bug#60805: [PATCH] Extend go-ts-mode with command to add docstring to function

[Evgeni Kolev <evgenysw@gmail.com>]

> In that case, maybe it is even simpler to do something like:
>
> (defun defun-comment-p ()
>   (interactive)
>   (save-restriction
>     (narrow-to-defun t)
>     (goto-char (point-min))
>     (equal
>       (treesit-node-type (treesit-node-at (point)))
>       "comment")))

BTW I've noticed M-x mark-defun doesn't work correctly in some cases
with go-ts-mode (other *-gs-modes might also be affected, I haven't
tested). I wonder if narrow-to-defun could also be affected. For
example, with this Go code:

```
package main

func main() {

}

// some docstring
func main1() {

}
```
With the point in the body of "main1()", running M-x mark-defun marks
the blank line between the two functions instead of main1(). I'll
report this as a separate bug.

> However, now this code would act on code such as:
>
> ```
> //go:generate protoc .........
>
> // some docstring
> func main() {
>
> }
> ```
>
> And return point on the line with go:generate.  Is that desired?

I'd prefer to _not_ add special handling for "//go:..." comments which
are somewhat rare and typically put on the very first line of the
file. For your particular example the point should be put on "// some
docstring" because there's a separating blank line. This is not the
behavior with my patch - I'll try to improve it.


> Should we bind something to the C-c prefix?  I thought this was
> "user-reserved", so a user should bind them themselves.

I believe only "C-c letter" is user-reserved. I've drawn this
conclusion from here
https://www.gnu.org/software/emacs/manual/html_node/elisp/Key-Binding-Conventions.html