[debbugs-tracker] bug#21983: closed (emacs-25: cconv-convert makes invalid transformations on `setq' forms.)

[GNU bug Tracking System]

Your message dated 23 Nov 2015 14:13:13 -0000
with message-id <address@hidden>
and subject line Re: bug#21983: emacs-25: cconv-convert makes invalid 
transformations on `setq' forms.
has caused the debbugs.gnu.org bug report #21983,
regarding emacs-25: cconv-convert makes invalid transformations on `setq' forms.
to be marked as done.

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21983: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=21983
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> --- Begin Message ---
>
>
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> Subject: 
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> emacs-25: cconv-convert makes invalid transformations on `setq' forms.
>
>
>
>
> Date: 
>
> Sun, 22 Nov 2015 18:10:43 +0000
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>
>
>
> User-agent: 
>
> Mutt/1.5.23 (2014-03-12)
>
>
>
>
> Hello, Emacs.
>
> It is desirable for the byte compiler to detect `setq' forms with an odd
> number of arguments.
>
> However, when lexical binding is enabled, this is prevented by
> cconv-convert.  This converts a `setq' form into several single `setq's,
> and crucially, takes the liberty of supplying a nil argument to the last
> `setq' should no argument have been present.  This is a bug.
>
> Here's a patch which appears to fix the problem:
>
>
>
> diff --git a/lisp/emacs-lisp/cconv.el b/lisp/emacs-lisp/cconv.el
> index efa9a3d..4a3c273 100644
> --- a/lisp/emacs-lisp/cconv.el
> +++ b/lisp/emacs-lisp/cconv.el
> @@ -477,17 +477,19 @@ cconv-convert
>         (while forms
>           (let* ((sym (pop forms))
>                  (sym-new (or (cdr (assq sym env)) sym))
> -                (value (cconv-convert (pop forms) env extend)))
> +                (value-in-list
> +                 (and forms
> +                      (list (cconv-convert (pop forms) env extend)))))
>             (push (pcase sym-new
> -                   ((pred symbolp) `(setq ,sym-new ,value))
> -                   (`(car-safe ,iexp) `(setcar ,iexp ,value))
> +                   ((pred symbolp) `(setq ,sym-new ,@value-in-list))
> +                   (`(car-safe ,iexp) `(setcar ,iexp ,@value-in-list))
>                     ;; This "should never happen", but for variables which are
>                     ;; mutated+captured+unused, we may end up trying to `setq'
>                     ;; on a closed-over variable, so just drop the setq.
>                     (_ ;; (byte-compile-report-error
>                      ;;  (format "Internal error in cconv of (setq %s ..)"
>                      ;;          sym-new))
> -                    value))
> +                    (car value-in-list)))
>                   prognlist)))
>         (if (cdr prognlist)
>             `(progn . ,(nreverse prognlist))
>
>
>
> Because cconv-convert is written in pcase rather than elisp, I may have
> slipped up on some subtlety.  Would somebody please check I haven't.
>
> Thanks!
>
> -- 
> Alan Mackenzie (Nuremberg, Germany).
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#21983: emacs-25: cconv-convert makes invalid transformations on `setq' forms.
>
>
>
>
> Date: 
>
> 23 Nov 2015 14:13:13 -0000
>
>
>
>
> User-agent: 
>
> tin/2.3.1-20141224 ("Tallant") (UNIX) (FreeBSD/10.1-RELEASE-p16 (amd64))
>
>
>
>
> Fixed in emacs-25 branch.
>
> -- 
> Alan Mackenzie (Nuremberg, Germany).
>
>
>
> --- End Message ---