My own goal wasn’t to build GIMP from source specifically on OpenSUSE. I don’t actually even run OpenSUSE on my main computer (I run Gentoo). I was just trying to update my “how to build” instructions (for any version of Linux) by running through all the steps using OpenSUSE.
I have up-to-date Tumbleweed on the upstairs computer, and so likely I don’t even need to build json-glib at all for that computer. But some people will need to install json-glib from source on their computers, if they want to install GIMP from source. So it would be nice to know the exact commands to type, not just for OpenSUSE, but in general.
Is Meson another one of those Fedora/GNOME softwares? Wikipedia (Meson (software) - Wikipedia) says this:
GNOME has made it a goal to port its projects to Meson.[14] As of late 2017, GNOME Shell itself exclusively requires Meson after abandoning Autotools,[15] and central components like GTK+, Clutter-GTK, GLib and GStreamer can be built with Meson.[14]
Systemd relies on Meson since dropping Autotools in version 234.[16]
Efforts are made to port Xorg[17] and Mesa[18] to Meson.
Bleh.