bug#3370: 23.0.94; `comment-region' indents comment chars inappropriately

[Drew Adams]

> Emacs put the comment-starters at column-0 because that code 
> was written a looooonnng time ago and keeping things simple
> was more important than now.

Emacs Lisp files still use ;; in column 0 in file headers, AFAICT. What column
would you prefer to indent them to?

That is exactly the use case here: commenting a line that will be in a file
header. There is nothing in the surrounding code that would indicate an
indentation level (other than 0 indent).

> Emacs-21's new commenting code was improved to be able to
> comment and uncomment at other columns than column-0, 

I have no problem with that.

> which made it more useful since most commenting styles use
> other indentation styles.

No idea what that means. Please define "commenting style" and "indentation
style" or otherwise explain what you're trying to say here.

> Emacs-21's default (as well as 22) was set to `plain' because Richard
> always puts such comments at column-0 (the `plain' setting 
> had actually to be added specifically for this).

Well I don't always put "such comments" (depending on what you mean by that) at
column 0. I put `;;' comments where Emacs has always put them: at the same level
of indentation that TAB puts code.

This is about commenting out a region, however, not about inserting a comment at
the current indentation level. Commenting out this line:

  `abcdef'

gives this, prior to Emacs 23:

;;   `abcdef'

Commenting out the line is different from inserting a comment at the same level:

  ;;
  `abcdef'

> If you don't like it, just (setq comment-style 'plain) and 
> live happily ever after.

Done (just let-bound in the pertinent code context). That's all I needed.

I would prefer, however, to _understand_, by getting some information about
`comment-style', `comment-styles', etc. Please document `comment-style' and the
rest of what might be missing. Please document this change in NEWS also.

Thx.