Re: Bug in dumpdef's documentation

[Eric Blake]

On Tue, Oct 26, 2021 at 02:30:26AM +0200, 4dr14n31t0r Th3 G4m3r wrote:
> The output documented is not what you get from executing the m4 commands as
> documented. See https://www.gnu.org/software/m4/manual/m4.html#Dumpdef

Thanks for the report.  More details would have been nice (what you
think was wrong, and what you were expecting), but I can reproduce
that where the manual says:

dumpdef(`foo')
error→foo: ⇒

in practice (given the earlier definition of foo in the example), it should be:

dumpdef(`foo')
error→foo:      `Hello world.'
⇒

Looking at the source, in doc/m4.texi, there is:

@example
$ @kbd{m4 -d}
define(`foo', `Hello world.')
@result{}
dumpdef(`foo')
@error{}foo:@tabchar{}`Hello world.'
@result{}
dumpdef(`define')
@error{}define:@tabchar{}<define>
@result{}
@end example

My initial guess is that there is a bug in the texi -> html conversion
where @tabchar{} gets eaten incorrectly, resulting in the html output
omitting the rest of the intended line.  But checking just now, I see
the same problem in 'info m4' on the corresponding page, so it is not
a bug in the conversion, but in the m4.texi source itself.  Earlier in
the m4.texi, there is:

@c @tabchar{}
@c ----------
@c The testsuite expects literal tab output in some examples, but
@c literal tabs in texinfo lead to formatting issues.
@macro tabchar
@       @c
@end macro

So maybe the problem is that the macro expansion is leaving a bare @c
which then eats the rest of the line when using the macro within
@example.

I'm cc'ing the texinfo list to see if someone can figure out the
correct magic to use faster than I can.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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