it fixed, you should report the issue on bugreports.qt.io

They might ask you for a minimal reproduceable example, though.

Thanks.

kmatheussen

Yeah, maybe later. As I wrote, I don't have time now. The program is several hundred thousand lines long, and this line was in a general utility function that could have been called from a lot of places, so it's a lot of work to create a minimal example.

kmatheussen

Here's the github commit: https://github.com/kmatheussen/radium/commit/566b59629812c860bcb94a51a1808c2adbc245fc

kmatheussen

Also, I'm happy now. I don't need a fix. This is just a heads up post for others who might have the same problem.

mrjj

@kmatheussen
Good work finding it in such large program :)