GNU bug report logs - #65631
Xref updates stack in case of error

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: bug-gnu-emacs <at> gnu.org
Subject: Xref updates stack in case of error
Date: Wed, 30 Aug 2023 19:44:13 +0300

X-Debbugs-CC: Dmitry Gutov <dmitry <at> gutov.dev>

0. emacs -Q
1. move point to any word
2. type 'M-.' (xref-find-definitions)
3. an error is displayed correctly "No definitions found for: This"

But the problem is that an unrecognized word is added to the xref stack.
So the context menu shows "Go Back", and 'M-,' (xref-go-back) goes back
to that word.

Message #8 received at 65631 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Juri Linkov <juri <at> linkov.net>
Cc: 65631 <at> debbugs.gnu.org, dmitry <at> gutov.dev
Subject: Re: bug#65631: Xref updates stack in case of error
Date: Wed, 30 Aug 2023 20:01:02 +0300

> Cc: dmitry gutov <dmitry <at> gutov.dev>
> From: Juri Linkov <juri <at> linkov.net>
> Date: Wed, 30 Aug 2023 19:44:13 +0300
> 
> X-Debbugs-CC: Dmitry Gutov <dmitry <at> gutov.dev>
> 
> 0. emacs -Q
> 1. move point to any word
> 2. type 'M-.' (xref-find-definitions)
> 3. an error is displayed correctly "No definitions found for: This"
> 
> But the problem is that an unrecognized word is added to the xref stack.
> So the context menu shows "Go Back", and 'M-,' (xref-go-back) goes back
> to that word.

FWIW, I'm not sure this is necessarily a bug.  It looks like a bug in
your case, because you deliberately tricked Xref into using a word
that is definitely not a program symbol.  But that is not the case in
a more reasonable situation, where point is on a symbol, but for some
reason the symbol's definition is not found, e.g., because the TAGS
table needs to be regenerated.

Message #11 received at 65631 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 65631 <at> debbugs.gnu.org, dmitry <at> gutov.dev
Subject: Re: bug#65631: Xref updates stack in case of error
Date: Wed, 30 Aug 2023 20:16:07 +0300

>> 1. move point to any word
>> 2. type 'M-.' (xref-find-definitions)
>> 3. an error is displayed correctly "No definitions found for: This"
>>
>> But the problem is that an unrecognized word is added to the xref stack.
>> So the context menu shows "Go Back", and 'M-,' (xref-go-back) goes back
>> to that word.
>
> FWIW, I'm not sure this is necessarily a bug.  It looks like a bug in
> your case, because you deliberately tricked Xref into using a word
> that is definitely not a program symbol.  But that is not the case in
> a more reasonable situation, where point is on a symbol, but for some
> reason the symbol's definition is not found, e.g., because the TAGS
> table needs to be regenerated.

In case of error, point doesn't move.  So there is no need to go back.

Message #14 received at 65631 <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dmitry <at> gutov.dev>
To: Juri Linkov <juri <at> linkov.net>, Eli Zaretskii <eliz <at> gnu.org>
Cc: 65631 <at> debbugs.gnu.org
Subject: Re: bug#65631: Xref updates stack in case of error
Date: Thu, 31 Aug 2023 03:50:53 +0300

[Message part 1 (text/plain, inline)]

Hi!

On 30/08/2023 20:16, Juri Linkov wrote:
>>> 1. move point to any word
>>> 2. type 'M-.' (xref-find-definitions)
>>> 3. an error is displayed correctly "No definitions found for: This"
>>>
>>> But the problem is that an unrecognized word is added to the xref stack.
>>> So the context menu shows "Go Back", and 'M-,' (xref-go-back) goes back
>>> to that word.
>> FWIW, I'm not sure this is necessarily a bug.  It looks like a bug in
>> your case, because you deliberately tricked Xref into using a word
>> that is definitely not a program symbol.  But that is not the case in
>> a more reasonable situation, where point is on a symbol, but for some
>> reason the symbol's definition is not found, e.g., because the TAGS
>> table needs to be regenerated.
> In case of error, point doesn't move.  So there is no need to go back.

At this point, I was kind of feeling that this is a known-but-tolerated 
behavior (that some might already be relying on, also known as "spacebar 
heater" effect), but if it's still annoying, let's see about a fix.

How's the attached patch?

[xref--push-markers.diff (text/x-patch, attachment)]

Message #19 received at 65631 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Dmitry Gutov <dmitry <at> gutov.dev>
Cc: 65631 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>
Subject: Re: bug#65631: Xref updates stack in case of error
Date: Thu, 31 Aug 2023 19:33:07 +0300

>>>> 1. move point to any word
>>>> 2. type 'M-.' (xref-find-definitions)
>>>> 3. an error is displayed correctly "No definitions found for: This"
>>>>
>>>> But the problem is that an unrecognized word is added to the xref stack.
>>>> So the context menu shows "Go Back", and 'M-,' (xref-go-back) goes back
>>>> to that word.
>>> FWIW, I'm not sure this is necessarily a bug.  It looks like a bug in
>>> your case, because you deliberately tricked Xref into using a word
>>> that is definitely not a program symbol.  But that is not the case in
>>> a more reasonable situation, where point is on a symbol, but for some
>>> reason the symbol's definition is not found, e.g., because the TAGS
>>> table needs to be regenerated.
>> In case of error, point doesn't move.  So there is no need to go back.
>
> At this point, I was kind of feeling that this is a known-but-tolerated
> behavior (that some might already be relying on, also known as "spacebar
> heater" effect), but if it's still annoying, let's see about a fix.

It's not annoying, just surprises with the requirement to type extra ‘M-,’.

> How's the attached patch?

Thanks.  I expected a smaller change, but if this is still reliable,
then why not.  At least, it works in cases that I tested.

Message #24 received at 65631-done <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dmitry <at> gutov.dev>
To: Juri Linkov <juri <at> linkov.net>
Cc: 65631-done <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>
Subject: Re: bug#65631: Xref updates stack in case of error
Date: Fri, 1 Sep 2023 04:39:34 +0300

Version: 30.1

On 31/08/2023 19:33, Juri Linkov wrote:
>>>>> 1. move point to any word
>>>>> 2. type 'M-.' (xref-find-definitions)
>>>>> 3. an error is displayed correctly "No definitions found for: This"
>>>>>
>>>>> But the problem is that an unrecognized word is added to the xref stack.
>>>>> So the context menu shows "Go Back", and 'M-,' (xref-go-back) goes back
>>>>> to that word.
>>>> FWIW, I'm not sure this is necessarily a bug.  It looks like a bug in
>>>> your case, because you deliberately tricked Xref into using a word
>>>> that is definitely not a program symbol.  But that is not the case in
>>>> a more reasonable situation, where point is on a symbol, but for some
>>>> reason the symbol's definition is not found, e.g., because the TAGS
>>>> table needs to be regenerated.
>>> In case of error, point doesn't move.  So there is no need to go back.
>>
>> At this point, I was kind of feeling that this is a known-but-tolerated
>> behavior (that some might already be relying on, also known as "spacebar
>> heater" effect), but if it's still annoying, let's see about a fix.
> 
> It's not annoying, just surprises with the requirement to type extra ‘M-,’.
> 
>> How's the attached patch?
> 
> Thanks.  I expected a smaller change, but if this is still reliable,
> then why not.  At least, it works in cases that I tested.

I was looking for a smaller change, too. Thanks for testing.

Pushed to master in 17188e07ab9, closing.

Message #27 received at 65631 <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattias.engdegard <at> gmail.com>
To: Dmitry Gutov <dgutov <at> yandex.ru>
Cc: 65631 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>,
 Juri Linkov <juri <at> linkov.net>
Subject: bug#65631: Xref updates stack in case of error
Date: Fri, 1 Sep 2023 15:25:30 +0200

17188e07ab9 appears to break etags-tests on master.

Message #30 received at 65631 <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: Mattias Engdegård <mattias.engdegard <at> gmail.com>
Cc: 65631 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>,
 Juri Linkov <juri <at> linkov.net>
Subject: Re: bug#65631: Xref updates stack in case of error
Date: Sat, 2 Sep 2023 05:00:27 +0300

On 01/09/2023 16:25, Mattias Engdegård wrote:
> 17188e07ab9 appears to break etags-tests on master.

Thanks for reporting, should be fixed in f735eb9628.

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