bug#58804: Inconsistency between ruler-mode, fill-column and whitespace-mode

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 26 Oct 2022 20:22:37 +0000
> From:  Heime via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Having set both fill-column and whitespace-line-column to 72, I noticed the following.
> 
> ruler-mode has the left end marker at column 72

Do you mean "right end marker"?  I see no end marker at the left part
of the display here, only the ¶ marker at the right.

> but it should be at column 71 because column numbers start from 0.

I don't follow: ruler-mode counts columns starting from zero, as
everything in Emacs.  If you move point to a column other than the
leftmost one, you will see "0" at the left edge of the ruler display.
So having the marker at column 72 is exactly right.

Are you seeing this in "emacs -Q"?

> Here an improvement would be appreciated.  That is, having
> the ability to show a ruler variant that starts from value 1.  When one uses a block cursor,
> the ruler left marker would then mark exactly column 72.  The user will knew that if he inputs
> the next character he would have reached the line limit and the ruler left marker would coincide
> with that position.

It sounds like you want column numbers that start from 1, not zero?
That should be a session-wide mode (if we want such an enhancement),
since otherwise there could be confusion.  We currently support
one-based column only in the mode-line display under
column-number-mode.  Maybe you have turned that on, which is why you
think there's a mismatch in ruler-mode?