bug#67357: [PATCH] Fix c-ts-mode block indent when first-siblings are comments

[Noah Peart]

I did notice an issue with testing solutions in `c-ts-mode-resources/indent.erts`.

In cases where no indentation is applied (eg. comment is first-sibling) or there

is no matching rule (eg. else_clause), the test case can still pass since 

the test cases are written with the proper indentation already.  So, despite

no indentation being applied, the result still matches the expected result.

On Fri, Nov 24, 2023 at 6:35 AM Noah Peart <noah.v.peart@gmail.com> wrote:

> I'm sorry I insist on a complete recipe with all the details

Ok, lemme try again :)

To reproduce the indentation bugs for unbracketed `else_clause`, and 

do-while:

1. open a buffer and insert the following:

    int main() {
      if (true)
        puts("Hello");
      else
                    puts("No matched rule!"); // 1
      do
        puts("Hello");
                    while (indented_as_part_of_block);  // 2
    }

2. call `M-x example-setup` to configure `c-ts-mode`

3. `M-x indent-region` to indent the whole buffer

You should see that the line with comment `1` has not been

indented, and the line with comment `2` has been indented to the 

same level as the previous line.

To reproduce the indentation bugs when comments are the first

siblings:

1. open a buffer and insert:

    int main() {
      while (true) { /* foo */
                          if (true) { // 1
                          puts ("Hello"); // 2
       }
      }
    }

2. call `M-x example-setup` to configure `c-ts-mode`

3. `M-x indent-region` to indent the whole buffer

You should see that the lines with comments `1` and `2` have

not been indented at all.

On Fri, Nov 24, 2023 at 6:07 AM Eli Zaretskii <eliz@gnu.org> wrote:

> From: Noah Peart <noah.v.peart@gmail.com>
> Date: Fri, 24 Nov 2023 05:47:34 -0800
> Cc: Eli Zaretskii <eliz@gnu.org>, casouri@gmail.com, 67357@debbugs.gnu.org
>
> Sorry for the confusion: to setup the `c-ts-mode` buffers to reproduce bugs,
> run the following to configure `c-ts-mode` with `linux` style:
>
>     (defun example-setup ()
>       (interactive)
>       (c-ts-mode)
>       (setq-local indent-tabs-mode nil)
>       (setq-local c-ts-mode-indent-offset 2)
>       (c-ts-mode-set-style 'linux))

Thanks, but what to do after (or before?) the above, to actually
reproduce the problem?

I'm sorry I insist on a complete recipe with all the details, but IME
without having such a recipe, it is all too easy to create
misunderstandings about the problem, and harder to test solutions.