From: Michael Heerdegen via "Emacs development discussions." <emacs-devel@gnu.org>
To: emacs-devel@gnu.org
Subject: Re: pcase generates an unprintable expansion for a form in test erc--restore-initialize-priors
Date: Sun, 26 May 2024 23:19:16 +0200 [thread overview]
Message-ID: <87ed9oe0ff.fsf@web.de> (raw)
In-Reply-To: ZlNVi8k59lVzkbnV@ACM
Alan Mackenzie <acm@muc.de> writes:
> The form being compared using pcase, although not tiny, is not all that
> big, and it would be easy to increase its size to cause it to violate any
> reasonable value of PRINT_CIRCLE.
Even worse: if you try to compile a file consisting of only this defun
(this is exactly one part of that test factored out):
#+begin_src emacs-lisp
(defun erc--restore-initialize-priors-1 (expansion)
(pcase expansion
(`(let* ((,p (or erc--server-reconnecting erc--target-priors))
(,q (and ,p (alist-get 'erc-my-mode ,p))))
(unless (local-variable-if-set-p 'erc-my-mode)
(error "Not a local minor mode var: %s" 'erc-my-mode))
(setq foo (if ,q (alist-get 'foo ,p) (ignore 1 2 3))
bar (if ,q (alist-get 'bar ,p) #'spam)
baz (if ,q (alist-get 'baz ,p) nil)))
t)))
#+end_src
with a slightly reduced `max-lisp-eval-depth' (from 1600 to 1000)
compilation fails.
> Would it be possible and a good idea to amend pcase such that it
> generates less deeply nested expansions for forms such as we have here?
I think this todo in pcase.el is related:
;; - try and be more clever to reduce the size of the decision tree, and
;; to reduce the number of leaves that need to be turned into functions:
> Or does anybody have any ideas how better to resolve the problem?
Apart from trying to work around it somehow, I don't.
Michael.
next prev parent reply other threads:[~2024-05-26 21:19 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-26 15:30 pcase generates an unprintable expansion for a form in test erc--restore-initialize-priors Alan Mackenzie
2024-05-26 21:19 ` Michael Heerdegen via Emacs development discussions. [this message]
2024-05-27 17:39 ` Stefan Monnier
2024-05-27 18:23 ` Stefan Monnier
2024-05-27 19:29 ` Michael Heerdegen via Emacs development discussions.
2024-05-27 19:42 ` Stefan Monnier
2024-05-29 15:39 ` Michael Heerdegen
2024-05-30 23:43 ` Stefan Monnier
2024-05-31 7:32 ` Andrea Corallo
2024-05-31 12:45 ` Stefan Monnier
2024-06-03 17:42 ` Stefan Monnier
2024-06-04 0:57 ` Michael Heerdegen
2024-05-27 20:14 ` F. Jason Park
2024-05-27 22:31 ` Stefan Monnier
2024-05-30 23:45 ` Stefan Monnier
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