Re: lib/53682

[christos%zoulas.com@localhost (Christos Zoulas)]

The following reply was made to PR lib/53682; it has been noted by GNATS.

From: christos%zoulas.com@localhost (Christos Zoulas)
To: Nikhil Benesch <nikhil.benesch%gmail.com@localhost>, gnats-bugs%netbsd.org@localhost
Cc: jordan%cockroachlabs.com@localhost
Subject: Re: lib/53682
Date: Wed, 21 Nov 2018 12:22:52 -0500

 On Nov 21, 10:57am, nikhil.benesch%gmail.com@localhost (Nikhil Benesch) wrote:
 -- Subject: Re: lib/53682
 
 | Sorry, I'm struggling to stay in the loop on this PR since I'm not
 | subscribed to gnats-bugs. If you've previously rendered feedback on
 | this patch or the issue (i.e., before the mail that I've quoted above),
 | I'm afraid I can't see it.
 
 I probably replied to it in email before the PR was opened.
 
 | If you look more closely at the patch, you'll see that the remaining code
 | either issues a T_DO to move down multiple lines at once, or uses a for
 | loop to issue the requisite number of individual newlines. So it works
 | just fine if it needs to move more than one line.
 
 Ok, that is fine.
 
 | Is that what the code is intended to do? AFAICT you wrote and/or
 | imported this code into NetBSD, so you are the right person to ask. :)
 
 Yes, the code is from tcsh, we ended up using the <space><backspace> trick
 a long time ago to avoid breaking the lines.
 
 | The code I removed *unconditionally* issues
 | 
 |     <move-to-right-margin><space><backspace>
 
 I thought it does it only for terminals that have automatic margins. There
 is also the magic margins complication... This code is from 25 years ago,
 see the Fixes file for the magic margins changes.
 
 | regardless of whether the cursor is already at the right margin. If it
 | was only supposed to do that if the cursor was already at the right
 | margin, perhaps fixing that will also fix the problem described in this
 | PR.
 
 I think that it should do it only when we've reached the right margin.
 If that change fixes your issue then the problem is simple; if not, then
 we need to either figure out when to do the <space><backspace> trick
 and when not to.
 
 | The behavior you describe is the behavior I see both with and without
 | my patch. Are you speculating, are do you see incorrect behavior in
 | your terminal emulator with my patch? If the latter, I'd be happy to
 | investigate further if you tell me what terminal emulator you use.
 
 No, I have not tried your patch but I am guessing that it will break the
 single line in two. I will try to test, but I am really busy this week.
 The easiest way to test is to make the change on a NetBSD box and use
 the NetBSD /bin/sh with the editor on using an xterm (which has automatic
 margins and magic margins in the default setup).
 
 christos