From: Stefan Monnier 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: Michael Heerdegen <michael_heerdegen@web.de>,
Lars Ingebrigtsen <larsi@gnus.org>,
54079@debbugs.gnu.org
Subject: bug#54079: 29.0.50; Method dispatching eratically fails
Date: Tue, 08 Mar 2022 16:03:12 -0500 [thread overview]
Message-ID: <jwvv8wof9l9.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <YifBF8bPnZA+hzaK@ACM> (Alan Mackenzie's message of "Tue, 8 Mar 2022 20:48:23 +0000")
>> I'd expect the reverse: strip first and then eval the result.
>> Why should we not strip the form passed to `byte-compile-eval`?
> It's an edge case either way, but the form being evaluated might be a
> `byte-compile', in which case it's (much) better to leave the positions
> in place during this operation.
I don't understand the scenario you're thinking of.
Are you thinking of something like `(eval-when-compile (byte-compile ...))?
Does that ever happen in real life?
>> Does `byte-compile-top-level` already return a stripped form of code?
> Compiled code is always stripped, at least since the weekend!
OK, so no need to strip, go.
>> And why bother stripping the result of `byte-compile-eval`?
> Because it might be the result of evaluating a defun (or defvar or
> defconst).
AFAIK sympos should only appear within the compiler pipeline between the
"read" and the "emit resulting bytecode". They may be passed to various
functions and macros along the way, but I can't think of any scenario
where they'd end up returned by `(byte-compile-)eval`.
> This was the situation which gave rise to the bug.
Could you give some details about how it played out?
[ Either here or as a comment in the code. ]
>> Fundamentally, `eval` should always strip before doing its job.
> Except when what it's evaluating is a defun, defmacrro, defsubst, etc.
Why?
> Then it would be better to evaluate SWPs (which would work, since we're
> inside a compilation, where enable-symbols-with-pos has been bound).
> But here EXPANDED has been stripped before being evaluated, so I'm not
> sure what you're saying here.
I was suggesting to move the strip from the computation of `expanded` to
the `eval` call.
>> Yes, I know, it might be a bit expensive, but we should probably
>> define a local function in `bytecomp.el` which does strip+eval and use
>> that instead of `eval` (both here and in `byte-compile-eval`). WDYT?
> I don't think stripping is really all that expensive. There are one or
> two .el files in Emacs (ucs-normalize.el springs to mind) which have
> very large lists with vectors in them, yet they don't seem noticeably to
> slow down the Emacs build.
So maybe we should redefine `eval` as "strip and then eval"?
Stefan
next prev parent reply other threads:[~2022-03-08 21:03 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-21 0:12 bug#54079: 29.0.50; Method dispatching eratically fails Michael Heerdegen
2022-02-21 1:14 ` Michael Heerdegen
2022-03-04 16:12 ` Lars Ingebrigtsen
2022-02-21 3:16 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-02-21 4:21 ` Michael Heerdegen
2022-02-22 23:55 ` Michael Heerdegen
2022-02-23 0:27 ` Michael Heerdegen
2022-02-23 0:47 ` Michael Heerdegen
2022-03-04 2:08 ` Michael Heerdegen
2022-03-04 19:11 ` Alan Mackenzie
2022-03-05 16:37 ` Alan Mackenzie
2022-03-05 17:57 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-03-05 19:00 ` Alan Mackenzie
2022-03-05 23:01 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-03-05 18:19 ` Eli Zaretskii
2022-03-05 19:07 ` Alan Mackenzie
2022-03-06 2:19 ` Michael Heerdegen
2022-03-08 19:28 ` Alan Mackenzie
2022-03-08 19:53 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-03-08 20:48 ` Alan Mackenzie
2022-03-08 21:03 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2022-03-09 17:42 ` Alan Mackenzie
2022-03-09 18:06 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-03-09 20:32 ` Alan Mackenzie
2022-03-09 22:04 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-03-11 22:01 ` Alan Mackenzie
2022-03-12 4:23 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-03-13 16:49 ` Alan Mackenzie
2022-03-14 12:10 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-03-09 4:10 ` Michael Heerdegen
2022-03-09 17:29 ` Alan Mackenzie
2022-03-16 1:44 ` Michael Heerdegen
2022-03-16 11:52 ` Alan Mackenzie
2022-03-16 19:22 ` Michael Heerdegen
2022-03-17 2:58 ` Michael Heerdegen
2022-03-16 19:29 ` Alan Mackenzie
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