GNU bug report logs - #46786
28.0.50; pcase-let does not bind variables used inside macro

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Mauricio Collares <mauricio <at> collares.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 28.0.50; pcase-let does not bind variables used inside macro
Date: Thu, 25 Feb 2021 21:40:54 -0300

This testcase is a reduced version of a problem that happens in
the "matrix-client.el" package (available on alphapapa's GitHub):

(require 'cl-lib)
(require 'pcase)

(cl-macrolet
    ((message-self () `(message self)))
  (pcase-let ((`(,self ,self2) '("1" "2")))
    (message-self)))

Behavior before commit a218c9861573b5ec4979ff2662f5c0343397e3ff
("lisp/emacs-lisp/pcase.el: Don't bind unused vars in branches"):
outputs 1 to the minibuffer.

Behavior after the commit: Symbol’s value as variable is void: self

Best,
Mauricio

Message #8 received at 46786 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Mauricio Collares <mauricio <at> collares.org>
Cc: 46786 <at> debbugs.gnu.org, Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: Re: bug#46786: 28.0.50; pcase-let does not bind variables used
 inside macro
Date: Sat, 27 Feb 2021 06:08:01 +0100

Mauricio Collares <mauricio <at> collares.org> writes:

> This testcase is a reduced version of a problem that happens in
> the "matrix-client.el" package (available on alphapapa's GitHub):
>
> (require 'cl-lib)
> (require 'pcase)
>
> (cl-macrolet
>     ((message-self () `(message self)))
>   (pcase-let ((`(,self ,self2) '("1" "2")))
>     (message-self)))
>
> Behavior before commit a218c9861573b5ec4979ff2662f5c0343397e3ff
> ("lisp/emacs-lisp/pcase.el: Don't bind unused vars in branches"):
> outputs 1 to the minibuffer.
>
> Behavior after the commit: Symbol’s value as variable is void: self

I can reproduce the problem on the trunk here, too.  I've added Stefan M
to the CCs.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #11 received at 46786 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Mauricio Collares <mauricio <at> collares.org>
Cc: 46786 <at> debbugs.gnu.org, Lars Ingebrigtsen <larsi <at> gnus.org>
Subject: Re: bug#46786: 28.0.50; pcase-let does not bind variables used
 inside macro
Date: Mon, 01 Mar 2021 15:38:43 -0500

>> This testcase is a reduced version of a problem that happens in
>> the "matrix-client.el" package (available on alphapapa's GitHub):
>>
>> (require 'cl-lib)
>> (require 'pcase)
>>
>> (cl-macrolet
>>     ((message-self () `(message self)))
>>   (pcase-let ((`(,self ,self2) '("1" "2")))
>>     (message-self)))
>>
>> Behavior before commit a218c9861573b5ec4979ff2662f5c0343397e3ff
>> ("lisp/emacs-lisp/pcase.el: Don't bind unused vars in branches"):
>> outputs 1 to the minibuffer.
>>
>> Behavior after the commit: Symbol’s value as variable is void: self
>
> I can reproduce the problem on the trunk here, too.  I've added Stefan M
> to the CCs.

Indeed, this is a bug.  I reverted the commit and installed some other
attempt at silencing the corresponding spurious warnings.
Can you confirm that this fixes the problem in your original code
(i.e. matrix-client.el, IIUC)?


        Stefan

Message #14 received at 46786 <at> debbugs.gnu.org (full text, mbox):

From: Mauricio Collares <mauricio <at> collares.org>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 46786 <at> debbugs.gnu.org, Lars Ingebrigtsen <larsi <at> gnus.org>
Subject: Re: bug#46786: 28.0.50; pcase-let does not bind variables used
 inside macro
Date: Tue, 09 Mar 2021 19:30:20 -0300

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:
>
> Indeed, this is a bug.  I reverted the commit and installed some other
> attempt at silencing the corresponding spurious warnings.
> Can you confirm that this fixes the problem in your original code
> (i.e. matrix-client.el, IIUC)?

I've just received a report from a user that the fix worked great. Thank
you very much!

Best,
Mauricio

Message #19 received at 46786-done <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Mauricio Collares <mauricio <at> collares.org>
Cc: 46786-done <at> debbugs.gnu.org, Lars Ingebrigtsen <larsi <at> gnus.org>
Subject: Re: bug#46786: 28.0.50; pcase-let does not bind variables used
 inside macro
Date: Tue, 09 Mar 2021 18:57:11 -0500

> I've just received a report from a user that the fix worked great. Thank
> you very much!

Thanks for confirming, I'm glad you like it,


        Stefan

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