Development instructions lead to a dead end
In the GNOME Shell Wiki, the Getting Started section has a helpful link saying "First, you'll need to build and run the GNOME Shell on your system":
https://wiki.gnome.org/Projects/GnomeShell/Development
That link points to Newcomers/BuildSystemComponent. Unfortunately, that page currently has the following text about halfway through:
In case you are trying to develop integrated components such as GNOME Shell, GDM, gnome-session or gnome-keyring, these are more difficult and not yet supported…
https://wiki.gnome.org/Newcomers/BuildSystemComponent
So, it would be lovely if the first wiki page had some detail about how people deal with that :)