> Cc: larsi@gnus.org, daniele@grinta.net, emacs-devel@gnu.org
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Sat, 6 Jul 2019 18:16:03 -0700

As for "make -O", could it be that you were talking literally about
that, i.e. about "make -O=target"?  Because I meant "make -O=line",
which AFAIR slows down the build only slightly, and provides the
line-level separation that you want to see.  I think using that is a
good compromise.