Pierre Neidhardt <mail@ambrevar.xyz> writes:

> You are right, something is wrong with substitute-keyword-arguments.

The problem is that GLib has no configure-flags from before.  I'm not
sure why we get no error from substitute-keyword-arguments (is it
swallowed?  never run?), but if you change this part:

 (substitute-keyword-arguments (package-arguments glib)
   ((#:configure-flags flags)
    `(cons "-Dgtk_doc=true" ,flags)))

...to read like this:

 (substitute-keyword-arguments (package-arguments glib)
   ((#:configure-flags flags ''())
    `(cons "-Dgtk_doc=true" ,flags)))

Then it should work.  The difference is that "flags" gets initialized as
the empty list when not already set.