From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Alan Mackenzie <acm@muc.de>
Cc: emacs-devel@gnu.org
Subject: Re: Help sought: Details of byte-compile-make-closure, please.
Date: Tue, 17 May 2022 08:33:09 -0400 [thread overview]
Message-ID: <jwvczgc9wsc.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <YoNnuXhb+eGgGzX9@ACM> (Alan Mackenzie's message of "Tue, 17 May 2022 09:15:37 +0000")
Alan Mackenzie [2022-05-17 09:15:37] wrote:
> Whilst fixing bug #55323, I came across more places in the byte compiler
> where we might need to strip positions from symbols.
[ Sidenote: I don't understand why you'd need to strip the positions
manually here. Is it for the `(apply #'make-byte-code ...` case,
because your later position-stripping code doesn't recurse within
byte-code functions? ]
> (i) Does byte-compile-make-closure get called at all when
> lexical-binding is nil?
No.
> (ii) Is the ARG argument to make-byte-code, extracted from the parameter
> FORM always in the bit-encoded form (7 bits for minimum args, 7 bits for
> maximum args and 1 bit for &rest), or might it sometimes be an "old
> fashioned" list of symbols?
It's never the "old fashioned" list of symbols, because that's only
used for lexical-binding==nil functions as you can see in
`byte-compile-lambda` where we do:
(apply #'make-byte-code
(if lexical-binding
(byte-compile-make-args-desc arglist)
bare-arglist)
> I need to know this because such a list
> might need positions stripping from these symbols.
Indeed.
> (iii) Is there ever a non-null interactive form contained in the
> parameter FORM?
Usually not, but sometimes yes.
> (If so, it comes in in a &rest parameter and is
> forwarded to make-byte-code in an &optional argument.) Such an
> interactive form may need positions stripping from its symbols too.
FWIW, I think that is `byte-compile-lambda` strips the positions then
`byte-compile-make-closure` won't need to (since all the args, constant
vector, interactive form, ... comes from the byte code returned by
`byte-compile-make-closure`).
Oh, actually not quite: the `docstring-exp` needs to be stripped before
passing it to `eval`.
Stefan
prev parent reply other threads:[~2022-05-17 12:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-17 9:15 Help sought: Details of byte-compile-make-closure, please Alan Mackenzie
2022-05-17 12:04 ` Eli Zaretskii
2022-05-17 12:33 ` Stefan Monnier [this message]
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