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

[Alan Mackenzie]

Hello, Emacs.

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.

This is either a bug in the code, or a bug in the documentation.  I
rather tend to the view that this bold red highlighting should be done
when open-paren-in-column-0-is-defun-start is non-nil.  I think it did,
at one stage, but searching the emacs-devel archives doesn't reveal what
happened.

-- 
Alan Mackenzie (Nuremberg, Germany).