Feedback sought on unusual arithmetic expressions

"G. Branden Robinson" <[email protected]> Sun, 22 Mar 2026 19:01:52 -0500

Newsgroups	gmane.comp.printing.groff.general
Message-ID	<20260323000152.bi6ay5prwnjdrsuf@illithid>

Hi folks,

Back in January I filed Savannah #67908,[1] and immediately postponed it
because dealing with it was not timely giving the C/C++ code freeze then
in effect (or soon to be).

In it, I wrote:

---snip---
Pointed out by Ingo Schwarze in a recent mandoc commit.[2]

He spoke of the `ll` request but it's true in general for numeric
expressions.

    .nr a +-+-1
    .tm a=\na
    .nr b +-+2
    .tm b=\nb

...reports "a=1" and "b=-2" on GNU, DWB 3.3, Heirloom Doctools, and Plan
9 from User Space _troff_s.

This convention is a little weird.

But, as Ingo points out, it can get weirder when a numeric expression
can be preceded by a unary incrementation or decrementation
operator...which happens to be spelled the same.

Should we:

1.  Have the formatter throw a warning when multiple sign operators
    occur in sequence?

2.  Have the formatter throw a warning when a *crementation operator is
    followed by a sign operator?

Nothing seems to be breaking due to this, so setting severity to "wish".

Requesting feedback from the community; setting to "Need Info" status.
---end snip---

Please follow up with your thoughts here or to the ticket.

Regards,
Branden

[1] https://savannah.gnu.org/bugs/?67908
[2] https://cvsweb.bsd.lv/mandoc/term.c?rev=1.295&content-type=text/x-cvsweb-markup&sortby=date

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