EDIT: Thanks to a tip in the comments, Qt 5.6 support is restored for now. Something broke Fedora 27, though. Once Dolphin adopts Qt 5.9-specific features, I’ll proceed as originally mentioned below.
A day after I formally announced my game console emulator repository, the Dolphin Emulator guys decided to merge a patch that makes Qt 5.9 mandatory. That means Dolphin is no longer compatible with openSUSE Leap 42.3 which comes with Qt 5.6.
I take pride in myself for having a high-quality product, even if it’s just free video game stuff. Therefore my plan is this instead of simply disabling 42.3 and calling it a day:
I’ll pick the last commit before that patch and build that Dolphin revision. Then I’ll disable the 42.3 target and build the most recent version for the other distributions. That way the last 42.3-compatible binaries stay on the download server until I remove the 42.3 target entirely which will be either when Leap 15.1 gets released or maybe even earlier.
I don’t think the impact will be that big, though. For gaming it’s important anyway to migrate to new base OS anyway because of all the performance improvements that come with new kernel and Mesa versions but for now the 42.3 users are covered.