bug#67991: 30.0.50; boundp always returns nil in format-mode-line with let* after 0fde935

[Eli Zaretskii]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: Aaron Jensen <aaronjensen@gmail.com>,  monnier@iro.umontreal.ca,
>   67991@debbugs.gnu.org
> Date: Sun, 24 Dec 2023 08:13:39 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > This one will return t:
> >
> >   (format-mode-line
> >    '(:eval (progn
> >          (defvar some-var)
> >          (let* ((some-var "some-value")
> >                 (_ (message "Bound: %S" (boundp 'some-var))))
> >            (message "Var: %S, Bound: %S" some-var (boundp 'some-var))))))
> >
> 
> Indeed. Looking at Fdefvar, one can see that a "(defvar foo)" does this
> when lexical-binding is t
> 
>     /* A simple (defvar foo) with lexical scoping does "nothing" except
>        declare that var to be dynamically scoped *locally* (i.e. within
>        the current file or let-block).  */
> 
> while it does nothing at all if lexical-binding is nil. Maybe defvar's
> doc string could give some hint to that. This sentence at least is not
> true for "(defvar SYMBOL)":
> 
>         The ‘defvar’ form also declares the variable as "special",
> so that it is always dynamically bound even if ‘lexical-binding’ is t.

Thanks, I hope I clarified the doc string now.