GNU bug report logs - #24641
let-alist redundantly binds variables already bound by nested let-alist calls

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

From: Philipp <p.stephani2 <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 26.0.50;
 let-alist: Incorrect byte-compile warning about unused lexical
 variable
Date: Sat, 08 Oct 2016 14:43:03 +0200

$ cat /tmp/letalist.el 
;; -*- lexical-binding: t; -*-
(print
 (let-alist '((outer . ((inner . value))))
   (let-alist .outer .inner)))
   
$ emacs -Q -batch -f batch-byte-compile /tmp/letalist.el 

In toplevel form:
/tmp/letalist.el:2:1:Warning: Unused lexical variable ‘\.inner’

This warning is incorrect because '.inner' is used in the inner
let-alist form.


In GNU Emacs 26.0.50.2 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
 of 2016-10-07 built on localhost
Repository revision: 1686a0cde3d6adced3b5393945d6a9ab71b4a3c9
Windowing system distributor 'The X.Org Foundation', version 11.0.11702000
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Message #8 received at 24641 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: Philipp <p.stephani2 <at> gmail.com>
Cc: 24641 <at> debbugs.gnu.org
Subject: Re: bug#24641: 26.0.50;
 let-alist: Incorrect byte-compile warning about unused lexical
 variable
Date: Sat, 08 Oct 2016 09:09:52 -0400

retitle 24641 let-alist redundantly binds variables already bound by nested let-alist calls
severity 24641 minor
tags 24641 confirmed
quit

Philipp <p.stephani2 <at> gmail.com> writes:

> $ cat /tmp/letalist.el 
> ;; -*- lexical-binding: t; -*-
> (print
>  (let-alist '((outer . ((inner . value))))
>    (let-alist .outer .inner)))
>    
> $ emacs -Q -batch -f batch-byte-compile /tmp/letalist.el 
>
> In toplevel form:
> /tmp/letalist.el:2:1:Warning: Unused lexical variable ‘\.inner’
>
> This warning is incorrect because '.inner' is used in the inner
> let-alist form.

The byte compiler warning correct, the problem is in let-alist: both the
outer and inner let-alist calls let-bind '.inner'.  Here is the
macroexpansion:

(let
    ((#1=#:alist
      '((outer
         (inner . value)))))
  (let
      ((\.outer
        (cdr
         (assq 'outer #1#)))
       (\.inner ; <------------ this one is unused
        (cdr
         (assq 'inner #1#))))
    (let
        ((#2=#:alist \.outer))
      (let
          ((\.inner
            (cdr
             (assq 'inner #2#))))
        \.inner))))

Message #17 received at 24641 <at> debbugs.gnu.org (full text, mbox):

From: Philipp Stephani <p.stephani2 <at> gmail.com>
To: 24641 <at> debbugs.gnu.org
Subject: Re: bug#24641: 26.0.50; let-alist: Incorrect byte-compile warning
 about unused lexical variable
Date: Sat, 08 Oct 2016 13:33:20 +0000

[Message part 1 (text/plain, inline)]

Philipp <p.stephani2 <at> gmail.com> schrieb am Sa., 8. Okt. 2016 um 14:48 Uhr:

>
>
> $ cat /tmp/letalist.el
>
> ;; -*- lexical-binding: t; -*-
>
> (print
>
>  (let-alist '((outer . ((inner . value))))
>
>    (let-alist .outer .inner)))
>
>
>
> $ emacs -Q -batch -f batch-byte-compile /tmp/letalist.el
>
>
>
> In toplevel form:
>
> /tmp/letalist.el:2:1:Warning: Unused lexical variable ‘\.inner’
>
>
>
> This warning is incorrect because '.inner' is used in the inner
>
> let-alist form.
>
>
>
>
I've attached a patch.

[Message part 2 (text/html, inline)]

[0001-Don-t-consider-nested-let-alist-forms.txt (text/plain, attachment)]

Message #20 received at 24641 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: Philipp Stephani <p.stephani2 <at> gmail.com>
Cc: 24641 <at> debbugs.gnu.org
Subject: Re: bug#24641: 26.0.50;
 let-alist: Incorrect byte-compile warning about unused lexical
 variable
Date: Sat, 08 Oct 2016 10:35:28 -0400

Philipp Stephani <p.stephani2 <at> gmail.com> writes:
>
> I've attached a patch.

Looks good to me.

Message #23 received at 24641 <at> debbugs.gnu.org (full text, mbox):

From: Philipp Stephani <p.stephani2 <at> gmail.com>
To: npostavs <at> users.sourceforge.net
Cc: 24641 <at> debbugs.gnu.org
Subject: Re: bug#24641: 26.0.50; let-alist: Incorrect byte-compile warning
 about unused lexical variable
Date: Sat, 08 Oct 2016 16:37:38 +0000

[Message part 1 (text/plain, inline)]

<npostavs <at> users.sourceforge.net> schrieb am Sa., 8. Okt. 2016 um 16:34 Uhr:

> Philipp Stephani <p.stephani2 <at> gmail.com> writes:
>
> >
>
> > I've attached a patch.
>
>
>
> Looks good to me.
>
>
Thanks, pushed to master.

[Message part 2 (text/html, inline)]

Message #30 received at 24641 <at> debbugs.gnu.org (full text, mbox):

From: Mark Oteiza <mvoteiza <at> udel.edu>
To: Philipp Stephani <p.stephani2 <at> gmail.com>
Cc: 24641 <at> debbugs.gnu.org, npostavs <at> users.sourceforge.net
Subject: Re: bug#24641: 26.0.50;
 let-alist: Incorrect byte-compile warning about unused lexical
 variable
Date: Sun, 09 Oct 2016 16:51:42 -0400

Philipp Stephani <p.stephani2 <at> gmail.com> writes:

> <npostavs <at> users.sourceforge.net> schrieb am Sa., 8. Okt. 2016 um 16:34 Uhr:
>
>  Philipp Stephani <p.stephani2 <at> gmail.com> writes:
>
>  > I've attached a patch.
>
>  Looks good to me.
>
> Thanks, pushed to master. 

The package version should probably get bumped, WDYT?

Message #33 received at 24641 <at> debbugs.gnu.org (full text, mbox):

From: Philipp Stephani <p.stephani2 <at> gmail.com>
To: Mark Oteiza <mvoteiza <at> udel.edu>
Cc: 24641 <at> debbugs.gnu.org, npostavs <at> users.sourceforge.net
Subject: Re: bug#24641: 26.0.50; let-alist: Incorrect byte-compile warning
 about unused lexical variable
Date: Sat, 15 Oct 2016 20:24:41 +0000

[Message part 1 (text/plain, inline)]

Mark Oteiza <mvoteiza <at> udel.edu> schrieb am So., 9. Okt. 2016 um 22:51 Uhr:

> Philipp Stephani <p.stephani2 <at> gmail.com> writes:
>
> > <npostavs <at> users.sourceforge.net> schrieb am Sa., 8. Okt. 2016 um 16:34
> Uhr:
> >
> >  Philipp Stephani <p.stephani2 <at> gmail.com> writes:
> >
> >  > I've attached a patch.
> >
> >  Looks good to me.
> >
> > Thanks, pushed to master.
>
> The package version should probably get bumped, WDYT?
>

Maybe, is there a policy for this? IIUC now that let-alist is part of Emacs
core we don't care about package versions any more?

[Message part 2 (text/html, inline)]

Message #40 received at 24641 <at> debbugs.gnu.org (full text, mbox):

From: Mark Oteiza <mvoteiza <at> udel.edu>
To: Philipp Stephani <p.stephani2 <at> gmail.com>
Cc: 24641 <at> debbugs.gnu.org, npostavs <at> users.sourceforge.net
Subject: Re: bug#24641: 26.0.50; let-alist: Incorrect byte-compile warning
 about unused lexical variable
Date: Thu, 26 Jan 2017 11:13:21 -0500

On 15/10/16 at 08:24pm, Philipp Stephani wrote:
> Mark Oteiza <mvoteiza <at> udel.edu> schrieb am So., 9. Okt. 2016 um 22:51 Uhr:
> > The package version should probably get bumped, WDYT?
> 
> Maybe, is there a policy for this? IIUC now that let-alist is part of Emacs
> core we don't care about package versions any more?

As long as it lives in ELPA and supports older emacs, we should care.
Since it was a bug in let-alist, I'm inclined to bump it (to 1.0.5).

(I just came across some let-alist stuff written oddly because of the
original bug, hence the necrobump)

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