[bug #63873] \~ can overwrite previous text.

[Alejandro Colomar]

URL:
  <https://savannah.gnu.org/bugs/?63873>

                 Summary: \~ can overwrite previous text.
                   Group: GNU roff
               Submitter: alx
               Submitted: Mon 06 Mar 2023 02:26:20 PM UTC
                Category: None
                Severity: 3 - Normal
              Item Group: Rendering/Cosmetics
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None


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Follow-up Comments:


-------------------------------------------------------
Date: Mon 06 Mar 2023 02:26:20 PM UTC By: Alejandro Colomar <alx>
Reproducible in both 1.22.4 and 1.23.0-HEAD.

Reproducer:

$ cat interval.man 
.TH interval notation to-day experiments
.SH Description
What happens if we use interval notation,
with some formatting?
.RB [ 0 ,\~ USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX ]
And make the terminal very short?
.IP
To make things worse, let's add indentation:
.RB [ 1 ,\~ USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX ].
.RS 8
.PP
Let's see with a moved left margin:
.RB [ 2 ,\~ USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX ].
.IP
Why not both things?
.RB [ 3 ,\~ USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX ].
.IP
It seems to be independent of the margin of indentation,
but maybe with a different space things change:
.RB [ 4 ",\ " USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX ].
.IP
Indeed, this last paragraph was better.
It seems top be a bug with \e\[ti].
.RE


See how it renders (admittedly, there are warnings):


$ groff --version | head -n1
GNU groff version 1.23.0.rc3.43-0221b
$ groff -man -Tutf8 -rLL=60n interval.man 
troff:interval.man:5: warning [p 1, 0.7i]: cannot adjust line
troff:interval.man:5: warning [p 1, 0.8i]: cannot break line
troff:interval.man:9: warning [p 1, 1.5i]: cannot break line
troff:interval.man:13: warning [p 1, 2.0i]: cannot break line
troff:interval.man:16: warning [p 1, 2.5i]: cannot break line
troff:interval.man:20: warning [p 1, 3.3i]: cannot break line
interval(notation)                        interval(notation)

Description
       What  happens  if we use interval notation, with some
       formatting?
      USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX]
       And make the terminal very short?

              To  make  things worse, let’s add indentation:
     USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX].

               Let’s   see   with   a   moved  left  margin:
     USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX].

                      Why       not       both       things?
     USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX].

                      It seems to be independent of the mar‐
                      gin  of  indentation, but maybe with a
                      different   space    things    change:
                      [4,
USHRTrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrtrt_MAX].

                      Indeed,  this  last paragraph was bet‐
                      ter.  It seems top be a bug with \~.

experiments                to‐day         interval(notation)


On 3/6/23 14:47, G. Branden Robinson wrote:
> Just from eyeballing the behavior, it looks like there is no lower bound
> on the size of a "stretchable" ("paddable") space, and there should be.
> Or equivalently, the "stretch" should not be permitted to take negative
> values.







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