bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginning-of-defun in c++-ts-mode)

bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginning-of-defun in c++-ts-mode)

[Yang Yingchao via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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It seams that there is an issue with the behavior of `treesit-beginning-of-defun` function in
`c++-ts-mode` when there are static variables present in the source code. For instance, in the
provided code snippet, if the cursor is initially placed on the line containing `int b`, and the
"C-M-a" is pressed, the cursor is positioned on line 4 instead of line 1 where the beginning of
the function is located.

,----
| void func		// c-ts-mode: treesit-beginning-of-defun stops in this line,   RIGHT
| {
|   char * msg;
|   static int a; // c++-ts-mode: treesit-beginning-of-defun stops in this line, WRONG
|   int b;        // PUT CUSOR HERE
| }
`----

it works in c-ts-mode works normally.

Regards.



On Tue, Sep 12 2023, help-debbugs@gnu.org (GNU bug Tracking System) wrote:

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Regards,

-- *Yang Yingchao*

bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginning-of-defun in c++-ts-mode)

[Eli Zaretskii]

> Date: Tue, 12 Sep 2023 12:41:32 +0800
> From:  Yang Yingchao via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> It seams that there is an issue with the behavior of `treesit-beginning-of-defun` function in
> `c++-ts-mode` when there are static variables present in the source code. For instance, in the
> provided code snippet, if the cursor is initially placed on the line containing `int b`, and the
> "C-M-a" is pressed, the cursor is positioned on line 4 instead of line 1 where the beginning of
> the function is located.
> 
> ,----
> | void func		// c-ts-mode: treesit-beginning-of-defun stops in this line,   RIGHT
> | {
> |   char * msg;
> |   static int a; // c++-ts-mode: treesit-beginning-of-defun stops in this line, WRONG
> |   int b;        // PUT CUSOR HERE
> | }
> `----
> 
> it works in c-ts-mode works normally.

If you want c++-ts-mode to work like c-ts-mode, set
treesit-defun-tactic to 'top-level'.  By default, we try to support
nested defuns in C++, but not in C.

bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginning-of-defun in c++-ts-mode)

[Yang Yingchao via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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>> Date: Tue, 12 Sep 2023 12:41:32 +0800
>> From:  Yang Yingchao via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>>
>> It seams that there is an issue with the behavior of `treesit-beginning-of-defun` function in
>> `c++-ts-mode` when there are static variables present in the source code. For instance, in the
>> provided code snippet, if the cursor is initially placed on the line containing `int b`, and the
>> "C-M-a" is pressed, the cursor is positioned on line 4 instead of line 1 where the beginning of
>> the function is located.
>>
>> ,----
>> | void func		// c-ts-mode: treesit-beginning-of-defun stops in this line,   RIGHT
>> | {
>> |   char * msg;
>> |   static int a; // c++-ts-mode: treesit-beginning-of-defun stops in this line, WRONG
>> |   int b;        // PUT CUSOR HERE
>> | }
>> `----
>>
>> it works in c-ts-mode works normally.
>
> If you want c++-ts-mode to work like c-ts-mode, set
> treesit-defun-tactic to 'top-level'.  By default, we try to support
> nested defuns in C++, but not in C.


I apologize, but I realized that I have already asked this question before.

However, setting 'treesit-defun-tactic' to 'top-level' could cause other
issues, as seen in the following snippets:


,----
| class Name {
| public:
|   Name()
|   {
|     // cursor here
|   }
| 
|   void func()
|   {
|     static int a;
|   }
| 
| };
`----

Suppose the cursor is in line 5, and "C-M-a" is pressed:

- In 'c++-mode', the cursor will be moved to the start of the function 'Name()', which is the expected behavior.
- In 'c++-ts-mode':
  - With 'treesit-defun-tactic' set to 'nested', it behaves the same as in 'c++-mode'.
  - With 'treesit-defun-tactic' set to 'top-level', the cursor is moved to the beginning of the class, i.e., line 1.

Is it possible to make 'c++-ts-mode' behave the same as in 'c++-mode'?

Regards.

bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginning-of-defun in c++-ts-mode)

[Yang Yingchao via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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>>> Date: Tue, 12 Sep 2023 12:41:32 +0800
>>> From:  Yang Yingchao via "Bug reports for GNU Emacs,
>>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>>>
>>> It seams that there is an issue with the behavior of `treesit-beginning-of-defun` function in
>>> `c++-ts-mode` when there are static variables present in the source code. For instance, in the
>>> provided code snippet, if the cursor is initially placed on the line containing `int b`, and the
>>> "C-M-a" is pressed, the cursor is positioned on line 4 instead of line 1 where the beginning of
>>> the function is located.
>>>
>>> ,----
>>> | void func		// c-ts-mode: treesit-beginning-of-defun stops in this line,   RIGHT
>>> | {
>>> |   char * msg;
>>> |   static int a; // c++-ts-mode: treesit-beginning-of-defun stops in this line, WRONG
>>> |   int b;        // PUT CUSOR HERE
>>> | }
>>> `----
>>>
>>> it works in c-ts-mode works normally.
>>
>> If you want c++-ts-mode to work like c-ts-mode, set
>> treesit-defun-tactic to 'top-level'.  By default, we try to support
>> nested defuns in C++, but not in C.
>
>
> I apologize, but I realized that I have already asked this question before.
>
> However, setting 'treesit-defun-tactic' to 'top-level' could cause other
> issues, as seen in the following snippets:
>
>
> ,----
> | class Name {
> | public:
> |   Name()
> |   {
> |     // cursor here
> |   }
> |
> |   void func()
> |   {
> |     static int a;
> |   }
> |
> | };
> `----
>
> Suppose the cursor is in line 5, and "C-M-a" is pressed:
>
> - In 'c++-mode', the cursor will be moved to the start of the function 'Name()', which is the expected behavior.
> - In 'c++-ts-mode':
>   - With 'treesit-defun-tactic' set to 'nested', it behaves the same as in 'c++-mode'.
>   - With 'treesit-defun-tactic' set to 'top-level', the cursor is moved to the beginning of the class, i.e., line 1.
>
> Is it possible to make 'c++-ts-mode' behave the same as in 'c++-mode'?
>
> Regards.

Maybe I'm wrong, but I would like to suggest reconsidering the solution to the 'begging-of-defun' issue related to the static *variable*. It feels strange to me to fix this issue by changing the 'treesit-defun-tactic', which is meant to apply to a *function* literally...

bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginning-of-defun in c++-ts-mode)

[Eli Zaretskii]

> From: Yang Yingchao <yang.yingchao@qq.com>
> Date: Wed, 13 Sep 2023 08:41:27 +0800
> 
> >>> Date: Tue, 12 Sep 2023 12:41:32 +0800
> >>> From:  Yang Yingchao via "Bug reports for GNU Emacs,
> >>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> >>>
> >>> It seams that there is an issue with the behavior of `treesit-beginning-of-defun` function in
> >>> `c++-ts-mode` when there are static variables present in the source code. For instance, in the
> >>> provided code snippet, if the cursor is initially placed on the line containing `int b`, and the
> >>> "C-M-a" is pressed, the cursor is positioned on line 4 instead of line 1 where the beginning of
> >>> the function is located.
> >>>
> >>> ,----
> >>> | void func		// c-ts-mode: treesit-beginning-of-defun stops in this line,   RIGHT
> >>> | {
> >>> |   char * msg;
> >>> |   static int a; // c++-ts-mode: treesit-beginning-of-defun stops in this line, WRONG
> >>> |   int b;        // PUT CUSOR HERE
> >>> | }
> >>> `----
> >>>
> >>> it works in c-ts-mode works normally.
> >>
> >> If you want c++-ts-mode to work like c-ts-mode, set
> >> treesit-defun-tactic to 'top-level'.  By default, we try to support
> >> nested defuns in C++, but not in C.
> >
> >
> > I apologize, but I realized that I have already asked this question before.
> >
> > However, setting 'treesit-defun-tactic' to 'top-level' could cause other
> > issues, as seen in the following snippets:
> >
> >
> > ,----
> > | class Name {
> > | public:
> > |   Name()
> > |   {
> > |     // cursor here
> > |   }
> > |
> > |   void func()
> > |   {
> > |     static int a;
> > |   }
> > |
> > | };
> > `----
> >
> > Suppose the cursor is in line 5, and "C-M-a" is pressed:
> >
> > - In 'c++-mode', the cursor will be moved to the start of the function 'Name()', which is the expected behavior.
> > - In 'c++-ts-mode':
> >   - With 'treesit-defun-tactic' set to 'nested', it behaves the same as in 'c++-mode'.
> >   - With 'treesit-defun-tactic' set to 'top-level', the cursor is moved to the beginning of the class, i.e., line 1.
> >
> > Is it possible to make 'c++-ts-mode' behave the same as in 'c++-mode'?
> >
> > Regards.
> 
> Maybe I'm wrong, but I would like to suggest reconsidering the solution to the 'begging-of-defun' issue related to the static *variable*. It feels strange to me to fix this issue by changing the 'treesit-defun-tactic', which is meant to apply to a *function* literally...

Yuan, any ideas or suggestions?

bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginning-of-defun in c++-ts-mode)

[Yang Yingchao via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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>> From: Yang Yingchao <yang.yingchao@qq.com>
>> Date: Wed, 13 Sep 2023 08:41:27 +0800
>>
>> >>> Date: Tue, 12 Sep 2023 12:41:32 +0800
>> >>> From:  Yang Yingchao via "Bug reports for GNU Emacs,
>> >>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>> >>>
>> >>> It seams that there is an issue with the behavior of `treesit-beginning-of-defun` function in
>> >>> `c++-ts-mode` when there are static variables present in the source code. For instance, in the
>> >>> provided code snippet, if the cursor is initially placed on the line containing `int b`, and the
>> >>> "C-M-a" is pressed, the cursor is positioned on line 4 instead of line 1 where the beginning of
>> >>> the function is located.
>> >>>
>> >>> ,----
>> >>> | void func		// c-ts-mode: treesit-beginning-of-defun stops in this line,   RIGHT
>> >>> | {
>> >>> |   char * msg;
>> >>> |   static int a; // c++-ts-mode: treesit-beginning-of-defun stops in this line, WRONG
>> >>> |   int b;        // PUT CUSOR HERE
>> >>> | }
>> >>> `----
>> >>>
>> >>> it works in c-ts-mode works normally.
>> >>
>> >> If you want c++-ts-mode to work like c-ts-mode, set
>> >> treesit-defun-tactic to 'top-level'.  By default, we try to support
>> >> nested defuns in C++, but not in C.
>> >
>> >
>> > I apologize, but I realized that I have already asked this question before.
>> >
>> > However, setting 'treesit-defun-tactic' to 'top-level' could cause other
>> > issues, as seen in the following snippets:
>> >
>> >
>> > ,----
>> > | class Name {
>> > | public:
>> > |   Name()
>> > |   {
>> > |     // cursor here
>> > |   }
>> > |
>> > |   void func()
>> > |   {
>> > |     static int a;
>> > |   }
>> > |
>> > | };
>> > `----
>> >
>> > Suppose the cursor is in line 5, and "C-M-a" is pressed:
>> >
>> > - In 'c++-mode', the cursor will be moved to the start of the function 'Name()', which is the expected behavior.
>> > - In 'c++-ts-mode':
>> >   - With 'treesit-defun-tactic' set to 'nested', it behaves the same as in 'c++-mode'.
>> >   - With 'treesit-defun-tactic' set to 'top-level', the cursor is moved to the beginning of
>> > the class, i.e., line 1.
>> >
>> > Is it possible to make 'c++-ts-mode' behave the same as in 'c++-mode'?
>> >
>> > Regards.
>>
>> Maybe I'm wrong, but I would like to suggest reconsidering the solution to the
>> 'begging-of-defun' issue related to the static *variable*. It feels strange to me to fix this
>> issue by changing the 'treesit-defun-tactic', which is meant to apply to a *function*
>> literally...
>
> Yuan, any ideas or suggestions?

Just FYI, I made some modifications to 'treesit--navigate-thing' in my own branch to fix this specific issue:

,----
| 1 file changed, 8 insertions(+)
| lisp/treesit.el | 8 ++++++++
| 
| modified   lisp/treesit.el
| @@ -2092,6 +2092,14 @@ treesit--navigate-thing
|          (pcase-let
|              ((`(,prev ,next ,parent)
|                (treesit--things-around pos regexp pred)))
| +
| +          ;; YYC: Special handling for static variable inside defun...
| +          (when (and (equal (treesit-node-type prev)
| +                            "storage_class_specifier")
| +                     (equal (treesit-node-type (treesit-node-parent prev))
| +                            "declaration"))
| +            (setq prev nil))
| +
|            ;; When PARENT is nil, nested and top-level are the same, if
|            ;; there is a PARENT, make PARENT to be the top-level parent
|            ;; and pretend there is no nested PREV and NEXT.
| 
`----