Re: master 87e7390: * lisp/progmodes/hideif.el: update for new C++ standards and extensions

[Luke Lee]

> hide-if still needs user to `hide-ifdef-define’ manually, could we use
> `lsp-mode’ to describe the macro to choose whether to hide or not?

Personally I never use `hide-ifdef-define', it's what it originally was
so I kept it.  I only use `hide-ifdefs' and EmacsSession to save/restore
`hide-ifdef-env' as I described long ago in EmacsWiki
https://www.emacswiki.org/emacs/HideIfDef (haven't got
time to update it yet).  Plus the newly described method in the
comment of the beginning of hideif.el:
[...]
;;   $ gcc -dM -E hello.c -o hello.hh
[...]
Then I open the hello.hh and `hide-ifdefs' it.  With EmacsSession I only
need to do that once.  Next time when I launch Emacs it will automatically
bring back my earlier defines.  As EmacsSession is not standard thus I
didn't mention that in the hideif.el comment.  I am sure there are now
some other packages able to save/restore the global `hide-ifdef-env'.

Hope this helps.

Best regards,
Luke Lee