Cross staff dynamics

[Andrew Bernard]

I continually run into the problem where I have dynamics wth hairpins
across phrases which cross staves, causing lilypond to throw the
'cross fingers' error repeatedly in a cascade. Despite crossing
fingers (it is a well known fact I dislike this error expression) the
output places the dynamics poorly. If I left these errors in my score
I would have a hundred pages of the cross fingers output in the
compilation log, making it hard to see anything else.

Starting lilypond 2.19.44 [cross-staff-dynamics.ly]...
Processing `/home/andro/work/lilypond/fp/cross-staff-dynamics.ly'
Parsing...
Interpreting music...
Preprocessing graphical objects...
programming error: My pure_y_common is a VerticalAlignment, which
might contain several staves.
continuing, cross fingers
programming error: My pure_y_common is a VerticalAlignment, which
might contain several staves.
continuing, cross fingers
programming error: My pure_y_common is a VerticalAlignment, which
might contain several staves.
continuing, cross fingers
programming error: My pure_y_common is a VerticalAlignment, which
might contain several staves.
continuing, cross fingers
Finding the ideal number of pages...
Fitting music on 1 page...
Drawing systems...
Layout output to `/tmp/lilypond-2L7Ozf'...
Converting to `cross-staff-dynamics.pdf'...
Deleting `/tmp/lilypond-2L7Ozf'...
Success: compilation successfully completed


Is this a bug, or is it something fundamental I am doing incorrectly?

The workaround I have to use is to create a new voice for the bars in
question just for the dynamics. This is tedious and clutters the score
unnecessarily. For several reasons I do not want to create a dynamics
context in the score (this may be my mistake?).

MWE follows. [Probably not absolutely minimal, but it shows the
general context I have very often.]

Andrew

== snip

\version "2.19.44"

treble = {
  \clef treble
  \time 1/4

  \tupletUp
  \stemUp
  \tuplet 5/4 { f'''16_\f\> g'' a' fis'' ees' } |
  \tuplet 5/4 {
    c'' f' f'8
    \change Staff = bass
    \stemUp
    b16_\p } |
}

bass =  {
  \clef bass
  \time 1/4
  c4 c
}

\score {
  \new PianoStaff
  <<
    \new Staff = "treble" { \treble }
    \new Staff = "bass" { \bass }
  >>

  \layout { }
}



== snip