gdm 3.29.92 doesn't compile without plymouth support
gdm-manager.c: In function ‘on_display_status_changed’:
gdm-manager.c:1480:30: error: ‘doing_initial_setup’ undeclared (first use in this function)
if (!doing_initial_setup && (status == GDM_DISPLAY_FINISHED || g_strcmp0 (session_type, "x11") == 0)) {
^~~~~~~~~~~~~~~~~~~
gdm-manager.c:1480:30: note: each undeclared identifier is reported only once for each function it appears in
I think doing_initial_setup variable is only visible with plymouth is enabled. I may be wrong of course.