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bug#65017: 29.1; Byte compiler interaction with cl-lib function objects,
From: |
Alan Mackenzie |
Subject: |
bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function |
Date: |
Thu, 10 Aug 2023 14:50:03 +0000 |
Hello, Stefan.
On Wed, Aug 09, 2023 at 23:41:56 -0400, Stefan Monnier wrote:
> >> > Are you sure?
> >> Yes.
> > What about two SWPs with the same symbol but different positions? If
> > they aren't considered EQ here, there will never be a match for the
> > first arm of the cond form in cl--labels-convert; then
> > cl--labels-convert-cache will get written, but never used.
> Nope: when it gets written, the `function` macro returns:
> (function <THESYMWITHPOS>)
> so the macro is immediately called again with the *exact* same
> <THESYMWITHPOS>, so the second time the `function` macro is called, the
> cache does hit (and it's the only case where it should hit), making the
> second call to the macro return the *exact* `eq`-same
> (function <THESYMWITHPOS>)
> list which is the trick that stops the infinite macroexpansion loop.
OK, thanks, I think I've got that now.
> Next time the `function` macro is invoked with a "similar" sympos the
> cache should *not* match because we don't want to accidentally replace
> (function <SOMESYMWITHPOS>)
> with
> (function <THESYMWITHPOS>)
> > And if, somehow, it does get used (the current code, I think), then (as
> > you write below) the argument F will get replaced by an F with the wrong
> > position. Am I right, here?
> That's right.
OK. So perhaps binding symbols-with-pos-enabled to nil around that eq
call could be the way to go.
> > Why must the F get replaced by a different F? There must surely be a
> > way, a simpler way than the current cl--labels-convert, to retain the
> > current F (hence, not corrupting its position)?
> There might. The current hack is the best I could come up with.
I'm not criticising the hack, not at all! But it could be better
commented, and the doc string for cl--labels-convert could be more
informative. The "why" is missing - why is necessary to handle
`function' as a macro? I think it's to inhibit the processing of
`function' as function somewhere else, but where and why? I think you
explained it, at least partly, in an earlier post on this thread.
> >> > If cl--labels-convert-cache is being used
> >> > inside the byte compiler, it surely needs to consider #<symbol foo at
> >> > 42> and #<symbol foo at 60> as eq?
> >> No, it should not treat them equal (when it does, it introduces an
> >> incorrect sympos and can thus lead to error messages pointing at the
> >> wrong place).
> > Then isn't what is wrong here the introduction of the incorrect SWP
> > rather than treating the two SWPs as EQ?
> I can't see how to separate one from the other here: the introduction of
> the incorrect SWP is due to treating the two SWP as `eq`.
> > This is obscure, difficult code. :-(
> Agreed.
> > We should think about committing a fix to the original bug,
> > sometime, too.
> I'm not completely sure we agree yet on what is "the original bug", but
> obviously I agree with your sentence :-)
I meant bug #65017. I committed a fix for it yesterday using the patch
I posted here on Sunday, and closed the bug.
> Stefan
--
Alan Mackenzie (Nuremberg, Germany).
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, (continued)
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Alan Mackenzie, 2023/08/04
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Eli Zaretskii, 2023/08/04
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Alan Mackenzie, 2023/08/04
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Eli Zaretskii, 2023/08/04
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Stefan Monnier, 2023/08/05
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Stefan Monnier, 2023/08/05
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Alan Mackenzie, 2023/08/06
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Stefan Monnier, 2023/08/07
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Alan Mackenzie, 2023/08/08
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Stefan Monnier, 2023/08/09
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function,
Alan Mackenzie <=
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Stefan Monnier, 2023/08/11
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Mattias EngdegÄrd, 2023/08/12
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Stefan Monnier, 2023/08/12
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Mattias EngdegÄrd, 2023/08/12
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Alan Mackenzie, 2023/08/12
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Stefan Monnier, 2023/08/12
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Alan Mackenzie, 2023/08/13
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Stefan Monnier, 2023/08/13
- bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Alan Mackenzie, 2023/08/14
bug#65017: 29.1; Byte compiler interaction with cl-lib function objects, removes symbol-function, Alan Mackenzie, 2023/08/03