Re: Small rendering difference between nroff and mandoc

[Ingo Schwarze <schwarze@usta.de>]

Salut Nicolas,

Nicolas Joly wrote on Fri, Oct 12, 2012 at 05:00:36PM +0200:

> I recently started checking for differences between nroff and mandoc
> output for the NetBSD manpages.

Nice to hear that, thanks!

> And noticed a small spacing difference
> between the tools. When a sentence ends with a macro followed by a
> punctuation mark mandoc does only output a single space character but
> nroff adds two.

Neither the groff nor the mandoc side is as simple as that.

For partial implicit block macros, mandoc does end-of-sentence (EOS)
spacing already, e.g.

  .Pq enclosed .
  following

Also, groff only does that when the punctuation mark appears isolated,
not when it appears at the end of a word, e.g.

  .\" fstat(1)
  .Ux Ns -domain.
  A unidirectional

And groff doesn't do that when the isolated mark appears in the
middle of the line.

So, it only affects certain macros, and in a non-trivial way.
In OpenBSD base, i see one single instance of this issue,
in open(2).

In any case, this is rather rare and of relatively little impact,
compared to other remaining EOS issues.  Still, it ought to be
fixed eventually.  For now, i'm adding this to

  http://mdocml.bsd.lv/cgi-bin/cvsweb/TODO?cvsroot=mdocml

 - Trailing isolated dots lack EOS for some macros.
   This cannot use mandoc_eos() because groff only does EOS 
   for isolated dots at least in some of these cases.
   Affected macros included those using in_line_eoln().
   Make sure to fix open(2) 
   without breaking fstat(1), ksh(1), tzset(3) and UKC(8).
   reported by Nicolas Joly  Fri, 12 Oct 2012 17:00:36 +0200

Yours,
  Ingo
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