rainbow-delimiters-mode, syntax-begin-function and font-lock-beginning-of-syntax-function

[fatiparty--- via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

Jan 26, 2022, 01:55 by monnier@iro.umontreal.ca:

>> Right, if the version of emacs has `syntax-begin-function', then one could use that,
>> as has been done.  I am making a new version without calls to things that would,
>>  be obsolete, but without breaking the colouring functionality. 
>>
>> There is a call to flush the cache `(syntax-ppss-flush-cache 0' with 
>> `(boundp 'syntax-begin-function)'.  Would this still be necessary? 
>>
>
> I recommend you read a bit more to understand a bit what these things do
> (e.g. what does it mean for `syntax-begin-function` to be nil) because
> changing code which you don't understand at all is just not fun.
>
>  Stefan
>

If I completely remove the section (in Emacs 27.2):

(when (or (bound-and-true-p syntax-begin-function)
          (bound-and-true-p font-lock-beginning-of-syntax-function))

  (syntax-ppss-flush-cache 0))

(when (boundp 'syntax-begin-function)
  (set (make-local-variable 'syntax-begin-function) nil))

(when (boundp 'font-lock-beginning-of-syntax-function)
  (set (make-local-variable 'font-lock-beginning-of-syntax-function) nil))


I don't see any obvious  adverse effects.


What was syntax-begin-function obsoleted in favour of?