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From: Eli Zaretskii <eliz@gnu.org>
To: Andrea Corallo <acorallo@gnu.org>
Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org,
	stefankangas@gmail.com, adam@alphapapa.net,
	arthur.miller@live.com
Subject: Re: Declaring Lisp function types
Date: Thu, 02 May 2024 09:15:34 +0300	[thread overview]
Message-ID: <8634r0oi2h.fsf@gnu.org> (raw)
In-Reply-To: <yp18r0t5jxl.fsf@fencepost.gnu.org> (message from Andrea Corallo on Wed, 01 May 2024 16:57:58 -0400)

> From: Andrea Corallo <acorallo@gnu.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,  emacs-devel@gnu.org,
>   stefankangas@gmail.com,  adam@alphapapa.net,  arthur.miller@live.com
> Date: Wed, 01 May 2024 16:57:58 -0400
> 
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
> 
> > Thanks Eli for reminding me: as mentioned earlier, I think we should
> > clarify what are the possible consequences if a type does not faithfully
> > reflect the behavior of the function.  Examples of questions that one
> > should be able to answer based on the doc:
> >
> > - Can an incorrect type affect Emacs' behavior (other than performance)?
> > - And if so, can it cause a crash?
> > - What if the type is/was right but an advice does
> >   not obey the original type of the advised function?
> >
> > The doc doesn't need to answer those questions directly, but it should
> > describe the possible effects of type annotations in enough details that
> > we can answer those questions.
> 
> Thanks, I think it should be more clear now.  I don't think we want to
> be over specific there as what the implementation does when the
> 'promise' of the declaration is not respected might change in the
> future.

The text you added says an incorrect type produces undefined behavior.
Is that true for all alternatives of calling the function:
interpreted, byte-compiled, and native-compiled, or only with some of
these?

"Undefined behavior" sounds scary, and I wonder whether it is really
accurate.  If the practical expressions of this UB are only some
specific ones, perhaps we should mention them?  For example, UB
generally means your entire system could be brought down, but I very
much doubt that this could happen due to incorrect type declaration,
could it?



  parent reply	other threads:[~2024-05-02  6:15 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-23 16:02 Declaring Lisp function types Andrea Corallo
2024-02-23 23:35 ` Adam Porter
2024-02-24  7:10   ` Eli Zaretskii
2024-02-24  8:53     ` Tomas Hlavaty
2024-02-24  9:08       ` Adam Porter
2024-02-24  9:24         ` Andrea Corallo
2024-02-24 15:13           ` Tomas Hlavaty
2024-02-24 15:21             ` Tomas Hlavaty
2024-02-24 15:24               ` Tomas Hlavaty
2024-02-24  8:56     ` Adam Porter
2024-02-24 10:03       ` Eli Zaretskii
2024-02-25  7:35         ` Adam Porter
2024-02-24  9:21   ` Andrea Corallo
2024-02-25 17:04 ` Alan Mackenzie
2024-02-25 17:15   ` Eli Zaretskii
2024-02-25 17:16   ` [External] : " Drew Adams
2024-02-26 16:25   ` Andrea Corallo
2024-02-29  3:50   ` Richard Stallman
2024-02-29  6:10     ` Adam Porter
2024-02-29  9:02     ` Andrea Corallo
2024-02-26  3:38 ` Richard Stallman
2024-02-26 16:38   ` [External] : " Drew Adams
2024-02-26 16:54     ` Eli Zaretskii
2024-02-26 17:44       ` Andrea Corallo
2024-02-26 16:52   ` Andrea Corallo
2024-02-26 18:10     ` Tomas Hlavaty
2024-03-02 21:19 ` Stefan Monnier via Emacs development discussions.
2024-03-03  9:52   ` Andrea Corallo
2024-03-03 14:52     ` Stefan Monnier
2024-03-03 17:31       ` Andrea Corallo
2024-03-03 18:13         ` Stefan Monnier
2024-03-15 16:49 ` Andrea Corallo
2024-03-15 18:19   ` Tomas Hlavaty
2024-03-15 18:38     ` Eli Zaretskii
2024-03-16 13:39       ` Tomas Hlavaty
2024-03-16 14:06         ` Eli Zaretskii
2024-03-16 14:56           ` Tomas Hlavaty
2024-03-16 15:43             ` Emanuel Berg
2024-03-16 15:44             ` Eli Zaretskii
2024-03-16 15:54               ` Emanuel Berg
2024-03-18  8:55               ` Lele Gaifax
2024-03-16  0:01   ` Adam Porter
2024-03-18  9:25     ` Andrea Corallo
2024-03-26 10:13   ` Andrea Corallo
2024-03-26 10:28     ` Christopher Dimech
2024-03-26 12:55     ` Eli Zaretskii
2024-03-26 16:46       ` Andrea Corallo
2024-04-29 17:48         ` Andrea Corallo
2024-04-29 17:55           ` Stefan Monnier
2024-04-29 18:42             ` Andrea Corallo
2024-04-30 14:55           ` Eli Zaretskii
2024-04-30 18:29             ` Stefan Monnier
2024-05-01 20:57               ` Andrea Corallo
2024-05-01 21:06                 ` Stefan Monnier
2024-05-02  6:16                   ` Eli Zaretskii
2024-05-02 10:16                   ` Andrea Corallo
2024-05-02  6:15                 ` Eli Zaretskii [this message]
2024-05-02 10:12                   ` Andrea Corallo
2024-05-02 11:15                     ` Eli Zaretskii
2024-05-02 13:20                     ` Stefan Monnier
2024-05-01 20:54             ` Andrea Corallo
2024-05-02 10:22               ` Eli Zaretskii
2024-05-02 15:18                 ` Andrea Corallo
2024-05-02 16:32                   ` Eli Zaretskii
2024-03-26 13:05     ` Mattias Engdegård
2024-03-26 13:44     ` Stefan Monnier
2024-03-26 14:28     ` Joost Kremers
2024-03-26 14:37       ` Stefan Monnier
  -- strict thread matches above, loose matches on Subject: below --
2024-03-16  7:46 Arthur Miller
2024-03-16 15:46 ` Emanuel Berg
2024-03-18  9:02 ` Andrea Corallo
2024-03-18  9:58   ` Arthur Miller

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