There is a link to
https://wiki.gnome.org/Newcomers/BuildGnome but I can only find examples of application builds, not the shell, and I'm uncertain whether the shell has specific other requirements. The development guide page at
https://wiki.gnome.org/Projects/GnomeShell/Development refers to jhbuild, but jhbuild instructions say it's obsolete and replaced by BuildStream.
I was able to build gnome-shell with BuildStream, but have had some troubles figuring out how to run it, and am a bit unsure if that's actually supported as various old posts describe them as not yet working together.
If I do 'bst shell core/gnome-shell.bst' and try to 'gnome-shell --x11 -r' in the workspace, clutter errors out unable to find a GL driver. I'm unsure whether this is because I'm using the Nvidia proprietary drivers and they're not available inside the workspace, or whether it wouldn't work even if I figure out how to fix this. (In a pinch I can probably switch back to Nouveau temporarily, if that would work.)
Note the patch I'm working on changes both JS and C portions, so I can't just swap out the live JS.
Thanks!
-- brion