Re: [Lilypond-auto] Issue 2990 in lilypond: \RemoveEmptyStaves in StaffGroup context crashes

[lilypond]

Comment #20 on issue 2990 by address@hidden: \RemoveEmptyStaves in  
StaffGroup context crashes
http://code.google.com/p/lilypond/issues/detail?id=2990

I've now moved the programming error out of production code.

Here are three other segfaults my patch fixes. I'd be interested to know if  
they exist in 2.16 and 2.14.

{
  \override NoteColumn #'before-line-breaking =
  #(lambda (grob)
    (ly:pointer-group-interface::add-grob grob 'elements grob))
  a4
}

{
  \override DynamicLineSpanner #'after-line-breaking =
  #(lambda (grob)
    (ly:pointer-group-interface::add-grob grob 'elements grob))
  a4\f\< a\!
}

{
  \override Staff.DotColumn #'before-line-breaking =
  #(lambda (grob)
    (ly:pointer-group-interface::add-grob grob 'elements grob))
  <a c>4.
}

If I'm understanding you correctly, you are advocating making checks in all  
functions that recurse through elements lists in order to prevent these  
segfaults.  I am advocating doing this only once - at the moment where the  
element is added to the grob array.