bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

[Philipp]

Insert the following form into *scratch*:

(defun f (a) (when-let (b (not a)) b))

Edebug-evaluate it using C-u M-C-x.

Now evaluate (f 1).  Edebug will not stop at the (not a) form, only the
`a' symbol.  The instrumented form is indeed incorrect:
(symbol-function 'f) gives

(closure
 (t)
 (a)
 (edebug-enter 'f
	       (list a)
	       #'(lambda nil
		   (edebug-after
		    (edebug-before 0)
		    3
		    (let*
			((b
			  (and t
			       (not
				(edebug-after 0 1 a)))))
		      (if b
			  (edebug-after 0 2 b)
			nil))))))

Note the missing edebug-before/after around the `not' form.

This can be rectified by swapping the two `&or' branches in the Edebug
specification for `if-let', which makes sense given the first branch is
often a superset of the second.  I don't mind doing that, but maybe
there are negative conseqences from that that I don't see?


In GNU Emacs 28.0.50 (build 120, aarch64-apple-darwin20.4.0, NS appkit-2022.44 Version 11.3.1 (Build 20E241))
 of 2021-05-17
Repository revision: f572735c5105a84da3175ae6cdad807fa103dfe1
Repository branch: master
Windowing system distributor 'Apple', version 10.3.2022
System Description:  macOS 11.3.1

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bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

[Philipp Stephani]

Am Di., 18. Mai 2021 um 00:09 Uhr schrieb Philipp <p.stephani2@gmail.com>:
> This can be rectified by swapping the two `&or' branches in the Edebug
> specification for `if-let', which makes sense given the first branch is
> often a superset of the second.  I don't mind doing that, but maybe
> there are negative conseqences from that that I don't see?

I guess the easiest way to find out is to make the change and see
whether anything breaks ;-)
Done with commit 9676d41b8301b84e07717e633059a3f2b5c4c9d8.

bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

[Glenn Morris]

Philipp wrote:

> This can be rectified by swapping the two `&or' branches in the Edebug
> specification for `if-let', which makes sense given the first branch is
> often a superset of the second.  I don't mind doing that, but maybe
> there are negative conseqences from that that I don't see?

Since 9676d41, edebug-tests-duplicate-symbol-backtrack fails.
Ref eg https://hydra.nixos.org/build/143298928
Reproduced on CentOS 8.3.

bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

[Philipp Stephani]

Am Di., 18. Mai 2021 um 16:59 Uhr schrieb Glenn Morris <rgm@gnu.org>:
>
> Philipp wrote:
>
> > This can be rectified by swapping the two `&or' branches in the Edebug
> > specification for `if-let', which makes sense given the first branch is
> > often a superset of the second.  I don't mind doing that, but maybe
> > there are negative conseqences from that that I don't see?
>
> Since 9676d41, edebug-tests-duplicate-symbol-backtrack fails.
> Ref eg https://hydra.nixos.org/build/143298928
> Reproduced on CentOS 8.3.

Hmm, I can't reproduce this on Debian. But I don't see how this could
be OS-dependent.

bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

[Lars Ingebrigtsen]

Philipp Stephani <p.stephani2@gmail.com> writes:

> Hmm, I can't reproduce this on Debian. But I don't see how this could
> be OS-dependent.

It reproduces fine here on Debian/bullseye, at least:

1 unexpected results:
   FAILED  edebug-tests-duplicate-symbol-backtrack



-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

[Philipp Stephani]

Am Di., 18. Mai 2021 um 18:25 Uhr schrieb Lars Ingebrigtsen <larsi@gnus.org>:
>
> Philipp Stephani <p.stephani2@gmail.com> writes:
>
> > Hmm, I can't reproduce this on Debian. But I don't see how this could
> > be OS-dependent.
>
> It reproduces fine here on Debian/bullseye, at least:
>
> 1 unexpected results:
>    FAILED  edebug-tests-duplicate-symbol-backtrack
>

Yeah, I can also reproduce it now. Not sure what changed in the
meantime on my system.

bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

[Philipp Stephani]

Am Di., 18. Mai 2021 um 18:27 Uhr schrieb Philipp Stephani
<p.stephani2@gmail.com>:
>
> Am Di., 18. Mai 2021 um 18:25 Uhr schrieb Lars Ingebrigtsen <larsi@gnus.org>:
> >
> > Philipp Stephani <p.stephani2@gmail.com> writes:
> >
> > > Hmm, I can't reproduce this on Debian. But I don't see how this could
> > > be OS-dependent.
> >
> > It reproduces fine here on Debian/bullseye, at least:
> >
> > 1 unexpected results:
> >    FAILED  edebug-tests-duplicate-symbol-backtrack
> >
>
> Yeah, I can also reproduce it now. Not sure what changed in the
> meantime on my system.

Ah. See the FIXME in the test:

                     ;; FIXME: There are twice as many inner
                     ;; definitions as expected due to Bug#42701.
                     ;; Once that bug is fixed, remove the duplicates.

Bug#42701 still isn't fixed, but the fix to bug#48489 has "suppressed"
its symptom in this case. We can therefore resolve this FIXME.
However, then the edebug-tests-duplicate-symbol-backtrack doesn't
really test any more what it should be testing. So I'll see that I can
change it to restore the previous behavior (which requires
backtracking and overlapping &or branches).

bug#48489: 28.0.50; Incorrect Edebug instrumentation for old `when-let' form

[Philipp Stephani]

Am Di., 18. Mai 2021 um 18:34 Uhr schrieb Philipp Stephani
<p.stephani2@gmail.com>:
>
> Am Di., 18. Mai 2021 um 18:27 Uhr schrieb Philipp Stephani
> <p.stephani2@gmail.com>:
> >
> > Am Di., 18. Mai 2021 um 18:25 Uhr schrieb Lars Ingebrigtsen <larsi@gnus.org>:
> > >
> > > Philipp Stephani <p.stephani2@gmail.com> writes:
> > >
> > > > Hmm, I can't reproduce this on Debian. But I don't see how this could
> > > > be OS-dependent.
> > >
> > > It reproduces fine here on Debian/bullseye, at least:
> > >
> > > 1 unexpected results:
> > >    FAILED  edebug-tests-duplicate-symbol-backtrack
> > >
> >
> > Yeah, I can also reproduce it now. Not sure what changed in the
> > meantime on my system.
>
> Ah. See the FIXME in the test:
>
>                      ;; FIXME: There are twice as many inner
>                      ;; definitions as expected due to Bug#42701.
>                      ;; Once that bug is fixed, remove the duplicates.
>
> Bug#42701 still isn't fixed, but the fix to bug#48489 has "suppressed"
> its symptom in this case. We can therefore resolve this FIXME.
> However, then the edebug-tests-duplicate-symbol-backtrack doesn't
> really test any more what it should be testing. So I'll see that I can
> change it to restore the previous behavior (which requires
> backtracking and overlapping &or branches).

Done with commit 63e4ed1c8f1c5bbf59c366134d379bae972201f9.