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bug#54079: 29.0.50; Method dispatching eratically fails
From: |
Stefan Monnier |
Subject: |
bug#54079: 29.0.50; Method dispatching eratically fails |
Date: |
Tue, 08 Mar 2022 16:03:12 -0500 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
>> 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
- bug#54079: 29.0.50; Method dispatching eratically fails, (continued)
- bug#54079: 29.0.50; Method dispatching eratically fails, Alan Mackenzie, 2022/03/05
- bug#54079: 29.0.50; Method dispatching eratically fails, Eli Zaretskii, 2022/03/05
- bug#54079: 29.0.50; Method dispatching eratically fails, Michael Heerdegen, 2022/03/05
- bug#54079: 29.0.50; Method dispatching eratically fails, Alan Mackenzie, 2022/03/08
- bug#54079: 29.0.50; Method dispatching eratically fails, Stefan Monnier, 2022/03/08
- bug#54079: 29.0.50; Method dispatching eratically fails, Alan Mackenzie, 2022/03/08
- bug#54079: 29.0.50; Method dispatching eratically fails,
Stefan Monnier <=
- bug#54079: 29.0.50; Method dispatching eratically fails, Alan Mackenzie, 2022/03/09
- bug#54079: 29.0.50; Method dispatching eratically fails, Stefan Monnier, 2022/03/09
- bug#54079: 29.0.50; Method dispatching eratically fails, Alan Mackenzie, 2022/03/09
- bug#54079: 29.0.50; Method dispatching eratically fails, Stefan Monnier, 2022/03/09
- bug#54079: 29.0.50; Method dispatching eratically fails, Alan Mackenzie, 2022/03/11
- bug#54079: 29.0.50; Method dispatching eratically fails, Stefan Monnier, 2022/03/11
- bug#54079: 29.0.50; Method dispatching eratically fails, Alan Mackenzie, 2022/03/13
- bug#54079: 29.0.50; Method dispatching eratically fails, Stefan Monnier, 2022/03/14
- bug#54079: 29.0.50; Method dispatching eratically fails, Michael Heerdegen, 2022/03/08
- bug#54079: 29.0.50; Method dispatching eratically fails, Alan Mackenzie, 2022/03/09