Re: Unconventional score and unwanted stray staff lines

[Thomas Morley]

Am Di., 21. Mai 2019 um 11:27 Uhr schrieb Urs Liska <address@hidden>:
>
>
>
> Am 21. Mai 2019 10:49:01 MESZ schrieb Thomas Morley <address@hidden>:
> >Am Di., 21. Mai 2019 um 02:32 Uhr schrieb Thomas Morley
> ><address@hidden>:
> >>
> >> Am So., 19. Mai 2019 um 20:32 Uhr schrieb Urs Liska
> ><address@hidden>:
> >>
> >> > The staves that continue to be printed appear to only happen when
> >the
> >> > last note in that staff is an actual printed note. If it's a rest
> >or a
> >> > space then the extra staves are not printed. Further
> >experimentation
> >> > and it looks like the extra staves are only printed if the final
> >note
> >> > is less than a quarter note (!).
> >> [..]
> >> > Maybe something to do with the time signature as well?
> >> >
> >> > This looks like a bug maybe?
> >> >
> >> > I could confirm that behaviour with the following MWE:
> >> >
> >> > \version "2.21.0"
> >> >
> >> > \score {
> >> >   <<
> >> >     \new Staff { c'1 c'1 }
> >> >     \new Staff { c'1 c'4 c'16 }
> >> >     \new Staff { c'1 c'8 }
> >> >     \new Staff { c'1 c'4 }
> >> >     \new Staff { c'1 c'4. }
> >> >   >>
> >> > }
> >> >
> >> > I too find this surprising. I suggest you ask on lilypond-user
> >whether this is a bug or intended behaviour. If it is intended (due to
> >some engraving convention for example) it might be made configurable.
> >>
> >> Looks like a bug to me.
> >>
> >> First bad commit:
> >>
> >> commit 9ff88d127acb371435a96e04cba7f0e3f525496d
> >> Author: Keith OHara <address@hidden>
> >> Date:   Sat Aug 6 12:05:59 2011 -0700
> >>
> >>     auto-beam-engraver: keep a Context_handle to starting Staff
> >>
> >> Which is in version 2.15.9
> >>
> >> cc-ing Keith
> >>
> >>
> >> Cheers,
> >>   Harm
> >
> >At least in the minimal one can workaround with inserting \noBeam:
> >
> >\score {
> >  <<
> >    \new Staff { c'1 c'1 }
> >    \new Staff { c'1 c'4 c'16 \noBeam }
> >    \new Staff { c'1 c'8 \noBeam }
> >    \new Staff { c'1 c'4 }
> >    \new Staff { c'1 c'4. }
> >  >>
> >}
> >
>
> Which might even be a pointer to the underlying trigger.
>
> Urs
>
> >Cheers,
> >  Harm

Finally I found it on the tracker:
https://sourceforge.net/p/testlilyissues/issues/1800/
Review at Rietveld:
https://codereview.appspot.com/4830064

And indeed

<<
  \new Voice {
    c8 c c
    \change Staff = "down"
    c
  }
  \context Staff = "down" s2
>>

segfaults without the patch


Cheers,
  Harm