bug#59802: 30.0.50; Checkbox button not rendered

[Eli Zaretskii]

> From: Stephen Berman <stephen.berman@gmx.net>
> Cc: manuel@ledu-giraud.fr,  59802@debbugs.gnu.org
> Date: Sun, 11 Dec 2022 23:40:38 +0100
> 
> In the *gud-emacs* buffer I typed `pp it->ascent' and then `pp
> it->descent' and the *input/output of emacs* buffers displayed this:
> 
> #<INVALID_LISP_OBJECT 0x0000000d>
> #<INVALID_LISP_OBJECT 0x00000003>

You are using "pp" (a.k.a. "pretty-print") incorrectly: it is intended
for Lisp objects, not for normal C variables.  For the latter, use just
"p", which is short for "print".