https://phabricator.kde.org/source/krita/browse/master/3rdparty/ext_qt/ quote from Krita developers: "These patches are so essential that as soon as a Linux distribution moves to Qt 5.12, their version of Krita is utterly broken, no matter whether it’s the last stable release for Linux (4.1.18) or a build from our master branch. If you’re using Krita on Linux, you have to use the appimage." https://krita.org/en/item/april-development-update/
Please no, let's not fork Qt. Let's include the patches that are included upstream, we can stretch back-porting them if they are important but just applying random patches is unsustainable.
Yeah, why can these patches not be upstreamed into Qt itself?
Looking at https://cgit.kde.org/krita.git/tree/3rdparty/ext_qt/CMakeLists.txt - the following patches apply to Linux: https://codereview.qt-project.org/#/c/255382/ https://codereview.qt-project.org/#/c/255383/ https://codereview.qt-project.org/#/c/255384/ https://cgit.kde.org/krita.git/tree/3rdparty/ext_qt/0013-Poison-Qt-s-headers-with-a-mark-about-presence-of-En.patch
Looks like the first one has been merged and the other two are coming along. So I guess it's just a matter of getting all the rest in, then.
The Krita flatpak now bundles Qt: https://github.com/flathub/org.kde.krita/pull/26