bug#70074: 29.1; js-ts-mode doesn't define comment-line-break-function

[Dmitry Gutov <dmitry@gutov.dev>]

On 04/04/2024 15:32, Eli Zaretskii wrote:
>> From: Evan Davis<davis.evan.m@gmail.com>
>> Date: Fri, 29 Mar 2024 11:03:10 -0400
>>
>> js-ts-mode and js-mode behave differently when calling default-indent-new-line (M-j) within a multiline
>> comment.
>>
>> Observed behavior:
>>    - in js-mode, M-j calls c-indent-new-comment-line, which correctly inserts a newline, indented to the correct
>> column and prefixed with '*'
>>    - in js-ts-mode, M-j calls comment-indent-new-line, which inserts an indented newline without the prefix.
>>
>> Expected behavior:
>> Block comments should be handled the same in both modes.
>>
>> Steps to reproduce:
>> 1. emacs -Q
>> 2. open a scratch buffer in js-ts-mode and enter text (without quotes) "/*"
>> 3. press M-j
>> 4. observe newline is created without star prefix
>>
>> Follow the same steps in js-mode to observe the desired behavior.
> Dmitry, Yuan: any comments or suggestions?

I suppose following in js-mode's footsteps and reusing this part of CC 
Mode is the obvious solution.

I haven't looked at the implementation closely enough to suggest 
something else, but it'd of course be nice to be able to provide a 
self-contained, shorter re-implementation instead.