When I build Emacs I want some additional major modes to be part of the build.
Previously I just put the additional mode files in \lisp\progmodes and rebuild.
I pretty much always just do a BOOTSTRAP build.
Something has changed in the last month or two because this doesn't work any
more.
loaddefs.el *does* contain the autoload commands for the new modes but Emacs
doesn't recognize the mode commands.
If I manually do (load "loaddefs") then it works.
Sounds like Emacs uses loaddefs.el that's just a copy of
ldefs-boot.el. The question is, why?
Can you post a full transcript of a "make bootstrap" session?