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bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginnin
From: |
Yang Yingchao |
Subject: |
bug#65885: Acknowledgement (29.1.50; wrong behaviour of treesit-beginning-of-defun in c++-ts-mode) |
Date: |
Thu, 14 Sep 2023 08:17:56 +0800 |
User-agent: |
mu4e 1.10.6; emacs 29.1.50 |
>> 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.
|
`----