From: "Basil L. Contovounesios" via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: Alan Mackenzie <acm@muc.de>
Cc: "Mattias Engdegård" <mattiase@acm.org>,
"Stefan Monnier" <monnier@iro.umontreal.ca>,
58601@debbugs.gnu.org
Subject: bug#58601: 29.0.50; Infinite loop in byte-compile--first-symbol-with-pos
Date: Fri, 21 Oct 2022 13:47:53 +0300 [thread overview]
Message-ID: <871qr1tpuu.fsf@tcd.ie> (raw)
In-Reply-To: <Y0+6ut4tMTyG0j4u@ACM> (Alan Mackenzie's message of "Wed, 19 Oct 2022 08:52:10 +0000")
Alan Mackenzie [2022-10-19 08:52 +0000] wrote:
> On Tue, Oct 18, 2022 at 15:19:35 -0400, Stefan Monnier wrote:
>> >> That's not the problem, because it's just for illustrative purposes.
>> >> Instead of 'arg' being passed unchanged as the FORM argument, it could
>> >> just as well have been `(my-frobnicate ,arg).
>
>> > That would not loop, since there is a symbol with position there.
>
>> BTE, the real-world use case is a compiler macro which takes the list of
>> args and tucks the name of another function in front. So the generated
>> code, passed to `macroexp-warn-and-return` has the shape
>
>> (somefun somearg1 somearg2)
>
>> where `somefun` does *not* come from the source but from the
>> compiler-macro instead and hence doesn't have any sympos, and then
>> `somearg1` was an expression of the form
>
>> (quote #1=(1 2 3 . #1#))
>
>> So, there was no cycle in the code part, the cycle is only inside the
>> data embedded in the code.
>
> I think somebody who writes something like that _deserves_ to go into an
> infinite loop. Have you ever seen anything at all like this in real
> life?
See some of the recent commits listed in my other message.
--
Basil
next prev parent reply other threads:[~2022-10-21 10:47 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-17 23:24 bug#58601: 29.0.50; Infinite loop in byte-compile--first-symbol-with-pos Basil L. Contovounesios via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-18 14:51 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-18 16:33 ` Basil L. Contovounesios via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-18 19:19 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-18 15:01 ` Alan Mackenzie
2022-10-18 16:18 ` dick
2022-10-18 16:34 ` Basil L. Contovounesios via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-18 17:06 ` Alan Mackenzie
2022-10-18 17:39 ` dick
2022-10-18 19:19 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-19 8:52 ` Alan Mackenzie
2022-10-19 12:48 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-10-21 10:57 ` Mattias Engdegård
2022-10-21 10:47 ` Basil L. Contovounesios via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2022-10-21 10:47 ` Basil L. Contovounesios via Bug reports for GNU Emacs, the Swiss army knife of text editors
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