Following a commit for Issue #1153, g-branden-robinson commented:
> Mac OS X stayed on _groff_ 1.19.2 for over a decade (presumably due to
> _groff_ 1.20 adopting to GNU GPLv3), until finally dropping _groff_
> altogether for macOS Ventura (2022).
>
> There _has_ been an interface change in that time. The [`-P` option I
> advised about is new to _groff_ 1.23.0 (July 2023)]
> (https://git.savannah.gnu.org/cgit/groff.git/tree/NEWS?h=1.23.0#n86).
> [...]
>
> There is a significant number of _groff_ users via Homebrew (enough that
> we hear from them occasionally via bug reports). Some of these have
> upgraded to 1.23.0 via that mechanism.
> [...]
>
> `nroff -` is not necessary with any _nroff_ known to me; like many other
> Bell Labs Unix programs, it reads from the standard input stream by default
> if not given any operands.
Action taken:
1. Remove the unnecessary ' -' from the nroff command in Makefile.doc.
2. In the misc.370 file containing make snippets to include, test whether
groff >= 1.23, and only insert the -P option for 1.23 or greater.
rename hints/include/multiw-3.370 to hints/include/misc.370
keep the portable nroff options in sys/unix/Makefile.doc,
and relocate the non-portable bits to a variable defined
in sys/unix/hints/include/misc.370
This assumes that the groff options are compatible between
Linux and macOS implementations of groff.
If that turns out not to be the case, this bit:
ifneq "$(NROFFISGROFF)" "" # It's groff
# add the groff-specific plain text flags
MORE_MAN2TXT_FLAGS += -Tascii -P -cbou
endif
should relocate from sys/unix/hints/include/misc.370
to sys/unix/hints/linux.370 and sys/unix/hints/macOS.370,
immediately following the inclusion of misc.370, and the
appropriate platform-specific groff options can be
adjused in whichever of those appropriately needs it.
Closes#1153
