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

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From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: jixiuf <jixiuf <at> qq.com>, 45619 <at> debbugs.gnu.org
Subject: bug#45619: 28.0.50; pcase-let on MacOS doesn't work
Date: Mon, 04 Jan 2021 20:50:54 +0100

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

> It's messier than that: the issue is that it doesn't bind variables
> which aren't used lexically (this is needed to avoid spurious warnings
> about unused vars when the var is used in on place but not in
> another).

Ok, so this "works":

(pcase-let ((`(,default-directory) '("/tmp/")))
  (ignore default-directory)
  (call-interactively 'find-file))

and also this:

(pcase-let ((default-directory "/tmp/"))
  (call-interactively 'find-file))

I wonder what is messier: the warnings or the semantics resulting from
avoiding the warnings.  I guess people would more often complain about
the warnings...

Michael.

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