GNU bug report logs - #56739
29.0.50; `cl-psetq' and `cl-psetf' fail to recognize symbol macros

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Message #25 received at 56739 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: 56739 <at> debbugs.gnu.org, Wing Hei Chan <whmunkchan <at> outlook.com>
Subject: Re: bug#56739: 29.0.50; `cl-psetq' and `cl-psetf' fail to recognize
 symbol macros
Date: Mon, 05 Sep 2022 22:22:28 -0400

> -  (let ((p args) (simple t) (vars nil))
> +  (let ((p args) (simple t) (vars nil)
> +        (smacros (alist-get :cl-symbol-macros macroexpand-all-environment)))
>      (while p
> -      (if (or (not (symbolp (car p))) (cl--expr-depends-p (nth 1 p) vars))
> -	  (setq simple nil))
> -      (if (memq (car p) vars)
> -	  (error "Destination duplicated in psetf: %s" (car p)))
> +      (when (or (not (symbolp (car p)))
> +                (assq (car p) smacros)

This looks like a safe way to make it work when the place is
a symbol macro.

> +                (and (symbolp (nth 1 p))
> +                     (assq (nth 1 p) smacros))
> +                (cl--expr-depends-p (nth 1 p) vars))

But this doesn't look strong enough; if (nth 1 p) is (+ c c) where `c`
is a symbol macro the same problem will appear.  So the test needs to be
pushed into `cl--expr-depends-p` (probably into `cl--safe-expr-p` where
it will fix other related problems elsewhere).


        Stefan

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