Re: Bullets everywhere

[Ingo Schwarze <schwarze@usta.de>]

Hi Ulrich,

Ulrich Spoerlein wrote on Mon, Jan 10, 2011 at 11:11:10PM +0100:

> prompted by some gratuitous differences in groff vs mandoc output, I
> wanted to ask for the rationale here (if any).
> 
> .Bl -bullet
> .It 
> one
> .El
> 
> will print the following raw output:
> 
> mandoc:            o^Ho   one
> groff[1] -Tascii:  +^H+^Ho^Ho   one
> groff[1] -Tutf8:   ·^H·   one
> groff[2] -Tascii:  ^[[1m+^Ho   ^[[22mone
> 
> [1] is groff 1.19.2 (the last GPLv2 release)
> [2] is groff 1.20.1

We don't do -Tutf8, so that part is not relevant.

Regarding groff-1.20.1 (which i'm using as my reference groff, too),
you should always use

  /usr/local/bin/nroff -c -mandoc -Tascii

which will produce "+\b+\bo\bo" just like groff-1.19.2 (though i
admit i never tried 1.19, i only use 1.15 and 1.20).

Indeed, i have been regarding that difference as annoying for a long
time.  It is one of the main sources of noise in automatic comparisons,
so it is a real hindrance when trying to find bugs, and even worse,
when making sure to prevent regressions.  For example, fixing it
reduces the size of the /usr/src/bin diff from over 1000 to less
than 600 lines.

Even if terminals capable of showing two glyphs on top of each other
are probably rare nowadays, so "+\b+\bo\bo" vs. "o\bo" will rarely
make a noticable difference for the user, i strongly feel like
committing the following diff, just for binary compatibility.

At some point in the past, Kristaps voiced concerns that a similar
but less elegant diff i sent out might wreak havoc in the terminal
frontends because term.c / term_flushln() would rely on the fact
that backspace only occurs in the usual underline and bold sequences,
not as a standalone character.  Actually, this is not an issue.
The only guarantee needed by term_flushln() is that you don't go
back more than you advanced, so the diff poses no risk.
Besides, the diff also works fine with term.c / encode().
When processing "+\bo", the plus will be encoded, the backspace
passed through, and the circle encoded, just as we want it,
to produce "+\b+\bo\bo" or "_\b+\b_\bo".

So, do you agree with this diff?
It survived an OpenBSD build, and the output looks good.

> HTML for mandoc 1.10.9:
> Postscript!

No comment on my part.  :)

Yours,
  Ingo


Index: chars.in
===================================================================
RCS file: /cvs/src/usr.bin/mandoc/chars.in,v
retrieving revision 1.13
diff -u -p -r1.13 chars.in
--- chars.in	20 Sep 2010 20:43:38 -0000	1.13
+++ chars.in	23 Jan 2011 14:32:06 -0000
@@ -387,7 +387,7 @@ CHAR("rs",			"\\",		92)
 
 /* Text markers. */
 CHAR("ci",			"o",		9675)
-CHAR("bu",			"o",		8226)
+CHAR("bu",			"+\bo",		8226)
 CHAR("dd",			"=",		8225)
 CHAR("dg",			"-",		8224)
 CHAR("lz",			"<>",		9674)
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