GNU bug report logs - #65833
30.0.50; cl-loop on the intervals uses global var

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: bug#65833: closed (Re: bug#65833: 30.0.50; cl-loop on the
 intervals uses global var)
Date: Sat, 09 Sep 2023 02:19:02 +0000

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Your bug report

#65833: 30.0.50; cl-loop on the intervals uses global var

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 65833 <at> debbugs.gnu.org.

-- 
65833: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=65833
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: help-debbugs <at> gnu.org (GNU bug Tracking System)
Cc: 65833-done <at> debbugs.gnu.org
Subject: Re: bug#65833: 30.0.50; cl-loop on the intervals uses global var
Date: Fri, 08 Sep 2023 22:18:29 -0400

I pushed a fix for it to `master`.


        Stefan

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From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: bug-gnu-emacs <at> gnu.org
Subject: 30.0.50; cl-loop on the intervals uses global var
Date: Fri, 08 Sep 2023 16:57:18 -0400

Package: Emacs
Version: 30.0.50


    ELISP> (macroexpand '(cl-loop for X being the intervals of B do
                           (FOO)))
    (cl--block-wrapper
     (catch '--cl-block-nil--
       (cl-block --cl-finish--
         (cl--map-intervals
          (lambda (--cl-var1-- --cl-var2--)
            (setq X (cons --cl-var1-- --cl-var2--))
            (FOO))
          B nil nil nil))
       nil))

As you can see, this sets fails to declare `X` as being a local
variable, so it will affect `X` from the surrounding context.

This looping form doesn't exist in Common Lisp, but `for X being` never
behaves like that, so this is clearly a bug.


        Stefan

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