Motivated by the recent code update of qmljs from QtCreator, which uses at least one feature that needs 5.8 (QT_CONFIG cpp macro), it might be time to consider an update of the min versions we require for Qt and KF.

Looking at interesting non-rolling-release systems where Qt & KF are part of the system there are at least:

• Ubuntu LTS 18.04: Qt 5.9, KF 5.44
• openSUSE Leap 15.0: Qt 5.9(fixed), KF 5.45

Any other platforms where Qt & KF are part of the system and which we want to support for building KDevelop from source with what is in-the-box?

Debian Stretch (current stable release) has Qt 5.7 and KF 5.28. Next stable release isn't until mid-2019.

I don't know whether supporting such a slow release cycle is worthwhile.

+1
Yes please...

Disclaimer: I'm pretty conservative when it comes to bumping version requirements of dependent packages. So far we don't get a lot by bumping the versions, quite the contrary we rather lose (potential, I know, but still) contributors b/c they cannot build KDevelop on their current OS.

Keeping at least Debian Stable in the loop would make sense to me, so: Qt 5.7 and KF 5.28? We'd only lose Ubuntu 16.04 LTS (another big "market"), which is probably negligible as there's a new LTS out now.

In D16495#359725, @kfunk wrote:

Disclaimer: I'm pretty conservative when it comes to bumping version requirements of dependent packages. So far we don't get a lot by bumping the versions, quite the contrary we rather lose (potential, I know, but still) contributors b/c they cannot build KDevelop on their current OS.

Personally i fancy not supporting old versions, as it means less chance for bugs only found in older versions ;) Thus less support issues. And getting rid of if-version variants in the code also makes me feel better :) But well, hope dies last, so perhaps one day there really will be new KDevelop contributors who are otherwise stuck on very conservatively upgraded systems... ;)

Keeping at least Debian Stable in the loop would make sense to me, so: Qt 5.7 and KF 5.28? We'd only lose Ubuntu 16.04 LTS (another big "market"), which is probably negligible as there's a new LTS out now.

I would be already a bit happy with this, would allow at least some code variants to kill (and Qt 5.7 gives us native qAsConst + QOverload).
Still not enough to build current Qml/JS support, but then potential Qml users would be rather using newer Qt versions on their machine anyway, so no issues for them.

@kfunk Would you be able to update your CI to use Debian Stable, so we have at least those minimal deps covered by some automated testing?

Will be pushed once kfunk had time to update his CI service to Debian stable for master builds, so we stay covered by the CI all the time :)