GNU bug report logs - #79998
31.0.50; cond*: cdr-safe seems not work but cdr-ignore can.

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

From: "Yue Yi" <include_yy <at> qq.com>
To: "Spencer Baugh via Bug reports for GNU Emacs,the Swiss army knife of text editors"
 <bug-gnu-emacs <at> gnu.org>
Subject: 31.0.50; cond*: cdr-safe seems not work but cdr-ignore can.
Date: Sat, 13 Dec 2025 19:51:08 +0800

Hello, Emacs maintainers,

In the docstring of match*, it says:

(cdr-safe PATTERN) matches PATTERN with lax checking of cdrs. That means
that ‘list' patterns do not examine the final cdr.

Based on my understanding, cdr-safe should match improper lists or
similar structures. For example:

(cond* ((match* (cdr-safe (list x y)) '(1 2 . 3)))) => nil

However, running this triggers a warning: Warning: Complex pattern
nested in constrained variable pattern

I found that using cdr-ignore, which appears in the implementation
source code, works as expected:

(cond* ((match* (cdr-ignore (list x y)) '(1 2 . 3)))) ;;=> t

I would like to ask: Is this a documentation error? Should the docstring
and other references (like the Info manual) be updated to replace
cdr-safe with cdr-ignore?

Regards.

Message #8 received at 79998 <at> debbugs.gnu.org (full text, mbox):

From: Sean Whitton <spwhitton <at> spwhitton.name>
To: 79998 <at> debbugs.gnu.org, rms <at> gnu.org
Cc: Yue Yi <include_yy <at> qq.com>
Subject: Re: bug#79998: 31.0.50; cond*: cdr-safe seems not work but
 cdr-ignore can.
Date: Mon, 15 Dec 2025 12:02:11 +0000

Hello,

On Sat 13 Dec 2025 at 07:51pm +08, Yue Yi wrote:

> In the docstring of match*, it says:
>
> (cdr-safe PATTERN) matches PATTERN with lax checking of cdrs. That means
> that ‘list' patterns do not examine the final cdr.
>
> Based on my understanding, cdr-safe should match improper lists or
> similar structures. For example:
>
> (cond* ((match* (cdr-safe (list x y)) '(1 2 . 3)))) => nil
>
> However, running this triggers a warning: Warning: Complex pattern
> nested in constrained variable pattern
>
> I found that using cdr-ignore, which appears in the implementation
> source code, works as expected:
>
> (cond* ((match* (cdr-ignore (list x y)) '(1 2 . 3)))) ;;=> t
>
> I would like to ask: Is this a documentation error? Should the docstring
> and other references (like the Info manual) be updated to replace
> cdr-safe with cdr-ignore?

Yes, it looks like Richard decided to rename cdr-safe to cdr-ignore but
missed updating the docstring.  I've looked in the mailing list archives
and didn't see anything to suggest otherwise.

Richard, would you mind confirming?  "cdr-safe" was a work-in-progress
name, and "cdr-ignore" was the name for this match* operator that you
went for in the end?

-- 
Sean Whitton

Message #11 received at 79998 <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: Sean Whitton <spwhitton <at> spwhitton.name>
Cc: 79998 <at> debbugs.gnu.org, include_yy <at> qq.com
Subject: Re: bug#79998: 31.0.50; cond*: cdr-safe seems not work but
 cdr-ignore can.
Date: Wed, 17 Dec 2025 23:12:39 -0500

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > > I would like to ask: Is this a documentation error? Should the docstring
  > > and other references (like the Info manual) be updated to replace
  > > cdr-safe with cdr-ignore?

  > Yes, it looks like Richard decided to rename cdr-safe to cdr-ignore

Yes.

                                                                        but
  > missed updating the docstring.

Oops!

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Message #16 received at 79998-done <at> debbugs.gnu.org (full text, mbox):

From: Sean Whitton <spwhitton <at> spwhitton.name>
To: Richard Stallman <rms <at> gnu.org>, 79998-done <at> debbugs.gnu.org,
 include_yy <at> qq.com
Subject: Re: bug#79998: 31.0.50; cond*: cdr-safe seems not work but
 cdr-ignore can.
Date: Thu, 18 Dec 2025 10:49:42 +0000

Version: 31.1

Hello,

On Wed 17 Dec 2025 at 11:12pm -05, Richard Stallman wrote:

> [[[ To any NSA and FBI agents reading my email: please consider    ]]]
> [[[ whether defending the US Constitution against all enemies,     ]]]
> [[[ foreign or domestic, requires you to follow Snowden's example. ]]]
>
>   > > I would like to ask: Is this a documentation error? Should the docstring
>   > > and other references (like the Info manual) be updated to replace
>   > > cdr-safe with cdr-ignore?
>
>   > Yes, it looks like Richard decided to rename cdr-safe to cdr-ignore
>
> Yes.
>
>                                                                         but
>   > missed updating the docstring.
>
> Oops!

Thanks both.  Now fixed on the master branch, and closing the bug.

-- 
Sean Whitton

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