bug#75226: [31.0.50] C++ ts-mode missing "alignof" as keyword

[Yuan Fu <casouri@gmail.com>]

> On Jan 3, 2025, at 11:34 PM, Yuan Fu <casouri@gmail.com> wrote:
> 
> 
> 
>> On Jan 3, 2025, at 3:38 AM, Eli Zaretskii <eliz@gnu.org> wrote:
>> 
>>> From: Yuan Fu <casouri@gmail.com>
>>> Date: Fri, 3 Jan 2025 00:50:46 -0800
>>> Cc: Jacob Faibussowitsch <jacob.fai@gmail.com>,
>>> 75226@debbugs.gnu.org
>>> 
>>>> On Jan 1, 2025, at 10:41 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>>>> 
>>>>> Eli, what’s the status of Emacs 30 right now? Can I push to emacs-30 and have this change queued for Emacs 30.2? Or should I wait a bit?
>>>> 
>>>> If this just adds a bunch of strings to c-ts-mode--keywords, it's okay
>>>> to add them on emacs-30.
>>> 
>>> Not quite, right now emacs-30’s c-ts-mode works with grammar as far back as v0.19.0 [1]. If we just add the keywords, c-ts-mode wouldn’t work with grammar v0.20.4 and earlier. So I’m going to add the new keywords with a check, which disables the new keywords if grammar doesn’t recognize them. Also there’re many missing keywords, none of which I have seen before :-), I need time to go over them and see how are they supposed by be fontified (keyword face or something else).
>>> 
>>> So let’s wait for 30.2.
>> 
>> If so, please install on master, and let's consider backporting it to
>> the emacs-30 branch after 30.1 is released.
>> 
>> Thanks.
> 
> Sounds good.
> 
> Yuan

I found that both c++-mode and c++-ts-mode fontifies C++ alternative operators like and_eq, xor, etc as keywords. Maybe we should fontify them in operator face (added in Emacs 29) instead?

Yuan