Re: Gets vertical skylines from grob stencils (issue 5626052)

[k-ohara5a5a]

http://codereview.appspot.com/5626052/diff/114002/lily/skyline.cc
File lily/skyline.cc (right):

http://codereview.appspot.com/5626052/diff/114002/lily/skyline.cc#newcode111
lily/skyline.cc:111: if (start_height != end_height)
Does anyone know the reason for this change?

For some unusual input (issue 2836)
 { \override NoteHead #'stencil = ##f b2 b  }
both _heights can be NaNs, due to some other change in this patch.

This re-arrangement of logic looks like it /might/ have been intended to
set slope_=0 for NaNs on input, but in fact we get slope_=NaN and are
trapped at the assertion below.  (My reading of the standard says
NaN==NaN is false, NaN!=NaN is true, so gcc seems to comply.)

http://codereview.appspot.com/5626052/