From: "João Távora" <joaotavora@gmail.com>
To: Alan Mackenzie <acm@muc.de>
Cc: Richard Stallman <rms@gnu.org>, emacs-devel <emacs-devel@gnu.org>
Subject: Re: How to cause a compiler warning?
Date: Mon, 15 Jan 2024 00:16:34 +0000 [thread overview]
Message-ID: <87v87ve9i5.fsf@gmail.com> (raw)
In-Reply-To: <ZaQKF46qVTm8P6uR@ACM> (Alan Mackenzie's message of "Sun, 14 Jan 2024 16:21:43 +0000")
Alan Mackenzie <acm@muc.de> writes:
>> Most assuredly not. This may give an incorrect file position for
>> the
>> warning.
> ...
>> Since 29.1, the correct function for a warning has been
>> byte-compile-warn-x.
>
>> Self-evidently so, of course, the 'x' standing for "correct".
>
> Something like that, yes.
I've had a better look at the 'byte-compile-warn-x' helper. I think I
understand what it does, but the docstring leaves to be desired, it says
the first argument a "source element, likely a symbol with position",
which is vague and curious nomenclature I've not seen in other Lisps.
More importantly, is there always a "source element" to give to
byte-compile-warn-x? Doesn't it depend on the case?
Many macros operate on Lisp forms and sometimes there is some obvious
good form to hook onto and presumably this form is either is a
sym-with-pos or has some such symbols inside it. Like this:
(defmacro fooing (a &rest body)
(when (eq (car-safe a) 'quote)
(byte-compile-warn-x a "don't quote me, silly"))
...)
Here, I do agree 'byte-compile-warn-x' is much better than
'byte-compile-warn', as Flymake highlights exactly the symbol in that
position. Great.
But macros are also just functions and sometimes they need to warn
because... it's Wednesday or something.
(defmacro define-foos (howmanyfoos)
(when (its-wednesday)
(byte-compile-warn "Beware code compiled on wednesdays!"))
...)
Here, 'byte-compile-warn', which makes the whole 'define-foos'
highlighted by Flymake is not only perfectly valid but also the only
viable option.
So I don't think byte-compiler-warn-x is "most assuredly" the only util
you should use. If it were, byte-compiler-warn might as well be
deprecated.
>> Anyway, what about <29 compatible code?
>
> What about it? Richard isn't working on < 29 code at the moment.
Alright, but since you were so assertive in overriding my suggestion
with a fairly new util, maybe you could comment on what to do in code
intended to work in those versions, for the benefit of others.
João
next prev parent reply other threads:[~2024-01-15 0:16 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-14 3:09 How to cause a compiler warning? Richard Stallman
2024-01-14 3:20 ` João Távora
2024-01-14 13:01 ` Alan Mackenzie
2024-01-14 15:43 ` João Távora
2024-01-14 16:21 ` Alan Mackenzie
2024-01-15 0:16 ` João Távora [this message]
2024-01-17 12:25 ` Alan Mackenzie
2024-01-17 13:40 ` João Távora
2024-01-18 12:05 ` Alan Mackenzie
2024-01-18 12:26 ` João Távora
2024-01-14 15:54 ` Ihor Radchenko
2024-01-14 16:26 ` Alan Mackenzie
2024-01-17 3:29 ` Richard Stallman
2024-01-17 11:59 ` Alan Mackenzie
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