bug#21871: Emacs Lisp Mode (at least): spurious parens in column 0 don't get bold red highlighting.

[Noam Postavsky]

Alan Mackenzie <acm@muc.de> writes:

> In the Emacs manual page "Left Margin Paren", it says that:
>
>    To help you catch violations of this convention, Font Lock mode
>    highlights confusing opening delimiters (those that ought to be quoted)
>    in bold red.
>
> , where "this convention" is the convention of not putting opening parens
> in column 0 when they aren't at the beginning of defuns.
>
> In Emacs Lisp Mode, this highlighting isn't done.  It isn't in CC Mode,
> either.

The recent thread in emacs-devel[1] reminded me I wrote a (still
half-baked) patch for this.

[1]: https://lists.gnu.org/r/emacs-devel/2020-04/msg00402.html

0001-WIP-Restore-highlighting-of-open-parens-in-column-0-.patch
Description: patch