cc-mode: Make all parameters introduced in Emacs 26 optional

["Jostein Kjønigsen" <jostein@secure.kjonigsen.net>]

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Hey everyone.

While cc-mode seems to be a foundation for lots of the major-modes
shipped with Emacs, it's also used by third-party packages.
For major-modes shipped with Emacs, changes to the core cc-mode
functions is not that big of a problem, since they can be changed in
tandem with the changes to cc-mode itself.
For third party modules (like csharp-mode, which I maintain), changes to
cc-mode core-functions are more problematic due to Emacs lacking
reliable introspection capabilities.
As an example in the Emacs 26 branch c-font-lock-declarators is now
declared like this:
(defun c-font-lock-declarators (limit list types not-top &optional template-
class)  ...)
While in Emacs 25.3 and earlier it's declared like this:

(defun c-font-lock-declarators (limit list types)
  ...)

Basically the number of mandatory parameters has been bumped from 3 to
4, with another optional parameter added.
These kinds of changes makes it harder for third party modules to
maintain compatibility across Emacs-versions.
Wouldn't it be better to make *all *the new parameters optional and thus
maintain compatibility? Are there any good reasons not to do so?
--
Regards
Jostein Kjønigsen

jostein@kjonigsen.net 🍵 jostein@gmail.com
https://jostein.kjonigsen.net


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