Issue 1618 in lilypond: unpredictable placement of rests

[lilypond]

Status: Accepted
Owner: ----
Labels: Type-Defect Priority-Critical

New issue 1618 by percival.music.ca: unpredictable placement of rests
http://code.google.com/p/lilypond/issues/detail?id=1618

This is split from issue 1609 (that issue was specifically about the  
problem we saw in partcombine-midi.ly)


As the examples below illustrate, placement of such rests still changes  
unpredictably.  The score in example 2 produces different output with the  
two command lines
 lilypond test.ly
 lilypond test.ly test.ly
while version 2.12.3 produces the same output in either case.  Both  
versions produce a warning "too many colliding rests".  See also issue 1547  
and issue 384.

The variation in position of the rests appeared somewhere between 2.13.48  
and .54


The completion- engravers are not essential, it is simply the fact that  
LilyPond does not have a rule to place simultaneous rests with a note of  
different durations (see issue 1547).  Smaller example, which produces  
different output depending on whether the file is alone on the command line  
or second in a list of .ly files:

\version "2.12.3"
\new Staff <<
  \new Voice {
    \voiceOne
    r1 r1
  }
  \new Voice {
    \voiceThree
    c'2 e' g' b'
  }
  \new Voice {
    \voiceTwo
    r1 r1
  }