open parens in column zero and c-mode

open parens in column zero and c-mode

[martin rudalics]

With emacs -Q  open `syntax.c' and execute the following function:

(defun foo ()
   (interactive)
   (re-search-forward "string-to-syntax")
   (forward-line 6)
   (recenter 0))

My Emacs misfontifies some 20 lines with `font-lock-string-face' here.
The culprit is obviously the left paren before CODE in the doc-string of
`string-to-syntax'

(CODE . MATCHING-CHAR) that can be used as value of a `syntax-table'

and it would be easy to correct that.  What I want to ask, however, is
whether there's any good reason why

1. `open-paren-in-column-0-is-defun-start' is t in c-mode,

2. `syntax-begin-function' is not `c-beginning-of-defun' in c-mode, and

3. `beginning-of-defun-function' and `end-of-defun-function' are not
    respectively `c-beginning-of-defun' and `c-end-of-defun' in c-mode.

If any of these questions has to be answered with `yes' I'd suggest to
color left parens within comments at bol with `font-lock-warning-face'
as in Lisp mode to satisfy the following excerpt from the Emacs manual:

    "To help you catch violations of this convention, Font Lock mode
highlights confusing opening delimiters (those that ought to be quoted)
in bold red."