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bug#61208: 29.0.60; treesit-beginning/end-of-defun problem with macros i
From: |
Yuan Fu |
Subject: |
bug#61208: 29.0.60; treesit-beginning/end-of-defun problem with macros in c-ts-mode |
Date: |
Wed, 1 Feb 2023 18:32:26 -0800 |
> On Feb 1, 2023, at 4:49 AM, Eli Zaretskii <eliz@gnu.org> wrote:
>
>> Cc: yang.yingchao@qq.com
>> Date: Wed, 01 Feb 2023 14:33:24 +0800
>> From: Yang Yingchao via "Bug reports for GNU Emacs,
>> the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>>
>>
>> #define SWITCH()
>> #define CASE(name) case name:
>>
>> void func(int i) // LINE_E
>> {
>> SWITCH(i) // LINE_D
>> {
>> CASE(A) // LINE_C
>> {
>> ;
>> }
>> CASE(B) // LINE_B
>> {
>> ; // LINE_A
>> }
>> }
>> }
>>
>> When cursor is at LINE_A, and stoke `C-M-a`, cursor will go to LINE_B;
>> then `C-M-a` again, cursor goes to LINE_C, then `C-M-a` again, LINE_D,
>> and `C-M-a` again, finally to LINE_E...
>
> Set treesit-defun-tactic to 'top-level, and your problem is solved.
>
> Yuan, Theo: do we want to have that set by default in ts-c-mode? C
> doesn't have nested functions, so it should be a better default, what
> with all the cpp madness that the C grammar doesn't grok.
>
> Maybe also in C++ and Java -- AFAIU they don't have nested functions
> either.
Treesit-defun-tactic being ’nested isn’t the problem here, at least not the
direct cause of the problem. c-ts-mode doesn’t consider switch cases or if-else
statements as defuns. It only considers function, struct, enum, union, as
defun. So in a preprocessed C source file, C-M-a will move point to the
beginning of the function, line E. It does not in this particular file because
tree-sitter is thrown off by the SWITCH() and CASE() macro: it can’t tell what
they are and parses them as function definitions.
I don’t object setting treesit-defun-tactic to ’top-level in c-ts-mode, though.
It can hide problems like this. Just be aware that it merely hides the problem.
C++ and Java has classes, and when point is in a class, I think people expect
to move to the prev/next method rather than the beginning/end of the class. So
nested is still a better default IMO.
Yuan