bug#18059: 24.3.92; defvar and special variables

[Noam Postavsky]

Stefan Monnier <monnier@IRO.UMontreal.CA> writes:

>> I noticed doing (let () (defvar x)) seems to be the same as (progn
>> (defvar x)), which may be a bug.
>
> Both interpretations would make sense, so given the lack of
> documentation about the intention, we could consider it as a feature as
> much as a bug.
>
> Have you checked whether the behavior is the same with the
> byte-compiler?

Yes, it's the same.

I see that a lambda form scopes the defvar even if it has no parameters
though.  I.e., the following prints 1:


    ;; -*- lexical-binding: t -*-

    (lambda ()
      (defvar x))

    (let ((x 1))
      (setq testfun (lambda () x)))

    (message "%S" (funcall testfun))