G. Branden Robinson a8253dda00 Update Unix hints to revise groff detection ...

The existing detection logic was not working on any groff since at least
1.22.3 (November 2014), as could be seen by uncommenting the "$(info
...)" line.  The regex used to match "nroff --version" output was
insufficiently flexible.

Fixes:
$ (cd doc && rm -f Guidebook && PATH=$HOME/groff-1.22.3/usr/bin:/bin make Guidebook) | grep NROFF
NROFFISGROFF=
$ (cd doc && rm -f Guidebook && PATH=$HOME/groff-1.22.4/usr/bin:/bin make Guidebook) | grep NROFF
NROFFISGROFF=
$ (cd doc && rm -f Guidebook && PATH=$HOME/groff-1.23.0/usr/bin:/bin make Guidebook) | grep NROFF
NROFFISGROFF=
$ (cd doc && rm -f Guidebook && PATH=$HOME/groff-HEAD/usr/bin:/bin make Guidebook) | grep NROFF
NROFFISGROFF=

Use a different approach in Make to recording groff detection.  Use
"grep -c" (which is POSIX-conforming) to count the number of matches so
that we can use the contents of the Make macro `NROFFISGROFF` as a sort
of Boolean, which reads more idiomatically (in my opinion).

Further, instead of trying to lexically analyze a matched line in the
output of "nroff --version" and parse components of a version number out
of it, use GNU troff's built-in facility for extracting its minor
version number by storing the output of a tiny *roff document that
reports that datum (and nothing else).

Ignore warnings in category "scale" in any version of groff, because the
`tmac.n` macro package provokes them.

Clarify comments.

2026-02-07 05:00:22 -06:00

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