bug#5117: 23.1.50; Weird display when wrap-prefix contains tabs

[Andrew Hyatt]

Chong Yidong <cyd@stupidchicken.com> writes:

>> > The "+ it->continuation_lines_width" was added for a reason.
>>
>> I tracked back through the history of the code, and that part has been
>> there since the code was introduced as far as I can tell.
>>
>> > IIRC, it is so that continued lines containing tabs are displayed 
>> > correctly.
>>
>> Can you define "correctly"?  When I remove the addition, it displays
>> 'correctly' from what I expect: a tab always indents the text to the
>> next visual column that's a multiple of 8.
>
> Sorry for the delay in replying.
>
> Suppose that (i) next tab stop is 3 characters off the right edge of the
> text area, and (ii) you have text going all the way to the right edge.
> Now insert a tab character.  With the current code, Emacs displays the
> tab up to the 3rd character of the continuation line.  This is
> "correct", in the sense that the continuation line is a "continuation"
> of the previous line with the tab stops picking up where they left off.
>
> With the patch you propose, Emacs would instead display up to the 8th
> character of the continuation line.

Since it seems that this is (according to Chong) not a bug, but the way
things should work, I' m going to close this bug.  Feel free to
disagree; we can always re-open it.