Re: WARNING: blocks badly nested: Oc breaks Op

[Jason McIntyre <jmc@kerhand.co.uk>]

On Thu, Sep 16, 2010 at 11:23:33PM +0200, Ingo Schwarze wrote:
> Hi Jason,
> 
> Jason McIntyre wrote on Sat, Sep 11, 2010 at 08:46:00AM +0100:
> 
> > hi. pfctl(8) contains this snippet:
> > 
> > 	.Xo
> > 	.Oo Fl t Ar table
> > 	.Fl T Ar command
> > 	.Op Ar address ... Oc
> > 	.Xc
> > 
> > mandoc is not happy about having a ".Op ... Oc" line and warns:
> > 
> > 	pfctl.8:56:20: WARNING: blocks badly nested: Oc breaks Op
> > 
> > but is that fair?
> 
> Yes, i implemented that warning on purpose, and i consider it fair.
> 
> The scope of the .Op macro is defined to extend to the end of the line.
> So, the code cited above
>  - first opens .Oo
>  - then opens .Op
>  - then closes .Oo (breaking .Op)
> 
> In XML, it would look like this:  <Oo> <Op> </Oo> </Op>
> 
> When the two enclosures are different, it does even matter
> with respect to rendering:
> 
>   .Oo Fl t Ar table
>   .Fl T Ar command
>   .Pq Ar address ... Oc
> 
> produces
> 
>   [-t table -T command (address ...])
> 
> in both old and new groff, and also in mandoc.
> 
> > of course i can move the Oc to a separate line, but
> > why should i?
> 
> Because then you get nice nesting:
> Then the Op is completely contained in the Oo.
> 
> I admit groff doesn't warn about bad nesting,
> but then again, groff issues very few warnings at all.
> 
> Yours,
>   Ingo

i don;t totally understand. Oo/Oc need not happen on the same line, so i
consider it fair game that i can stick Oc on the end of an Op line.

are you saying it's a limit of the parser and i shouldn;t do it?
not only does groff not warn about it, it also renders it correctly (as
does mandoc). hence my confusion that it generates a warning.

jmc
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