Package: emacs;
Reported by: Stephen Berman <stephen.berman <at> gmx.net>
Date: Fri, 22 Mar 2024 15:01:01 UTC
Severity: normal
Found in version 30.0.50
Done: Eli Zaretskii <eliz <at> gnu.org>
Bug is archived. No further changes may be made.
Message #23 received at 69941 <at> debbugs.gnu.org (full text, mbox):
From: Mauro Aranda <maurooaranda <at> gmail.com> To: Stephen Berman <stephen.berman <at> gmx.net> Cc: Eli Zaretskii <eliz <at> gnu.org>, 69941 <at> debbugs.gnu.org, Stefan Monnier <monnier <at> iro.umontreal.ca> Subject: Re: bug#69941: 30.0.50; Faulty fontification of radio button widgets Date: Thu, 18 Apr 2024 07:18:29 -0300
> On Sun, 24 Mar 2024 19:45:20 +0100 Stephen Berman <stephen.berman <at> gmx.net> wrote: > >> On Sat, 23 Mar 2024 17:49:53 -0300 Mauro Aranda <maurooaranda <at> gmail.com> wrote: >> >>> Stephen Berman <stephen.berman <at> gmx.net> writes: >>> >>>> 5. Tab back to "Activate" and press RET, again restoring the initial >>>> state. Now tab to radio button "Two" and press RET. >>>> => The fontification is the same as in step 4: radio button "Two" has >>>> the widget-inactive face but radio button "One" has the default (active) >>>> face, though it is again inactive. Repeatedly pressing either of the >>>> radio buttons (after activating them), does not change the fontification >>>> of "One" again. >>>> >>>> >>>> The faulty fontification of radio button "One" also obtains if there is >>>> just one radio button instead of two, and if there are more than two >>>> radio buttons, it is only the first one that displays the odd >>>> fontification (admittedly, I've only test up to three radio buttons). >>>> >>>> I've tried to debug this and found that the problem seems to be due to >>>> the sexp (set-marker-insertion-type from t) near the end of >>>> widget-default-create, which advances the marker specified by the >>>> widget's :from property. Changing t to nil fixes the faulty >>>> fontification of the first radio button. >>>> >>>> I investigated the history of this code, and while the value t for the >>>> marker insertion type was used in the initial commit, it was changed to >>>> nil in commit e0f956935, with the message "Insert new text at the :from >>>> marker _after_ the marker, not before it." But 18 days later it was >>>> changed back to t in commit 3bff434b8, that also added "Document need to >>>> put some text before the %v escape in :format string" of editable-field >>>> widgets. (I looked at the bug-gnu-emacs and emacs-devel mailing list >>>> archives but found nothing relevant at the time just prior to these >>>> commits.) >>> >>> I'm pretty sure it makes sense for user-editable widgets that the >>> value for insertion-type be t. >> >> Yes, if my understanding is correct, it's just radio-button-choice >> widgets that need (the effect of) insertion type nil (at least for >> setting the widget-inactive face), see below. >> >>>> So evidently the advancing marker insertion type is needed for at least >>>> some widgets, though it seems to be problematic for radio buttons. So I >>>> tried to conditionalize the choice of t or nil on the type of the >>>> widget. I used (not (eq 'radio-button (widget-type widget))), since the >>>> argument `widget' of widget-default-create is, according to Edebug, >>>> indeed radio-button, so negating the eq sexp returns nil, which I had >>>> found to be the value of the marker insertion type that fixes the >>>> fontification (however, I couldn't think of a way of limiting the >>>> conditioning to only the first radio button, but in my testing so far >>>> that lack doesn't appear to make a difference). >>> >>> I'm not sure if the right target is the radio-button widget. It could >>> be the radio-button-choice widget. Did you try to conditionalize the code >>> against the radio-button-choice widget? >> >> I didn't, because I got hung up on the radio-button widget, since in >> Edebug that is what I saw and (mistakenly) took to be the current widget >> when widget-inactive face is set. But the resulting marker insertion >> type discrepancy is really proof that I was looking at the wrong widget >> type (as I already realized in my comments cited below, but I didn't >> think to simply try it with radio-button-choice until now, so thanks for >> pointing me in the right direction!). And indeed, with >> radio-button-choice, negating the eq test DTRT, i.e., using (not (eq >> 'radio-button-choice (widget-type widget))) as the condtion results in >> the correct fontification. Since this sexp gives the >> radio-button-choice widget's :from property the marker insertion type >> nil, there is no discrepancy between using that sexp and directly using >> nil, so changing my patch to use that condition would be in improvement. >> Alternatively, ... >> >>>> But in fact, using the negation of the value of the eq sexp results in >>>> the same faulty fontification, while omitting the negation (as in the >>>> attached patch), which yields the advancing insertion type t, gives the >>>> correct fontification, just like using nil does. This makes no sense to >>>> me, yet it is reliably reproducible. The only possible explanation that >>>> occurs to me is that the bug is triggered elsewhere in the Emacs code >>>> and somehow using the sexp that evaluates to t as the marker insertion >>>> type affects that code, while using t itself does not (or rather, has >>>> the opposite effect); but how that could be and where the culpable code >>>> is, I don't know (as a guess, perhaps in the C code that adds faces, but >>>> I don't know how to debug that). If anyone knows or has an idea what's >>>> going on here, please communicate it. In the meantime I will continue >>>> to use the widget library with the patch to see whether it has unwanted >>>> consequences. >>> >>> I don't know much about that code in Emacs. If we find some hack that >>> works maybe we can use that until someone figures it out. But again, >>> given your analysis, I'd like to find out if using the condition on the >>> radio-button-choice widget works as expected. And of course, the hack >>> shouldn't be added to the widget-default-create, which should remain >>> type agnostic. >> >> ... since the issue is fontification with the widget-inactive face, >> perhaps a better location for the condition is widget-specify-inactive, >> as in the attached patch. It's still a hack though, since >> widget-specify-inactive is also type-agnostic by design. But if the >> issue really is confined to radio-button-choice widget's, I guess any >> solution will have to refer to that type. However, between adding the >> condition to widget-specify-inactive or to widget-default-create, I'm >> not sure which is less hacky: since the patch to widget-default-create >> effectively undoes the result of setting the marker insertion type to t, >> perhaps it is cleaner just to set it to nil for radio-button-choice >> widgets in widget-default-create. Or maybe someone will come up with a >> better fix... >> >> Steve Berman >> >> diff --git a/lisp/wid-edit.el b/lisp/wid-edit.el >> index 172da3db1e0..01319853edc 100644 >> --- a/lisp/wid-edit.el >> +++ b/lisp/wid-edit.el >> @@ -532,6 +532,17 @@ widget-inactive >> >> (defun widget-specify-inactive (widget from to) >> "Make WIDGET inactive for user modifications." >> + ;; When WIDGET is a radio-button-choice widget and its first child >> + ;; radio-button widget is inserted, the marker FROM, which has >> + ;; insertion type t, advances to the position after the radio button, >> + ;; and since the overlay setting the widget-inactive face begins at >> + ;; the position of FROM, this results in the first radio button >> + ;; incorrectly not being fontified with the widget-inactive face. To >> + ;; ensure it is correctly fontified, we move FROM backward by 3, >> + ;; i.e. the length of the radio-button widget (from its string >> + ;; representation "( )" or "(x)") (bug#69941). >> + (when (eq (widget-type widget) 'radio-button-choice) >> + (set-marker from (- from 3))) >> (unless (widget-get widget :inactive) >> (let ((overlay (make-overlay from to nil t nil))) >> (overlay-put overlay 'face 'widget-inactive) > > To fix this bug, do you have a preference between this patch for > widget-specify-inactive and the attached patch for > widget-default-create? Or do you have a better fix? > > Steve Berman I don't really have a better fix. I mean, ideally, we'd find the reason why the setting behaves differently for the radio-button-choice widget, and only for the first one in a radio widget, as it seems to me. But I'll need more time to be able to look into that. That said, if Eli is OK with installing a minor hack (with a FIXME, please), I don't have problems. And since it's a hack (and hopefully temporary), it's better if we keep it at widget-default-create then.
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