[BUG] ox-man: Nested markup is broken (was: [BUG] "\fC" macro in ox-man.el [9.6.15 (release_9.6.15 @ /usr/share/emacs/29.2/lisp/org/)])

[Ihor Radchenko <yantar92@posteo.net>]

"onf" <onf@disroot.org> writes:

>> What about \fC\f[CR]Lorem\fP\fP?
>
> (1) if both C and CR exist, sets Lorem in Courier
> (2) if only C or CR exists, sets font to Courier
> (3) if neither exists, does nothing
>
> To understand #2, let's assume that C is defined and CR is not. Then:
>   \fC -> set font to C
>   \f[CR] -> ignored
>   \fP -> restore previous font, set previous font to C
>   \fP -> restore previous font (back to C)
>
> It's important to understand that troff commands don't really use
> nesting or a stack as one might be used to from HTML and similar
> markup languages. That's why it's also not possible to e.g. nest
> bold and italic like this:
>   Normal \fBbold \fIbold-italic\fP bold\fP normal
>
> ...which actually gives you:
>   Normal bold italic bold italic

Yikes!

We currently implicitly rely on the assumption that things are working
differently:

    normal *bold /italic/ bold* normal

is exported as

    .TH "" "1" 
    .PP
    normal \fBbold \fIitalic\fP bold\fP normal

and the last "normal" is indeed rendered as italic.

> One has to do one of these instead:
>   Normal \fBbold \f[BI]bold-italic\fP bold\fR normal
>   Normal \fBbold \f[BI]bold-italic\fB bold\fR normal
>   Normal \fBbold\fP \f[BI]bold-italic\fP \fBbold\fP normal

I'm afraid that I'll need to rethink that export algo for ox-man to
account for this nuance.

Probably, the simplest way implementation-wise will be applying faces to
each "plain text" segment individually:

   \fRnormal \fR\fBbold \fR\f[BI]italic\fR\fB bold\fR\fR normal\fR

-- 
Ihor Radchenko // yantar92,
Org mode maintainer,
Learn more about Org mode at <https://orgmode.org/>.
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