bug#9148: Make `comment-normalize-vars' more syntax-aware

[Stefan Monnier]

> Unfortunately, even though there is a `comment-use-syntax' variable
> which is apparently supposed to indicate that the comment functions
> should rely on syntax information instead of `comment-prefix' and
> friends, one piece is missing -- the function `comment-normalize-vars',
> called at invocation of functions like {comment,uncomment}-region, still
> requires `comment-start' to be set explicitly even though the syntax
> information is sufficient and `comment-use-syntax' set.

I'm not sure I understand the problem.  Can you give a more concrete
example where you get undesirable behavior?
Setting comment-start is usually needed to tell Emacs *which* of the
major mode's comment syntaxes to use (so it's only theoretically
unneeded if the syntax-table only include a single comment syntax).


        Stefan