GNU bug report logs - #45619
No warning when pcase-let is binding dynamic variable

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Message #8 received at 45619 <at> debbugs.gnu.org (full text, mbox):

From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: jixiuf <jixiuf <at> qq.com>
Cc: 45619 <at> debbugs.gnu.org, Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: Re: bug#45619: 28.0.50; pcase-let on MacOS doesn't work
Date: Mon, 04 Jan 2021 13:44:33 +0100

jixiuf <jixiuf <at> qq.com> writes:

> (pcase-let ((`(,default-directory) '( "/tmp/")))
>     (call-interactively 'find-file))
>
> Expected behavior: Find file in "/tmp/"
> Observed behavior: Find file in "~"

AFAICT the issue here is that `pcase-let' always creates lexically
scoped bindings, even for special variables.  That can be surprising.

@Stefan, what can we do?  Document better?  Add compiler warnings?  Or
is it possible to "fix" this?

Regards,

Michael.

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