Re: device-dependent warnings

[Alejandro Colomar]

On 5/7/23 03:59, G. Branden Robinson wrote:
> Hi Alex,
> 
> At 2023-05-03T00:21:33+0200, Alejandro Colomar wrote:
>> On 5/2/23 17:10, G. Branden Robinson wrote:
>>> There isn't really any such thing as a device-dependent warning,
>>> unless you count those thrown by the output driver itself, like
>>> grops(1) or grotty(1).
>>
>> No, I run the output driver separately.  I'm talking about troff(1)
>> specifically.  I'm seeing three kinds of warnings when running
>> troff -man -Tutf8:
>>
>> troff:man3/unlocked_stdio.3:123: warning [p 2, 1.8i, div '3tbd1,0', 0.3i]: 
>> cannot break line
> 
> Okay, yes, that is termed an "output warning" internally, thus the weird
> format.  But it's still not device-dependent.  Incidentally, the format
> of the extra information has long bothered me.  So I have a change
> pending for groff-next that will make the foregoing look more like:
> 
> troff:man3/unlocked_stdio.3:123: warning [page 2, 1.8i (diversion '3tbd1,0', 
> 0.3i)]: cannot break line
> 
> What would build upon this nicely would be:
> 
> 1. For the man(7) and mdoc(7) packages to set the warning scaling
>    indicator to "n" when formatting for terminals.  It's pretty useless
>    to give terminal users a measurement in inches.  They'll need to
>    learn that "n" is in screen lines, but once they have that, they
>    stand some change of locating the position on the page being griped
>    about.
> 
> 2. Revising continuous rendering to use the "infinite"[1] page length
>    approach with sudden death truncation at the end of the document.
> 
> After all the trouble I went to to get the bugs out of the existing
> continuous rendering implementation, there will be a frisson to
> deleting most of it.
> 
>> an.tmac:man4/cciss.4:164: style: blank line in input
>>
>> man4/console_codes.4:324: warning: table wider than line length minus 
>> indentation
>>
>> I noticed some are prefixed by 'an.tman:', and I understand those are
>> the CHECKSTYLE ones (or in general produced by the man(7) macro
>> package).
> 
> Yes.
> 
>> Some others are prefixed by 'troff:'
> 
> Yes, those come from the formatter, troff(1).
> 
>> and others don't have a prefix at all.
> 
> They do: the document's file name.  The document is complaining about
> itself.  You may protest that YOU didn't put that there.  And indeed you
> didn't.  You gave tbl(1) permission to do so on your behalf.

Understood.

$ make build-pre-tbl >/dev/null
$ grep 'table wider' .tmp/man/man4/console_codes.4.eqn
.  tm1 " table wider than line length minus indentation
.  tm1 " table wider than line length minus indentation
.  tm1 " table wider than line length minus indentation
.  tm1 " table wider than line length minus indentation
.  tm1 " table wider than line length minus indentation
.  tm1 " table wider than line length minus indentation
.  tm1 " table wider than line length minus indentation
.  tm1 " table wider than line length minus indentation
.  tm1 " table wider than line length minus indentation

BTW, tbl(1) doesn't accept any warnings flags.  Is this warning
unconditional?


> 
>> I inferred that there was a difference between the latter pair of
>> groups of warnings, but maybe I'm wrong.  Why is there a difference?
> 
> The reason is that tbl itself isn't complaining; the *roff code it
> generated and put into your document is.  And the reason for _that_ is
> that at the time tbl ran, there wasn't a problem.

Seems reasonable.

>  It was only when the
> page was getting formatted that your document discovered that there was
> a problem with the line length.

That's what I consider a device-dependent warning.  In HTML, there will
probably be no limits to the right margin.  In PDF and PS, the margin
will be at a point depending on the font size and paper size.  And in
UTF8 and ASCII, it will depend on LL.

It's good to know that these warnings are independent of -ww, so that
I can remove -ww from troff -Tps and still get these.

Is there any warning from troff(1) (or any of the programs; not the doc
itself) that depend on the output like this one?

Probably the following one one?

troff:man2/s390_sthyi.2:124: warning [p 2, 1.8i]: cannot adjust line

Probably the ones you call "output warnings".  Then it might be
interesting to have an "output" warning category?

> 
> You could take the same output from tbl and format it on a wider
> terminal, and the diagnostic would not be emitted because there wouldn't
> be a problem.  Remember that when tbl runs, the document has not yet
> been formatted.  tbl doesn't _know_ what the line length will be.
> 
> During the 1.23.0 development cycle I was careful to make sure all these
> diagnostics injected into the document by tbl went to the trouble of
> mentioning tables so the user might twig on to the fact that tbl was
> (indirectly) involved.  See <https://savannah.gnu.org/bugs/?59443>.

Thanks!


> 
> Regards,
> Branden
> 
> [1] not really infinite, just INT_MAX basic units long

Heh, next thing I'll try is a document that long.  ;-)

Cheers,
Alex

-- 
<http://www.alejandro-colomar.es/>
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