From: Paul Eggert <eggert@cs.ucla.edu>
To: Alan Mackenzie <acm@muc.de>
Cc: michael_heerdegen@web.de, eliz@gnu.org, cpitclaudel@gmail.com,
monnier@IRO.UMontreal.CA, emacs-devel@gnu.org
Subject: Re: scratch/accurate-warning-pos: Solid progress: the branch now bootstraps.
Date: Mon, 26 Nov 2018 10:27:48 -0800 [thread overview]
Message-ID: <ed9fa4db-e88b-adbd-7091-2b4868127984@cs.ucla.edu> (raw)
In-Reply-To: <20181126094800.GA4030@ACM>
On 11/26/18 1:48 AM, Alan Mackenzie wrote:
>
>> The byte-compiler
>> interpreter would operate more slowly than the normal interpreter, but
>> that's OK. The main and the byte-compiler interpreter could mostly be
>> written with shared code, without slowing down the main interpreter.
>> Admittedly this would not be a project for the fainthearted.
> Indeed not. Where and how would this help with getting accurate source
> code positions?
From the point of view of the byte-compiler, it should help just as
well as scratch/accurate-warning-pos does, because it's just another way
to get the same information. Admittedly it's more work to implement this.
>> any method of outputting source-code locations will founder in the
>> presence of macros.
> scratch/accurate-warning-pos seems to do rather well in this regard.
No doubt it does better than master does. However, macros inevitably
cause problems when diagnosing problems. If there's a bug in a macro, it
could well be that the byte compiler will report the line number of the
call to the macro rather than of the macro itself (where the real bug
is). So any definition of a "solid" solution must provide some leeway
for the compiler to issue a "wrong" diagnostic when macros are involved.
Otherwise, if the goal is to provide a "solid" solution then the
goalposts will keep moving and there's no way that I could suggest a
solution that is unambiguously "solid".
>> Instead, attach positions to input objects that are guaranteed to be
>> unique so that retrieval is trivial.
> I think you mean conses here. I've tried this approach, spending a lot
> of time on it but not getting very far. The problem is, Lisp objects
> flow through lots of different conses as they are transformed by the
> compiler. Have a look at cconv-convert, which processes every function.
I took a brief look there and see a lot of calls to mapcar, which of
course would lose track of locations. But this should be fixable by
defining and using a new function mapcar-pos, which acts like mapcar
except it also copies location information from the input list's conses
to the corresponding conses in the output list.
You're right that this would involve many changes to the byte compiler,
but the changes should be reasonably mechanical (e.g., change mapcar to
mapcar-pos) and the overall approach should be preferable to changing
how 'eq' works.
> The approach I tried
> before to implement this was to ensure that after any source
> transformation, the result was written back to the original cons using
> setcar and setcdr.
If location info is kept in a hash table that maps objects to locations,
then mapcar-pos can preserve location info merely by updating a hash
table. There should be no need for setcar and setcdr on the original cons.
next prev parent reply other threads:[~2018-11-26 18:27 UTC|newest]
Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-17 12:45 scratch/accurate-warning-pos: First tentative successes Alan Mackenzie
2018-11-17 13:13 ` Eli Zaretskii
2018-11-23 13:09 ` scratch/accurate-warning-pos: Solid progress: the branch now bootstraps Alan Mackenzie
2018-11-25 11:26 ` Charles A. Roelli
2018-11-25 14:31 ` Alan Mackenzie
2018-11-25 15:12 ` Andreas Schwab
2018-11-25 15:42 ` Alan Mackenzie
2018-11-25 16:40 ` Eli Zaretskii
2018-11-25 17:59 ` Alan Mackenzie
2018-11-25 18:15 ` Eli Zaretskii
2018-11-25 18:23 ` Alan Mackenzie
2018-11-25 19:36 ` Alan Mackenzie
2018-11-25 16:22 ` Stefan Monnier
2018-11-25 17:35 ` Alan Mackenzie
2018-11-25 18:22 ` Stefan Monnier
2018-11-25 19:54 ` Alan Mackenzie
2018-11-25 20:08 ` Stefan Monnier
2018-11-26 9:52 ` Alan Mackenzie
2018-11-26 10:16 ` Alan Mackenzie
2018-11-25 16:38 ` Eli Zaretskii
2018-11-25 17:27 ` Andreas Schwab
2018-11-25 17:31 ` Alan Mackenzie
2018-11-25 17:39 ` Eli Zaretskii
2018-11-25 18:08 ` Alan Mackenzie
2018-11-25 18:45 ` Paul Eggert
2018-11-25 19:30 ` Alan Mackenzie
2018-11-25 20:12 ` Paul Eggert
2018-11-25 21:29 ` Alan Mackenzie
2018-11-26 1:41 ` Paul Eggert
2018-11-26 3:41 ` Eli Zaretskii
2018-11-26 17:43 ` Paul Eggert
2018-11-26 18:43 ` Alan Mackenzie
2018-11-26 19:18 ` Clément Pit-Claudel
2018-11-26 19:42 ` Alan Mackenzie
2018-11-27 1:07 ` Gemini Lasswell
2018-11-27 1:45 ` Alan Mackenzie
2018-11-27 6:06 ` Eli Zaretskii
2018-11-27 2:48 ` Paul Eggert
2018-11-27 7:43 ` Alan Mackenzie
2018-11-27 20:27 ` Paul Eggert
2018-11-27 21:15 ` Alan Mackenzie
2018-11-27 21:37 ` Paul Eggert
2018-11-27 21:53 ` Alan Mackenzie
2018-11-28 1:11 ` Paul Eggert
2018-11-28 12:04 ` Alan Mackenzie
2018-11-29 21:28 ` Paul Eggert
2018-11-29 22:05 ` Alan Mackenzie
2018-11-30 17:50 ` Paul Eggert
2018-11-30 18:55 ` Alan Mackenzie
2018-11-30 20:14 ` Paul Eggert
2018-11-30 22:02 ` Alan Mackenzie
2018-11-30 23:46 ` Paul Eggert
2018-12-01 7:35 ` martin rudalics
2018-12-01 8:25 ` Eli Zaretskii
2018-12-01 11:08 ` Alan Mackenzie
2018-12-01 11:36 ` Eli Zaretskii
2018-12-01 12:47 ` Alan Mackenzie
2018-12-01 14:09 ` martin rudalics
2018-12-01 14:30 ` Stefan Monnier
2018-12-01 16:30 ` martin rudalics
2018-12-01 19:56 ` Stefan Monnier
2018-12-01 14:59 ` Eli Zaretskii
2018-12-01 16:31 ` martin rudalics
2018-12-01 16:53 ` Eli Zaretskii
2018-12-01 19:04 ` martin rudalics
2018-12-01 19:22 ` Eli Zaretskii
2018-12-01 17:21 ` Alan Mackenzie
2018-12-01 17:44 ` Michael Heerdegen
2018-12-01 18:58 ` Alan Mackenzie
2018-12-01 20:26 ` Alan Mackenzie
2018-12-01 17:48 ` Eli Zaretskii
2018-12-01 21:00 ` Paul Eggert
2018-12-01 17:50 ` Clément Pit-Claudel
2018-12-01 18:26 ` Yuri Khan
2018-12-01 19:15 ` Clément Pit-Claudel
2018-12-01 21:26 ` Paul Eggert
2018-12-02 6:48 ` Yuri Khan
2018-12-02 18:39 ` Gemini Lasswell
2018-12-03 2:28 ` Stefan Monnier
2018-12-01 19:04 ` martin rudalics
2018-12-02 22:53 ` Dmitry Gutov
2018-12-01 0:26 ` Gemini Lasswell
2018-12-01 11:48 ` Alan Mackenzie
2018-11-27 22:09 ` Stefan Monnier
2018-11-28 2:18 ` Paul Eggert
2018-11-28 2:43 ` Stefan Monnier
2018-11-28 5:13 ` Paul Eggert
2018-11-28 6:03 ` Gemini Lasswell
2018-11-28 5:39 ` Gemini Lasswell
2018-11-28 13:06 ` Stefan Monnier
2018-11-28 6:28 ` Eli Zaretskii
2018-11-28 22:50 ` Paul Eggert
2018-11-29 7:19 ` Eli Zaretskii
2018-11-29 10:54 ` Alan Mackenzie
2018-11-29 11:13 ` Eli Zaretskii
2018-11-29 11:37 ` Alan Mackenzie
2018-11-29 21:12 ` Paul Eggert
2018-11-29 21:28 ` Alan Mackenzie
2018-11-28 0:53 ` Gemini Lasswell
2018-11-26 20:04 ` Stefan Monnier
2018-11-27 2:51 ` Paul Eggert
2018-11-26 9:48 ` Alan Mackenzie
2018-11-26 18:27 ` Paul Eggert [this message]
2018-11-25 18:48 ` Gemini Lasswell
2018-11-25 20:02 ` Stefan Monnier
2018-11-26 12:39 ` Alan Mackenzie
2018-11-26 16:14 ` Gemini Lasswell
2018-11-26 17:06 ` Alan Mackenzie
2018-11-26 17:24 ` Alan Mackenzie
2018-11-29 12:26 ` scratch/accurate-warning-pos: Some real world timings Alan Mackenzie
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